hrtimers: Update formatting of documentation

Documentation of functions lacks the annotations which are used by
kernel-doc and *.rst to make appearance in rendered documents more
user-friendly.

Use those annotations to improve user-friendliness. While at it prevent
duplication of comments and use a reference instead.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240123164702.55612-3-anna-maria@linutronix.de

hrtimers: Move hrtimer base related definitions into hrtimer_defs.h

hrtimer base related struct definitions are part of hrtimers.h as it is
required there. With this, also the struct documentation which is for core
code internal use, is exposed into the general api.

To prevent this, move all core internal definitions and the related
includes into hrtimer_defs.h.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240123164702.55612-2-anna-maria@linutronix.de

hrtimer: Report offline hrtimer enqueue

The hrtimers migration on CPU-down hotplug process has been moved
earlier, before the CPU actually goes to die. This leaves a small window
of opportunity to queue an hrtimer in a blind spot, leaving it ignored.

For example a practical case has been reported with RCU waking up a
SCHED_FIFO task right before the CPUHP_AP_IDLE_DEAD stage, queuing that
way a sched/rt timer to the local offline CPU.

Make sure such situations never go unnoticed and warn when that happens.

Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier")
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240129235646.3171983-4-boqun.feng@gmail.com

hrtimers: Split out hrtimer_types.h

We need to reduce the scope of what's included in sched.h: task_struct
includes a hrtimer, so split out the core types into their own header.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Thomas Gleixner <tglx@linutronix.de>

timekeeping: Kill percpu.h dependency

Slimming down recursive header includes.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Thomas Gleixner <tglx@linutronix.de>

hrtimers: Push pending hrtimers away from outgoing CPU earlier

2b8272ff4a70 ("cpu/hotplug: Prevent self deadlock on CPU hot-unplug")
solved the straight forward CPU hotplug deadlock vs. the scheduler
bandwidth timer. Yu discovered a more involved variant where a task which
has a bandwidth timer started on the outgoing CPU holds a lock and then
gets throttled. If the lock required by one of the CPU hotplug callbacks
the hotplug operation deadlocks because the unthrottling timer event is not
handled on the dying CPU and can only be recovered once the control CPU
reaches the hotplug state which pulls the pending hrtimers from the dead
CPU.

Solve this by pushing the hrtimers away from the dying CPU in the dying
callbacks. Nothing can queue a hrtimer on the dying CPU at that point because
all other CPUs spin in stop_machine() with interrupts disabled and once the
operation is finished the CPU is marked offline.

Reported-by: Yu Liao <liaoyu15@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Liu Tie <liutie4@huawei.com>
Link: https://lore.kernel.org/r/87a5rphara.ffs@tglx

timekeeping: Distangle resume and clock-was-set events

Resuming timekeeping is a clock-was-set event and uses the clock-was-set
notification mechanism. This is in the way of making the clock-was-set
update for hrtimers selective so unnecessary IPIs are avoided when a CPU
base does not have timers queued which are affected by the clock setting.

Distangle it by invoking hrtimer_resume() on each unfreezing CPU and invoke
the new timerfd_resume() function from timekeeping_resume() which is the
only place where this is needed.

Rename hrtimer_resume() to hrtimer_resume_local() to reflect the change.

With this the clock_was_set*() functions are not longer required to IPI all
CPUs unconditionally and can get some smarts to avoid them.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210713135158.488853478@linutronix.de

timerfd: Provide timerfd_resume()

Resuming timekeeping is a clock-was-set event and uses the clock-was-set
notification mechanism. This is in the way of making the clock-was-set
update for hrtimers selective so unnecessary IPIs are avoided when a CPU
base does not have timers queued which are affected by the clock setting.

Provide a seperate timerfd_resume() interface so the resume logic and the
clock-was-set mechanism can be distangled in the core code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210713135158.395287410@linutronix.de

hrtimer: Ensure timerfd notification for HIGHRES=n

If high resolution timers are disabled the timerfd notification about a
clock was set event is not happening for all cases which use
clock_was_set_delayed() because that's a NOP for HIGHRES=n, which is wrong.

Make clock_was_set_delayed() unconditially available to fix that.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210713135158.196661266@linutronix.de

hrtimer: Fix kernel-doc markups

The hrtimer_get_remaining() markup is documenting, instead,
__hrtimer_get_remaining(), as it is placed at the C file.

In order to properly document it, a kernel-doc markup is needed together
with the function prototype. So, add a new one, while preserving the
existing one, just fixing the function name.

The hrtimer_is_queued prototype has a typo: it is using
'=' instead of '-' to split: identifier - description
as required by kernel-doc markup.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/9dc87808c2fd07b7e050bafcd033c5ef05808fea.1605521731.git.mchehab+huawei@kernel.org

locking/seqlock, headers: Untangle the spaghetti monster

By using lockdep_assert_*() from seqlock.h, the spaghetti monster
attacked.

Attack back by reducing seqlock.h dependencies from two key high level headers:

- <linux/seqlock.h>: -Remove <linux/ww_mutex.h>
- <linux/time.h>: -Remove <linux/seqlock.h>
- <linux/sched.h>: +Add <linux/seqlock.h>

The price was to add it to sched.h ...

Core header fallout, we add direct header dependencies instead of gaining them
parasitically from higher level headers:

- <linux/dynamic_queue_limits.h>: +Add <asm/bug.h>
- <linux/hrtimer.h>: +Add <linux/seqlock.h>
- <linux/ktime.h>: +Add <asm/bug.h>
- <linux/lockdep.h>: +Add <linux/smp.h>
- <linux/sched.h>: +Add <linux/seqlock.h>
- <linux/videodev2.h>: +Add <linux/kernel.h>

Arch headers fallout:

- PARISC: <asm/timex.h>: +Add <asm/special_insns.h>
- SH: <asm/io.h>: +Add <asm/page.h>
- SPARC: <asm/timer_64.h>: +Add <uapi/asm/asi.h>
- SPARC: <asm/vvar.h>: +Add <asm/processor.h>, <asm/barrier.h>
-Remove <linux/seqlock.h>
- X86: <asm/fixmap.h>: +Add <asm/pgtable_types.h>
-Remove <asm/acpi.h>

There's also a bunch of parasitic header dependency fallout in .c files, not listed
separately.

[ mingo: Extended the changelog, split up & fixed the original patch. ]

Co-developed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200804133438.GK2674@hirez.programming.kicks-ass.net

hrtimer: Use sequence counter with associated raw spinlock

A sequence counter write side critical section must be protected by some
form of locking to serialize writers. A plain seqcount_t does not
contain the information of which lock must be held when entering a write
side critical section.

Use the new seqcount_raw_spinlock_t data type, which allows to associate
a raw spinlock with the sequence counter. This enables lockdep to verify
that the raw spinlock used for writer serialization is held when the
write side critical section is entered.

If lockdep is disabled this lock association is compiled out and has
neither storage size nor runtime overhead.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200720155530.1173732-25-a.darwish@linutronix.de

hrtimers: Prepare hrtimer_nanosleep() for time namespaces

clock_nanosleep() accepts absolute values of expiration time when
TIMER_ABSTIME flag is set. This absolute value is inside the task's
time namespace, and has to be converted to the host's time.

There is timens_ktime_to_host() helper for converting time, but
it accepts ktime argument.

As a preparation, make hrtimer_nanosleep() accept a clock value in ktime
instead of timespec64.

Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-17-dima@arista.com

hrtimer: Annotate lockless access to timer->state

syzbot reported various data-race caused by hrtimer_is_queued() reading
timer->state. A READ_ONCE() is required there to silence the warning.

Also add the corresponding WRITE_ONCE() when timer->state is set.

In remove_hrtimer() the hrtimer_is_queued() helper is open coded to avoid
loading timer->state twice.

KCSAN reported these cases:

BUG: KCSAN: data-race in __remove_hrtimer / tcp_pacing_check

write to 0xffff8880b2a7d388 of 1 bytes by interrupt on cpu 0:
__remove_hrtimer+0x52/0x130 kernel/time/hrtimer.c:991
__run_hrtimer kernel/time/hrtimer.c:1496 [inline]
__hrtimer_run_queues+0x250/0x600 kernel/time/hrtimer.c:1576
hrtimer_run_softirq+0x10e/0x150 kernel/time/hrtimer.c:1593
__do_softirq+0x115/0x33f kernel/softirq.c:292
run_ksoftirqd+0x46/0x60 kernel/softirq.c:603
smpboot_thread_fn+0x37d/0x4a0 kernel/smpboot.c:165
kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff8880b2a7d388 of 1 bytes by task 24652 on cpu 1:
tcp_pacing_check net/ipv4/tcp_output.c:2235 [inline]
tcp_pacing_check+0xba/0x130 net/ipv4/tcp_output.c:2225
tcp_xmit_retransmit_queue+0x32c/0x5a0 net/ipv4/tcp_output.c:3044
tcp_xmit_recovery+0x7c/0x120 net/ipv4/tcp_input.c:3558
tcp_ack+0x17b6/0x3170 net/ipv4/tcp_input.c:3717
tcp_rcv_established+0x37e/0xf50 net/ipv4/tcp_input.c:5696
tcp_v4_do_rcv+0x381/0x4e0 net/ipv4/tcp_ipv4.c:1561
sk_backlog_rcv include/net/sock.h:945 [inline]
__release_sock+0x135/0x1e0 net/core/sock.c:2435
release_sock+0x61/0x160 net/core/sock.c:2951
sk_stream_wait_memory+0x3d7/0x7c0 net/core/stream.c:145
tcp_sendmsg_locked+0xb47/0x1f30 net/ipv4/tcp.c:1393
tcp_sendmsg+0x39/0x60 net/ipv4/tcp.c:1434
inet_sendmsg+0x6d/0x90 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:637 [inline]
sock_sendmsg+0x9f/0xc0 net/socket.c:657

BUG: KCSAN: data-race in __remove_hrtimer / __tcp_ack_snd_check

write to 0xffff8880a3a65588 of 1 bytes by interrupt on cpu 0:
__remove_hrtimer+0x52/0x130 kernel/time/hrtimer.c:991
__run_hrtimer kernel/time/hrtimer.c:1496 [inline]
__hrtimer_run_queues+0x250/0x600 kernel/time/hrtimer.c:1576
hrtimer_run_softirq+0x10e/0x150 kernel/time/hrtimer.c:1593
__do_softirq+0x115/0x33f kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0xbb/0xe0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830

read to 0xffff8880a3a65588 of 1 bytes by task 22891 on cpu 1:
__tcp_ack_snd_check+0x415/0x4f0 net/ipv4/tcp_input.c:5265
tcp_ack_snd_check net/ipv4/tcp_input.c:5287 [inline]
tcp_rcv_established+0x750/0xf50 net/ipv4/tcp_input.c:5708
tcp_v4_do_rcv+0x381/0x4e0 net/ipv4/tcp_ipv4.c:1561
sk_backlog_rcv include/net/sock.h:945 [inline]
__release_sock+0x135/0x1e0 net/core/sock.c:2435
release_sock+0x61/0x160 net/core/sock.c:2951
sk_stream_wait_memory+0x3d7/0x7c0 net/core/stream.c:145
tcp_sendmsg_locked+0xb47/0x1f30 net/ipv4/tcp.c:1393
tcp_sendmsg+0x39/0x60 net/ipv4/tcp.c:1434
inet_sendmsg+0x6d/0x90 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:637 [inline]
sock_sendmsg+0x9f/0xc0 net/socket.c:657
__sys_sendto+0x21f/0x320 net/socket.c:1952
__do_sys_sendto net/socket.c:1964 [inline]
__se_sys_sendto net/socket.c:1960 [inline]
__x64_sys_sendto+0x89/0xb0 net/socket.c:1960
do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 24652 Comm: syz-executor.3 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

[ tglx: Added comments ]

Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191106174804.74723-1-edumazet@google.com

hrtimer: Add kernel doc annotation for HRTIMER_MODE_HARD

Add kernel doc annotation for HRTIMER_MODE_HARD.

Fixes: ae6683d815895 ("hrtimer: Introduce HARD expiry mode")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190823113845.12125-2-bigeasy@linutronix.de

hrtimer: Prepare support for PREEMPT_RT

When PREEMPT_RT is enabled, the soft interrupt thread can be preempted. If
the soft interrupt thread is preempted in the middle of a timer callback,
then calling hrtimer_cancel() can lead to two issues:

- If the caller is on a remote CPU then it has to spin wait for the timer
handler to complete. This can result in unbound priority inversion.

- If the caller originates from the task which preempted the timer
handler on the same CPU, then spin waiting for the timer handler to
complete is never going to end.

To avoid these issues, add a new lock to the timer base which is held
around the execution of the timer callbacks. If hrtimer_cancel() detects
that the timer callback is currently running, it blocks on the expiry
lock. When the callback is finished, the expiry lock is dropped by the
softirq thread which wakes up the waiter and the system makes progress.

This addresses both the priority inversion and the life lock issues.

The same issue can happen in virtual machines when the vCPU which runs a
timer callback is scheduled out. If a second vCPU of the same guest calls
hrtimer_cancel() it will spin wait for the other vCPU to be scheduled back
in. The expiry lock mechanism would avoid that. It'd be trivial to enable
this when paravirt spinlocks are enabled in a guest, but it's not clear
whether this is an actual problem in the wild, so for now it's an RT only
mechanism.

[ tglx: Refactored it for mainline ]

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726185753.737767218@linutronix.de

hrtimer: Make enqueue mode check work on RT

hrtimer_start_range_ns() has a WARN_ONCE() which verifies that a timer
which is marker for softirq expiry is not queued in the hard interrupt base
and vice versa.

When PREEMPT_RT is enabled, timers which are not explicitely marked to
expire in hard interrupt context are deferrred to the soft interrupt. So
the regular check would trigger.

Change the check, so when PREEMPT_RT is enabled, it is verified that the
timers marked for hard interrupt expiry are not tried to be queued for soft
interrupt expiry or any of the unmarked and softirq marked is tried to be
expired in hard interrupt context.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Introduce HARD expiry mode

On PREEMPT_RT not all hrtimers can be expired in hard interrupt context
even if that is perfectly fine on a PREEMPT_RT=n kernel, e.g. because they
take regular spinlocks. Also for latency reasons PREEMPT_RT tries to defer
most hrtimers' expiry into soft interrupt context.

But there are hrtimers which must be expired in hard interrupt context even
when PREEMPT_RT is enabled:

- hrtimers which must expiry in hard interrupt context, e.g. scheduler,
perf, watchdog related hrtimers

- latency critical hrtimers, e.g. nanosleep, ..., kvm lapic timer

Add a new mode flag HRTIMER_MODE_HARD which allows to mark these timers so
PREEMPT_RT will not move them into softirq expiry mode.

[ tglx: Split out of a larger combo patch. Added changelog ]

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726185752.981398465@linutronix.de

hrtimer: Provide hrtimer_sleeper_start_expires()

hrtimer_sleepers will gain a scheduling class dependent treatment on
PREEMPT_RT. Create a wrapper around hrtimer_start_expires() to make that
possible.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Consolidate hrtimer_init() + hrtimer_init_sleeper() calls

hrtimer_init_sleeper() calls require prior initialisation of the hrtimer
object which is embedded into the hrtimer_sleeper.

Combine the initialization and spare a function call. Fixup all call sites.

This is also a preparatory change for PREEMPT_RT to do hrtimer sleeper
specific initializations of the embedded hrtimer without modifying any of
the call sites.

No functional change.

[ anna-maria: Minor cleanups ]
[ tglx: Adopted to the removal of the task argument of
hrtimer_init_sleeper() and trivial polishing.
Folded a fix from Stephen Rothwell for the vsoc code ]

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726185752.887468908@linutronix.de

hrtimer: Remove task argument from hrtimer_init_sleeper()

All callers hand in 'current' and that's the only task pointer which
actually makes sense. Remove the task argument and set current in the
function.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726185752.791885290@linutronix.de

hrtimer: Split out hrtimer defines into separate header

To avoid include dependency hell split out the hrtimer defines which are
required in the upcoming VDSO library into a separate header file.

[ tglx: Split out from the VDSO library patch and included ktime.h as
the new header depends on it. ]

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Shijith Thotton <sthotton@marvell.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Huw Davies <huw@codeweavers.com>
Link: https://lkml.kernel.org/r/20190621095252.32307-3-vincenzo.frascino@arm.com

hrtimers/tick/clockevents: Remove sloppy license references

"For licencing details see kernel-base/COPYING" and similar license
references have no value over the SPDX identifier. Remove them.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Corey Minyard <cminyard@mvista.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: David Riley <davidriley@chromium.org>
Cc: Colin Cross <ccross@android.com>
Cc: Mark Brown <broonie@kernel.org>
Link: https://lkml.kernel.org/r/20181031182252.963632760@linutronix.de

time: Add SPDX license identifiers

Update the time(r) core files files with the correct SPDX license
identifier based on the license text in the file itself. The SPDX
identifier is a legally binding shorthand, which can be used instead of the
full boiler plate text.

This work is based on a script and data from Philippe Ombredanne, Kate
Stewart and myself. The data has been created with two independent license
scanners and manual inspection.

The following files do not contain any direct license information and have
been omitted from the big initial SPDX changes:

timeconst.bc: The .bc files were not touched
time.c, timer.c, timekeeping.c: Licence was deduced from EXPORT_SYMBOL_GPL

As those files do not contain direct license references they fall under the
project license, i.e. GPL V2 only.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Corey Minyard <cminyard@mvista.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: David Riley <davidriley@chromium.org>
Cc: Colin Cross <ccross@android.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: https://lkml.kernel.org/r/20181031182252.879109557@linutronix.de

time: Remove useless filenames in top level comments

Remove the pointless filenames in the top level comments. They have no
value at all and just occupy space. While at it tidy up some of the
comments and remove a stale one.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Corey Minyard <cminyard@mvista.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: David Riley <davidriley@chromium.org>
Cc: Colin Cross <ccross@android.com>
Cc: Mark Brown <broonie@kernel.org>
Link: https://lkml.kernel.org/r/20181031182252.794898238@linutronix.de

Revert: Unify CLOCK_MONOTONIC and CLOCK_BOOTTIME

Revert commits

92af4dcb4e1c ("tracing: Unify the "boot" and "mono" tracing clocks")
127bfa5f4342 ("hrtimer: Unify MONOTONIC and BOOTTIME clock behavior")
7250a4047aa6 ("posix-timers: Unify MONOTONIC and BOOTTIME clock behavior")
d6c7270e913d ("timekeeping: Remove boot time specific code")
f2d6fdbfd238 ("Input: Evdev - unify MONOTONIC and BOOTTIME clock behavior")
d6ed449afdb3 ("timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock")
72199320d49d ("timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock")

As stated in the pull request for the unification of CLOCK_MONOTONIC and
CLOCK_BOOTTIME, it was clear that we might have to revert the change.

As reported by several folks systemd and other applications rely on the
documented behaviour of CLOCK_MONOTONIC on Linux and break with the above
changes. After resume daemons time out and other timeout related issues are
observed. Rafael compiled this list:

* systemd kills daemons on resume, after >WatchdogSec seconds
of suspending (Genki Sky). [Verified that that's because systemd uses
CLOCK_MONOTONIC and expects it to not include the suspend time.]

* systemd-journald misbehaves after resume:
systemd-journald[7266]: File /var/log/journal/016627c3c4784cd4812d4b7e96a34226/system.journal
corrupted or uncleanly shut down, renaming and replacing.
(Mike Galbraith).

* NetworkManager reports "networking disabled" and networking is broken
after resume 50% of the time (Pavel). [May be because of systemd.]

* MATE desktop dims the display and starts the screensaver right after
system resume (Pavel).

* Full system hang during resume (me). [May be due to systemd or NM or both.]

That happens on debian and open suse systems.

It's sad, that these problems were neither catched in -next nor by those
folks who expressed interest in this change.

Reported-by: Rafael J. Wysocki <rjw@rjwysocki.net>
Reported-by: Genki Sky <sky@genki.is>,
Reported-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Easton <kevin@guarana.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>

time: hrtimer: Introduce hrtimer_next_event_without()

The next set of changes will need to compute the time to the next
hrtimer event over all hrtimers except for the scheduler tick one.

To that end introduce a new helper function,
hrtimer_next_event_without(), for computing the time until the next
hrtimer event over all timers except for one and modify the underlying
code in __hrtimer_next_event_base() to prepare it for being called by
that new function.

No intentional changes in functionality.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>

hrtimer: Unify MONOTONIC and BOOTTIME clock behavior

Now that th MONOTONIC and BOOTTIME clocks are indentical remove all the special
casing.

The user space visible interfaces still support both clocks, but their behavior
is identical.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Easton <kevin@guarana.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20180301165150.410218515@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Implement support for softirq based hrtimers

hrtimer callbacks are always invoked in hard interrupt context. Several
users in tree require soft interrupt context for their callbacks and
achieve this by combining a hrtimer with a tasklet. The hrtimer schedules
the tasklet in hard interrupt context and the tasklet callback gets invoked
in softirq context later.

That's suboptimal and aside of that the real-time patch moves most of the
hrtimers into softirq context. So adding native support for hrtimers
expiring in softirq context is a valuable extension for both mainline and
the RT patch set.

Each valid hrtimer clock id has two associated hrtimer clock bases: one for
timers expiring in hardirq context and one for timers expiring in softirq
context.

Implement the functionality to associate a hrtimer with the hard or softirq
related clock bases and update the relevant functions to take them into
account when the next expiry time needs to be evaluated.

Add a check into the hard interrupt context handler functions to check
whether the first expiring softirq based timer has expired. If it's expired
the softirq is raised and the accounting of softirq based timers to
evaluate the next expiry time for programming the timer hardware is skipped
until the softirq processing has finished. At the end of the softirq
processing the regular processing is resumed.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-29-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Add clock bases and hrtimer mode for softirq context

Currently hrtimer callback functions are always executed in hard interrupt
context. Users of hrtimers, which need their timer function to be executed
in soft interrupt context, make use of tasklets to get the proper context.

Add additional hrtimer clock bases for timers which must expire in softirq
context, so the detour via the tasklet can be avoided. This is also
required for RT, where the majority of hrtimer is moved into softirq
hrtimer context.

The selection of the expiry mode happens via a mode bit. Introduce
HRTIMER_MODE_SOFT and the matching combinations with the ABS/REL/PINNED
bits and update the decoding of hrtimer_mode in tracepoints.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-27-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Make hrtimer_reprogramm() unconditional

hrtimer_reprogram() needs to be available unconditionally for softirq based
hrtimers. Move the function and all required struct members out of the
CONFIG_HIGH_RES_TIMERS #ifdef.

There is no functional change because hrtimer_reprogram() is only invoked
when hrtimer_cpu_base.hres_active is true. Making it unconditional
increases the text size for the CONFIG_HIGH_RES_TIMERS=n case, but avoids
replication of that code for the upcoming softirq based hrtimers support.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-18-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Make hrtimer_cpu_base.next_timer handling unconditional

hrtimer_cpu_base.next_timer stores the pointer to the next expiring timer
in a CPU base.

This pointer cannot be dereferenced and is solely used to check whether a
hrtimer which is removed is the hrtimer which is the first to expire in the
CPU base. If this is the case, then the timer hardware needs to be
reprogrammed to avoid an extra interrupt for nothing.

Again, this is conditional functionality, but there is no compelling reason
to make this conditional. As a preparation, hrtimer_cpu_base.next_timer
needs to be available unconditonally.

Aside of that the upcoming support for softirq based hrtimers requires access
to this pointer unconditionally as well, so our motivation is not entirely
simplicity based.

Make the update of hrtimer_cpu_base.next_timer unconditional and remove the
#ifdef cruft. The impact on CONFIG_HIGH_RES_TIMERS=n && CONFIG_NOHZ=n is
marginal as it's just a store on an already dirtied cacheline.

No functional change.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-17-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Make the remote enqueue check unconditional

hrtimer_cpu_base.expires_next is used to cache the next event armed in the
timer hardware. The value is used to check whether an hrtimer can be
enqueued remotely. If the new hrtimer is expiring before expires_next, then
remote enqueue is not possible as the remote hrtimer hardware cannot be
accessed for reprogramming to an earlier expiry time.

The remote enqueue check is currently conditional on
CONFIG_HIGH_RES_TIMERS=y and hrtimer_cpu_base.hres_active. There is no
compelling reason to make this conditional.

Move hrtimer_cpu_base.expires_next out of the CONFIG_HIGH_RES_TIMERS=y
guarded area and remove the conditionals in hrtimer_check_target().

The check is currently a NOOP for the CONFIG_HIGH_RES_TIMERS=n and the
!hrtimer_cpu_base.hres_active case because in these cases nothing updates
hrtimer_cpu_base.expires_next yet. This will be changed with later patches
which further reduce the #ifdef zoo in this code.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-16-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Make the hrtimer_cpu_base::hres_active field unconditional, to simplify the code

The hrtimer_cpu_base::hres_active_member field depends on CONFIG_HIGH_RES_TIMERS=y
currently, and all related functions to this member are conditional as well.

To simplify the code make it unconditional and set it to zero during initialization.

(This will also help with the upcoming softirq based hrtimers code.)

The conditional code sections can be avoided by adding IS_ENABLED(HIGHRES)
conditionals into common functions, which ensures dead code elimination.

There is no functional change.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-14-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Make room in 'struct hrtimer_cpu_base'

The upcoming softirq based hrtimers support requires an additional field in
the hrtimer_cpu_base struct, which would grow the struct size beyond a
cache line.

The hrtimer_cpu_base::nr_retries and ::nr_hangs members are solely
used for diagnostic output and have no requirement to be 'unsigned int'.

Make them 'unsigned short' to create room for the new struct member.

No functional change.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-13-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Store running timer in hrtimer_clock_base

The pointer to the currently running timer is stored in hrtimer_cpu_base
before the base lock is dropped and the callback is invoked.

This results in two levels of indirections and the upcoming support for
softirq based hrtimer requires splitting the "running" storage into soft
and hard IRQ context expiry.

Storing both in the cpu base would require conditionals in all code paths
accessing that information.

It's possible to have a per clock base sequence count and running pointer
without changing the semantics of the related mechanisms because the timer
base pointer cannot be changed while a timer is running the callback.

Unfortunately this makes cpu_clock base larger than 32 bytes on 32-bit
kernels. Instead of having huge gaps due to alignment, remove the alignment
and let the compiler pack CPU base for 32-bit kernels. The resulting cache access
patterns are fortunately not really different from the current
behaviour. On 64-bit kernels the 64-byte alignment stays and the behaviour is
unchanged. This was determined by analyzing the resulting layout and
looking at the number of cache lines involved for the frequently used
clocks.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-12-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Clean up 'enum hrtimer_mode'

It's not obvious that the HRTIMER_MODE variants are bit combinations,
because all modes are hard coded constants currently.

Change it so the bit meanings are clear; and use the symbols for creating
modes which combine bits.

While at it get rid of the ugly tail comments as well.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-8-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Fix hrtimer_start[_range_ns]() function descriptions

The hrtimer_start[_range_ns]() functions start a timer reliably on this CPU only
when HRTIMER_MODE_PINNED is set.

Furthermore the HRTIMER_MODE_PINNED mode is not considered when a hrtimer is initialized.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-6-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Clean up the 'int clock' parameter of schedule_hrtimeout_range_clock()

schedule_hrtimeout_range_clock() uses an 'int clock' parameter for the
clock ID, instead of the customary predefined "clockid_t" type.

In hrtimer coding style the canonical variable name for the clock ID is
'clock_id', therefore change the name of the parameter here as well
to make it all consistent.

While at it, clean up the description for the 'clock_id' and 'mode'
function parameters. The clock modes and the clock IDs are not
restricted as the comment suggests.

Fix the mode description as well for the callers of schedule_hrtimeout_range_clock().

No functional changes intended.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-5-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Fix kerneldoc syntax for 'struct hrtimer_cpu_base'

The '/**' sequence marks the start of a structure description. Add the
missing second asterisk. While at it adapt the ordering of the struct
members to the struct definition and document the purpose of
expires_next more precisely.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-4-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

hrtimer: Optimize the hrtimer code by using static keys for migration_enable/nohz_active

The hrtimer_cpu_base::migration_enable and ::nohz_active fields
were originally introduced to avoid accessing global variables
for these decisions.

Still that results in a (cache hot) load and conditional branch,
which can be avoided by using static keys.

Implement it with static keys and optimize for the most critical
case of high performance networking which tends to disable the
timer migration functionality.

No change in functionality.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1801142327490.2371@nanos
Link: https://lkml.kernel.org/r/20171221104205.7269-2-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

nanosleep: Use get_timespec64() and put_timespec64()

Usage of these apis and their compat versions makes
the syscalls: clock_nanosleep and nanosleep and
their compat implementations simpler.

This is a preparatory patch to isolate data conversions to
struct timespec64 at userspace boundaries. This helps contain
the changes needed to transition to new y2038 safe types.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

posix-timers: Make nanosleep timespec argument const

No nanosleep implementation modifies the rqtp argument. Mark is const.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>

posix-timers: Kill ->nsleep_restart()

No more users.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170607084241.28657-8-viro@ZenIV.linux.org.uk

hrtimers/posix-timers: Merge nanosleep timespec copyout logics into a new helper

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170607084241.28657-7-viro@ZenIV.linux.org.uk

hrtimer_nanosleep(): Pass rmtp in restart_block

Store the pointer to the timespec which gets updated with the remaining
time in the restart block and remove the function argument.

[ tglx: Added changelog ]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170607084241.28657-3-viro@ZenIV.linux.org.uk

time: Change k_clock nsleep() to use timespec64

struct timespec is not y2038 safe on 32 bit machines. Replace uses of
struct timespec with struct timespec64 in the kernel.

The syscall interfaces themselves will be changed in a separate series.

Note that the restart_block parameter for nanosleep has also been left
unchanged and will be part of syscall series noted above.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: y2038@lists.linaro.org
Cc: john.stultz@linaro.org
Cc: arnd@arndb.de
Link: http://lkml.kernel.org/r/1490555058-4603-8-git-send-email-deepa.kernel@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Remove hrtimer_peek_ahead_timers() leftovers

This function was removed in commit c6eb3f70d448 (hrtimer: Get rid of
hrtimer softirq, 2015-04-14) but the prototype wasn't ever deleted.

Delete it now.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Link: http://lkml.kernel.org/r/20170317010814.2591-1-sboyd@codeaurora.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

sched/headers, hrtimer: Remove the <linux/wait.h> include from <linux/hrtimer.h>

In our quest to simplify <linux/sched.h>'s header dependencies, remove
the <linux/wait.h> inclusion from <linux/hrtimer.h> - which does
not appear to be necessary, as hrtimer.h does not use waitqueues.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

time: Remove CONFIG_TIMER_STATS

Currently CONFIG_TIMER_STATS exposes process information across namespaces:

kernel/time/timer_list.c print_timer():

SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);

/proc/timer_list:

#11: <0000000000000000>, hrtimer_wakeup, S:01, do_nanosleep, cron/2570

Given that the tracer can give the same information, this patch entirely
removes CONFIG_TIMER_STATS.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: linux-doc@vger.kernel.org
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Xing Gao <xgao01@email.wm.edu>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jessica Frazelle <me@jessfraz.com>
Cc: kernel-hardening@lists.openwall.com
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Michal Marek <mmarek@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-api@vger.kernel.org
Cc: Arjan van de Ven <arjan@linux.intel.com>
Link: http://lkml.kernel.org/r/20170208192659.GA32582@beast
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

ktime: Get rid of the union

ktime is a union because the initial implementation stored the time in
scalar nanoseconds on 64 bit machine and in a endianess optimized timespec
variant for 32bit machines. The Y2038 cleanup removed the timespec variant
and switched everything to scalar nanoseconds. The union remained, but
become completely pointless.

Get rid of the union and just keep ktime_t as simple typedef of type s64.

The conversion was done with coccinelle and some manual mopping up.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>

hrtimer: Convert to hotplug state machine

Split out the clockevents callbacks instead of piggybacking them on
hrtimers.

This gets rid of a POST_DEAD user. See commit:

54e88fad223c ("sched: Make sure timers have migrated before killing the migration_thread")

We just move the callback state to the proper place in the state machine.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153337.485419196@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

timer: convert timer_slack_ns from unsigned long to u64

This patchset introduces a /proc/<pid>/timerslack_ns interface which
would allow controlling processes to be able to set the timerslack value
on other processes in order to save power by avoiding wakeups (Something
Android currently does via out-of-tree patches).

The first patch tries to fix the internal timer_slack_ns usage which was
defined as a long, which limits the slack range to ~4 seconds on 32bit
systems. It converts it to a u64, which provides the same basically
unlimited slack (500 years) on both 32bit and 64bit machines.

The second patch introduces the /proc/<pid>/timerslack_ns interface
which allows the full 64bit slack range for a task to be read or set on
both 32bit and 64bit machines.

With these two patches, on a 32bit machine, after setting the slack on
bash to 10 seconds:

$ time sleep 1

real 0m10.747s
user 0m0.001s
sys 0m0.005s

The first patch is a little ugly, since I had to chase the slack delta
arguments through a number of functions converting them to u64s. Let me
know if it makes sense to break that up more or not.

Other than that things are fairly straightforward.

This patch (of 2):

The timer_slack_ns value in the task struct is currently a unsigned
long. This means that on 32bit applications, the maximum slack is just
over 4 seconds. However, on 64bit machines, its much much larger (~500
years).

This disparity could make application development a little (as well as
the default_slack) to a u64. This means both 32bit and 64bit systems
have the same effective internal slack range.

Now the existing ABI via PR_GET_TIMERSLACK and PR_SET_TIMERSLACK specify
the interface as a unsigned long, so we preserve that limitation on
32bit systems, where SET_TIMERSLACK can only set the slack to a unsigned
long value, and GET_TIMERSLACK will return ULONG_MAX if the slack is
actually larger then what can be stored by an unsigned long.

This patch also modifies hrtimer functions which specified the slack
delta as a unsigned long.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Oren Laadan <orenl@cellrox.com>
Cc: Ruchi Kandoi <kandoiruchi@google.com>
Cc: Rom Lemarchand <romlem@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

hrtimer: Revert CLOCK_MONOTONIC_RAW support

Revert commits:
a6e707ddbdf1: KVM: arm/arm64: timer: Switch to CLOCK_MONOTONIC_RAW
9006a01829a5: hrtimer: Catch illegal clockids
9c808765e88e: hrtimer: Add support for CLOCK_MONOTONIC_RAW

Marc found out, that there are fundamental issues with that patch series
because __hrtimer_get_next_event() and hrtimer_forward() need support for
CLOCK_MONOTONIC_RAW. Nothing which is easily fixed, so revert the whole lot.

Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/56D6CEF0.8060607@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Add support for CLOCK_MONOTONIC_RAW

The KVM/ARM timer implementation arms a hrtimer when a vcpu is
blocked (usually because it is waiting for an interrupt)
while its timer is going to kick in the future.

It is essential that this timer doesn't get adjusted, or the
guest will end up being woken-up at the wrong time (NTP running
on the host seems to confuse the hell out of some guests).

In order to allow this, let's add CLOCK_MONOTONIC_RAW support
to hrtimer (it is so far only supported for posix timers). It also
has the (limited) benefit of fixing de0421d53bfb ("mac80211_hwsim:
shuffle code to prepare for dynamic radios"), which already uses
this functionnality without realizing wasn't implemented (just being
lucky...).

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Tomasz Nowicki <tn@semihalf.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Link: http://lkml.kernel.org/r/1452879670-16133-2-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Handle remaining time proper for TIME_LOW_RES

If CONFIG_TIME_LOW_RES is enabled we add a jiffie to the relative timeout to
prevent short sleeps, but we do not account for that in interfaces which
retrieve the remaining time.

Helge observed that timerfd can return a remaining time larger than the
relative timeout. That's not expected and breaks userland test programs.

Store the information that the timer was armed relative and provide functions
to adjust the remaining time. To avoid bloating the hrtimer struct make state
a u8, which as a bonus results in better code on x86 at least.

Reported-and-tested-by: Helge Deller <deller@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: linux-m68k@lists.linux-m68k.org
Cc: dhowells@redhat.com
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20160114164159.273328486@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

timer: Minimize nohz off overhead

If nohz is disabled on the kernel command line the [hr]timer code
still calls wake_up_nohz_cpu() and tick_nohz_full_cpu(), a pretty
pointless exercise. Cache nohz_active in [hr]timer per cpu bases and
avoid the overhead.

Before:
48.10% hog [.] main
15.25% [kernel] [k] _raw_spin_lock_irqsave
9.76% [kernel] [k] _raw_spin_unlock_irqrestore
6.50% [kernel] [k] mod_timer
6.44% [kernel] [k] lock_timer_base.isra.38
3.87% [kernel] [k] detach_if_pending
3.80% [kernel] [k] del_timer
2.67% [kernel] [k] internal_add_timer
1.33% [kernel] [k] __internal_add_timer
0.73% [kernel] [k] timerfn
0.54% [kernel] [k] wake_up_nohz_cpu

After:
48.73% hog [.] main
15.36% [kernel] [k] _raw_spin_lock_irqsave
9.77% [kernel] [k] _raw_spin_unlock_irqrestore
6.61% [kernel] [k] lock_timer_base.isra.38
6.42% [kernel] [k] mod_timer
3.90% [kernel] [k] detach_if_pending
3.76% [kernel] [k] del_timer
2.41% [kernel] [k] internal_add_timer
1.39% [kernel] [k] __internal_add_timer
0.76% [kernel] [k] timerfn

We probably should have a cached value for nohz full in the per cpu
bases as well to avoid the cpumask check. The base cache line is hot
already, the cpumask not necessarily.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joonwoo Park <joonwoop@codeaurora.org>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>
Link: http://lkml.kernel.org/r/20150526224512.207378134@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

timer: Reduce timer migration overhead if disabled

Eric reported that the timer_migration sysctl is not really nice
performance wise as it needs to check at every timer insertion whether
the feature is enabled or not. Further the check does not live in the
timer code, so we have an extra function call which checks an extra
cache line to figure out that it is disabled.

We can do better and store that information in the per cpu (hr)timer
bases. I pondered to use a static key, but that's a nightmare to
update from the nohz code and the timer base cache line is hot anyway
when we select a timer base.

The old logic enabled the timer migration unconditionally if
CONFIG_NO_HZ was set even if nohz was disabled on the kernel command
line.

With this modification, we start off with migration disabled. The user
visible sysctl is still set to enabled. If the kernel switches to NOHZ
migration is enabled, if the user did not disable it via the sysctl
prior to the switch. If nohz=off is on the kernel command line,
migration stays disabled no matter what.

Before:
47.76% hog [.] main
14.84% [kernel] [k] _raw_spin_lock_irqsave
9.55% [kernel] [k] _raw_spin_unlock_irqrestore
6.71% [kernel] [k] mod_timer
6.24% [kernel] [k] lock_timer_base.isra.38
3.76% [kernel] [k] detach_if_pending
3.71% [kernel] [k] del_timer
2.50% [kernel] [k] internal_add_timer
1.51% [kernel] [k] get_nohz_timer_target
1.28% [kernel] [k] __internal_add_timer
0.78% [kernel] [k] timerfn
0.48% [kernel] [k] wake_up_nohz_cpu

After:
48.10% hog [.] main
15.25% [kernel] [k] _raw_spin_lock_irqsave
9.76% [kernel] [k] _raw_spin_unlock_irqrestore
6.50% [kernel] [k] mod_timer
6.44% [kernel] [k] lock_timer_base.isra.38
3.87% [kernel] [k] detach_if_pending
3.80% [kernel] [k] del_timer
2.67% [kernel] [k] internal_add_timer
1.33% [kernel] [k] __internal_add_timer
0.73% [kernel] [k] timerfn
0.54% [kernel] [k] wake_up_nohz_cpu


Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Joonwoo Park <joonwoop@codeaurora.org>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>
Link: http://lkml.kernel.org/r/20150526224512.127050787@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Allow hrtimer::function() to free the timer

Currently an hrtimer callback function cannot free its own timer
because __run_hrtimer() still needs to clear HRTIMER_STATE_CALLBACK
after it. Freeing the timer would result in a clear use-after-free.

Solve this by using a scheme similar to regular timers; track the
current running timer in hrtimer_clock_base::running.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: ktkhai@parallels.com
Cc: rostedt@goodmis.org
Cc: juri.lelli@gmail.com
Cc: pang.xunlei@linaro.org
Cc: wanpeng.li@linux.intel.com
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20150611124743.471563047@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Remove HRTIMER_STATE_MIGRATE

I do not understand HRTIMER_STATE_MIGRATE. Unless I am totally
confused it looks buggy and simply unneeded.

migrate_hrtimer_list() sets it to keep hrtimer_active() == T, but this
is not enough: this can fool, say, hrtimer_is_queued() in
dequeue_signal().

Can't migrate_hrtimer_list() simply use HRTIMER_STATE_ENQUEUED?
This fixes the race and we can kill STATE_MIGRATE.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: ktkhai@parallels.com
Cc: rostedt@goodmis.org
Cc: juri.lelli@gmail.com
Cc: pang.xunlei@linaro.org
Cc: wanpeng.li@linux.intel.com
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20150611124743.072387650@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimers: Make sure hrtimer_resolution is unsigned int

... in the !CONFIG_HIGH_RES_TIMERS case too. And thus fix warnings like
this one:

net/sched/sch_api.c: In function ‘psched_show’:
net/sched/sch_api.c:1891:6: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 6 has type ‘long int’ [-Wformat=]
(u32)NSEC_PER_SEC / hrtimer_resolution);

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1433583000-32090-1-git-send-email-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Remove hrtimer_start() return value

No user was ever interested whether the timer was active or not when
it was started. All abusers of the return value are gone, so get rid
of it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203503.483556394@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Make hrtimer_start() a inline wrapper

No point for an extra export just to set the extra argument of
hrtimer_start_range_ns() to 0.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203502.808544539@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Get rid of __hrtimer_start_range_ns()

No more callers. Remove the leftovers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203502.707871492@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

tick: Nohz: Rework next timer evaluation

The evaluation of the next timer in the nohz code is based on jiffies
while all the tick internals are nano seconds based. We have also to
convert hrtimer nanoseconds to jiffies in the !highres case. That's
just wrong and introduces interesting corner cases.

Turn it around and convert the next timer wheel timer expiry and the
rcu event to clock monotonic and base all calculations on
nanoseconds. That identifies the case where no timer is pending
clearly with an absolute expiry value of KTIME_MAX.

Makes the code more readable and gets rid of the jiffies magic in the
nohz code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Link: http://lkml.kernel.org/r/20150414203502.184198593@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Get rid of hrtimer softirq

hrtimer softirq is a leftover from the initial implementation and
serves only the purpose to handle the enqueueing of already expired
timers in the high resolution timer mode. We discussed whether we
change the return value and force all start sites to handle that the
timer is already expired, but that would be a Herculean task and I'm
not sure whether its a good idea to enforce that handling on
everyone.

A simpler solution is to enforce a timer interrupt instead of raising
and scheduling a softirq. Just use the existing infrastructure to do
so and remove all the softirq leftovers.

The HRTIMER softirq enum is now unused, but kept around because trace
parsers rely on the existing numbering.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.840834708@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Keep pointer to first timer and simplify __remove_hrtimer()

__remove_hrtimer() needs to evaluate the expiry time to figure out
whether the timer which is removed is eventually the first expiring
timer on the cpu. Keep a pointer to it, which is lazily updated, so we
can avoid the evaluation dance and retrieve the information from there.

Generates slightly better code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.752838019@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Align the hrtimer clock bases as well

We don't use cacheline_align here because that might waste lot of
space on 32bit machine with 64 bytes cachelines and on 64bit machines
with 128 bytes cachelines.

The size of struct hrtimer_clock_base is 64byte on 64bit and 32byte on
32bit machines. So we utilize the cache lines proper.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.498165771@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Cache line align the hrtimer cpu base

We really want that data structure to start at a cache line boundary.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.417597627@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Use bits for various boolean indicators

No point in wasting 12 byte storage space. Generates better code as well.

Text size reduction:
x8664 -64, i386 -16, ARM -132, ARM64 -0, power64 -48

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.227955358@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Make offset update smarter

On every tick/hrtimer interrupt we update the offset variables of the
clock bases. That's silly because these offsets change very seldom.

Add a sequence counter to the time keeping code which keeps track of
the offset updates (clock_was_set()). Have a sequence cache in the
hrtimer cpu bases to evaluate whether the offsets must be updated or
not. This allows us later to avoid pointless cacheline pollution.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20150414203501.132820245@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>

hrtimer: Get rid of softirq time

The softirq time field in the clock bases is an optimization from the
early days of hrtimers. It provides a coarse "jiffies" like time
mostly for self rearming timers.

But that comes with a price:
- Larger code size
- Extra storage space
- Duplicated functions with really small differences

The benefit of this is optimization is marginal for contemporary
systems.

Consolidate everything on the high resolution timer
implementation. This makes further optimizations possible.

Text size reduction:
x8664 -95, i386 -356, ARM -148, ARM64 -40, power64 -16

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203501.039977424@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Make the statistics fields smaller

No point in having usigned long for /proc/timer_list statistics. Make
them unsigned int.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203500.959773467@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Get rid of hrtimer_get_res()

The resolution is directly accessible now. So its simpler just to fill
in the values of the timespec and be done with it.

Text size reduction (combined with "hrtimer: Get rid of the resolution
field in hrtimer_clock_base"):
x8664 -61, i386 -221, ARM -60, power64 -48

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203500.879888080@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Get rid of the resolution field in hrtimer_clock_base

The field has no value because all clock bases have the same
resolution. The resolution only changes when we switch to high
resolution timer mode. We can evaluate that from a single static
variable as well. In the !HIGHRES case its simply a constant.

Export the variable, so we can simplify the usage sites.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203500.645454122@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Document hrtimer_forward[_now]() proper

Document the calling context conditions.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150413210035.178751779@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Prevent stale expiry time in hrtimer_interrupt()

hrtimer_interrupt() has the following subtle issue:

hrtimer_interrupt()
lock(cpu_base);
expires_next = KTIME_MAX;

expire_timers(CLOCK_MONOTONIC);
expires = get_next_timer(CLOCK_MONOTONIC);
if (expires < expires_next)
expires_next = expires;

expire_timers(CLOCK_REALTIME);
unlock(cpu_base);
wakeup()
hrtimer_start(CLOCK_MONOTONIC, newtimer);
lock(cpu_base();
expires = get_next_timer(CLOCK_REALTIME);
if (expires < expires_next)
expires_next = expires;

So because we already evaluated the next expiring timer of
CLOCK_MONOTONIC we ignore that the expiry time of newtimer might be
earlier than the overall next expiry time in hrtimer_interrupt().

To solve this, remove the caching of the next expiry value from
hrtimer_interrupt() and reevaluate all active clock bases for the next
expiry value. To avoid another code duplication, create a shared
evaluation function and use it for hrtimer_get_next_event(),
hrtimer_force_reprogram() and hrtimer_interrupt().

There is another subtlety in this mechanism:

While hrtimer_interrupt() is running, we want to avoid to touch the
hardware device because we will reprogram it anyway at the end of
hrtimer_interrupt(). This works nicely for hrtimers which get rearmed
via the HRTIMER_RESTART mechanism, because we drop out when the
callback on that CPU is running. But that fails, if a new timer gets
enqueued like in the example above.

This has another implication: While hrtimer_interrupt() is running we
refuse remote enqueueing of timers - see hrtimer_interrupt() and
hrtimer_check_target().

hrtimer_interrupt() tries to prevent this by setting cpu_base->expires
to KTIME_MAX, but that fails if a new timer gets queued.

Prevent both the hardware access and the remote enqueue
explicitely. We can loosen the restriction on the remote enqueue now
due to reevaluation of the next expiry value, but that needs a
seperate patch.

Folded in a fix from Vignesh Radhakrishnan.

Reported-and-tested-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Based-on-patch-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: vigneshr@codeaurora.org
Cc: john.stultz@linaro.org
Cc: viresh.kumar@linaro.org
Cc: fweisbec@gmail.com
Cc: cl@linux.com
Cc: stuart.w.hayes@gmail.com
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1501202049190.5526@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

time: Consolidate the time accessor prototypes

Right now we have time related prototypes in 3 different header
files. Move it to a single timekeeping header file and move the core
internal stuff into a core private header.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

ktime: Sanitize ktime_to_us/ms conversion

With the plain nanoseconds based ktime_t we can simply use
ktime_divns() instead of going through loops and hoops of
timespec/timeval conversion.

Reported-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

hrtimer: Cleanup hrtimer accessors to the timekepeing state

Rather then having two similar but totally different implementations
that provide timekeeping state to the hrtimer code, try to unify the
two implementations to be more simliar.

Thus this clarifies ktime_get_update_offsets to
ktime_get_update_offsets_now and changes get_xtime... to
ktime_get_update_offsets_tick.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

hrtimer: Store cpu-number in struct hrtimer_cpu_base

In lowres mode, hrtimers are serviced by the tick instead of a clock
event. Now it works well as long as the tick stays periodic but we
must also make sure that the hrtimers are serviced in dynticks mode.

Part of that job consist in kicking a dynticks hrtimer target in order
to make it reconsider the next tick to schedule to correctly handle the
hrtimer's expiring time. And that part isn't handled by the hrtimers
subsystem.

To prepare for fixing this, we need __hrtimer_start_range_ns() to be
able to resolve the CPU target associated to a hrtimer's object
'cpu_base' so that the kick can be centralized there.

So lets store it in the 'struct hrtimer_cpu_base' to resolve the CPU
without overhead. It is set once at CPU's online notification.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1403393357-2070-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Rearrange comments in the order struct members are declared

Rearrange kernel doc comments in the order members of struct hrtimer are
declared.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: fweisbec@gmail.com
Cc: trivial@kernel.org
Link: http://lkml.kernel.org/r/1db1a3cfbe8a9ea49396af75c6ac04a2e67e3ab0.1395226248.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Add hrtimer support for CLOCK_TAI

Add hrtimer support for CLOCK_TAI, as well as posix timer interfaces.

Signed-off-by: John Stultz <john.stultz@linaro.org>

timekeeping: Provide hrtimer update function

To finally fix the infamous leap second issue and other race windows
caused by functions which change the offsets between the various time
bases (CLOCK_MONOTONIC, CLOCK_REALTIME and CLOCK_BOOTTIME) we need a
function which atomically gets the current monotonic time and updates
the offsets of CLOCK_REALTIME and CLOCK_BOOTTIME with minimalistic
overhead. The previous patch which provides ktime_t offsets allows us
to make this function almost as cheap as ktime_get() which is going to
be replaced in hrtimer_interrupt().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/1341960205-56738-7-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Provide clock_was_set_delayed()

clock_was_set() cannot be called from hard interrupt context because
it calls on_each_cpu().

For fixing the widely reported leap seconds issue it is necessary to
call it from hard interrupt context, i.e. the timer tick code, which
does the timekeeping updates.

Provide a new function which denotes it in the hrtimer cpu base
structure of the cpu on which it is called and raise the hrtimer
softirq. We then execute the clock_was_set() notificiation from
softirq context in run_hrtimer_softirq(). The hrtimer softirq is
rarely used, so polling the flag there is not a performance issue.

[ tglx: Made it depend on CONFIG_HIGH_RES_TIMERS. We really should get
rid of all this ifdeffery ASAP ]

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Reported-by: Jan Engelhardt <jengelh@inai.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1341960205-56738-2-git-send-email-johnstul@us.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

treewide: fix kernel-doc warnings

Fix 'make htmldocs' warnings:

Warning(/include/linux/hrtimer.h:153): No description found for
parameter 'clockid'
Warning(/include/linux/device.h:604): Excess struct/union/enum/typedef
member 'of_match' description in 'device'
Warning(/include/net/sock.h:349): Excess struct/union/enum/typedef
member 'sk_rmem_alloc' description in 'sock'

Signed-off-by: Vitaliy Ivanov <vitalivanov@gmail.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Fix some kernel-doc warnings

Fix 'make htmldocs' warnings:

Warning(/include/linux/hrtimer.h:153): No description found for parameter 'clockid'
Warning(/include/linux/device.h:604): Excess struct/union/enum/typedef member 'of_match' description in 'device'
Warning(/include/net/sock.h:349): Excess struct/union/enum/typedef member 'sk_rmem_alloc' description in 'sock'

Signed-off-by: Vitaliy Ivanov <vitalivanov@gmail.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

hrtimers: Reorder clock bases

The ordering of the clock bases is historical due to the
CLOCK_REALTIME and CLOCK_MONOTONIC constants. Now the hrtimer bases
have their own enumeration due to the gap between CLOCK_MONOTONIC and
CLOCK_BOOTTIME. So we can be more clever as most timers end up on the
CLOCK_MONOTONIC base due to the virtue of POSIX declaring that
relative CLOCK_REALTIME timers are not affected by time changes. In
desktop environments this is slowly changing as applications switch to
absolute timers, but I've observed empty CLOCK_REALTIME bases often
enough. There is no performance penalty or overhead when
CLOCK_REALTIME timers are active, but in case they are not we don't
skip over a full cache line.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>

hrtimers: Avoid touching inactive timer bases

Instead of iterating over all possible timer bases avoid it by marking
the active bases in the cpu base.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>

hrtimers: Make struct hrtimer_cpu_base layout less stupid

In the HIGHRES=y case we access the members at the end of struct
hrtimer_cpu_base first and then the one at the beginning. Move the
hrtimer data to front, so we have linear progressing access.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>

timerfd: Manage cancelable timers in timerfd

Peter is concerned about the extra scan of CLOCK_REALTIME_COS in the
timer interrupt. Yes, I did not think about it, because the solution
was so elegant. I didn't like the extra list in timerfd when it was
proposed some time ago, but with a rcu based list the list walk it's
less horrible than the original global lock, which was held over the
list iteration.

Requested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>

timerfd: Allow timers to be cancelled when clock was set

Some applications must be aware of clock realtime being set
backward. A simple example is a clock applet which arms a timer for
the next minute display. If clock realtime is set backward then the
applet displays a stale time for the amount of time which the clock
was set backwards. Due to that applications poll the time because we
don't have an interface.

Extend the timerfd interface by adding a flag which puts the timer
onto a different internal realtime clock. All timers on this clock are
expired whenever the clock was set.

The timerfd core records the monotonic offset when the timer is
created. When the timer is armed, then the current offset is compared
to the previous recorded offset. When it has changed, then
timerfd_settime returns -ECANCELED. When a timer is read the offset is
compared and if it changed -ECANCELED returned to user space. Periodic
timers are not rearmed in the cancelation case.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Chris Friesen <chris.friesen@genband.com>
Tested-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Davide Libenzi <davidel@xmailserver.org>
Reviewed-by: Alexander Shishkin <virtuoso@slind.org>
Link: http://lkml.kernel.org/r/%3Calpine.LFD.2.02.1104271359580.3323%40ionos%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimers: Prepare for cancel on clock was set timers

Make clock_was_set() unconditional and rename hres_timers_resume to
hrtimers_resume. This is a preparatory patch for hrtimers which are
cancelled when clock realtime was set.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Update hrtimer->state documentation

We changed some of the state bits and combinations thereof over time,
but never updated the documentation.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

timers: Add CLOCK_BOOTTIME hrtimer base

CLOCK_MONOTONIC stops while the system is in suspend. This is because
to applications system suspend is invisible. However, there is a
growing set of applications that are wanting to be suspend-aware,
but do not want to deal with the complications of CLOCK_REALTIME
(which might jump around if settimeofday is called).

For these applications, I propose a new clockid: CLOCK_BOOTTIME.
CLOCK_BOOTTIME is idential to CLOCK_MONOTONIC, except it also
includes any time spent in suspend.

This patch add hrtimer base for CLOCK_BOOTTIME, using
get_monotonic_boottime/ktime_get_boottime, to allow
in kernel users to set timers against.

CC: Jamie Lokier <jamie@shareable.org>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Alexander Shishkin <virtuoso@slind.org>
CC: Arve Hjønnevåg <arve@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

time: Introduce get_monotonic_boottime and ktime_get_boottime

This adds new functions that return the monotonic time since boot
(in other words, CLOCK_MONOTONIC + suspend time).

CC: Jamie Lokier <jamie@shareable.org>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Alexander Shishkin <virtuoso@slind.org>
CC: Arve Hjønnevåg <arve@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

hrtimers: extend hrtimer base code to handle more then 2 clockids

The hrtimer code is written mainly with CLOCK_REALTIME and CLOCK_MONOTONIC
in mind. These are clockids 0 and 1 resepctively. However, if we are
to introduce any new hrtimer bases, using new clockids, we have to skip
the cputimers (clockids 2,3) as well as other clockids that may not impelement
timers.

This patch adds a little bit of indirection between the clockid and
the base, so that we can extend the base by one when we add
a new clockid at number 7 or so.

CC: Jamie Lokier <jamie@shareable.org>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Alexander Shishkin <virtuoso@slind.org>
CC: Arve Hjønnevåg <arve@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

hrtimer.h: fix kernel-doc warning

Fix new kernel-doc notation warning in hrtimer.h:

Warning(include/linux/hrtimer.h:150): Excess struct/union/enum/typedef member 'first' description in 'hrtimer_clock_base'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

hrtimers: Convert hrtimers to use timerlist infrastructure

Converts the hrtimer code to use the new timerlist infrastructure

Signed-off-by: John Stultz <john.stultz@linaro.org>
LKML Reference: <1290136329-18291-3-git-send-email-john.stultz@linaro.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
CC: Alessandro Zummo <a.zummo@towertech.it>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Richard Cochran <richardcochran@gmail.com>

hrtimer: Remove stale comment on curr_timer

curr_timer doesn't resident in struct hrtimer_cpu_base anymore.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
LKML-Reference: <1287892253-2587-1-git-send-email-yong.zhang0@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimers: Provide schedule_hrtimeout for CLOCK_REALTIME

The current version of schedule_hrtimeout() always uses the
monotonic clock. Some system calls such as mq_timedsend()
and mq_timedreceive(), however, require the use of the wall
clock due to the definition of the system call.

This patch provides the infrastructure to use schedule_hrtimeout()
with a CLOCK_REALTIME timer.

Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Tested-by: Pradyumna Sampath <pradysam@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Veen <arjan@infradead.org>
LKML-Reference: <20100402204331.167439615@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimers: Convert to raw_spinlocks

Convert locks which cannot be sleeping locks in preempt-rt to
raw_spinlocks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@elte.hu>

hrtimer: move timer stats helper functions to hrtimer.c

There is no reason to make timer_stats_hrtimer_set_start_info and
friends visible to the rest of the kernel. So move all of them to
hrtimer.c. Also make timer_stats_hrtimer_set_start_info a static
inline function so it gets inlined and we avoid another function call.
Based on a patch by Thomas Gleixner.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
LKML-Reference: <20091210095629.GC4144@osiris.boeblingen.de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Tune hrtimer_interrupt hang logic

The hrtimer_interrupt hang logic adjusts min_delta_ns based on the
execution time of the hrtimer callbacks.

This is error-prone for virtual machines, where a guest vcpu can be
scheduled out during the execution of the callbacks (and the callbacks
themselves can do operations that translate to blocking operations in
the hypervisor), which in can lead to large min_delta_ns rendering the
system unusable.

Replace the current heuristics with something more reliable. Allow the
interrupt code to try 3 times to catch up with the lost time. If that
fails use the total time spent in the interrupt handler to defer the
next timer interrupt so the system can catch up with other things
which got delayed. Limit that deferment to 100ms.

The retry events and the maximum time spent in the interrupt handler
are recorded and exposed via /proc/timer_list

Inspired by a patch from Marcelo.

Reported-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: kvm@vger.kernel.org

hrtimer: Fix /proc/timer_list regression

commit 507e1231 (timer stats: Optimize by adding quick check to avoid
function calls) introduced a regression in /proc/timer_list.

/proc/timer_list shows now
#0: <c27d46b0>, tick_sched_timer, S:01, <(null)>, /-1
instead of
#0: <c27d46b0>, tick_sched_timer, S:01, hrtimer_start, swapper/0

Revert the hrtimer quick check for now. The optimization needs more
thought, but this is neither 2.6.32-rc7 nor stable material.

[ tglx: - Removed unrelated changes from the original patch
- Prevent unneccesary call to timer_stats_update_stats
- massaged the changelog ]

Signed-off-by: Feng Tang <feng.tang@intel.com>
LKML-Reference: <alpine.LFD.2.00.0911181933540.24119@localhost.localdomain>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: stable@kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: Remove cb_entry from struct hrtimer

It's unused, remove it.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>

timer stats: fix quick check optimization

git commit 507e1231 "timer stats: Optimize by adding quick check to
avoid function calls" added one wrong check so that one unnecessary
function call isn't elimated.

time_stats_account_hrtimer() checks if timer->start_pid isn't
initialized in order to find out if timer_stats_update_stats() should
be called. However start_pid is initialized with -1 instead of 0, so
that the function call always happens.

Check timer->start_site like in timer_stats_account_timer() to fix
this.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

timer stats: Optimize by adding quick check to avoid function calls

When the kernel is configured with CONFIG_TIMER_STATS but timer
stats are runtime disabled we still get calls to
__timer_stats_timer_set_start_info which initializes some
fields in the corresponding struct timer_list.

So add some quick checks in the the timer stats setup functions
to avoid function calls to __timer_stats_timer_set_start_info
when timer stats are disabled.

In an artificial workload that does nothing but playing ping
pong with a single tcp packet via loopback this decreases cpu
consumption by 1 - 1.5%.

This is part of a modified function trace output on SLES11:

perl-2497 [00] 28630647177732388 [+ 125]: sk_reset_timer <-tcp_v4_rcv
perl-2497 [00] 28630647177732513 [+ 125]: mod_timer <-sk_reset_timer
perl-2497 [00] 28630647177732638 [+ 125]: __timer_stats_timer_set_start_info <-mod_timer
perl-2497 [00] 28630647177732763 [+ 125]: __mod_timer <-mod_timer
perl-2497 [00] 28630647177732888 [+ 125]: __timer_stats_timer_set_start_info <-__mod_timer
perl-2497 [00] 28630647177733013 [+ 93]: lock_timer_base <-__mod_timer

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mustafa Mesanovic <mustafa.mesanovic@de.ibm.com>
Cc: Arjan van de Ven <arjan@infradead.org>
LKML-Reference: <20090623153811.GA4641@osiris.boeblingen.de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

clocksource: prevent selection of low resolution clocksourse also for nohz=on

commit 3f68535adad (clocksource: sanity check sysfs clocksource
changes) prevents selection of non high resolution capable
clocksources when high resolution mode is active, but did not take
into account that the same rules apply for highres=off nohz=on.

Check the tick device mode instead of hrtimer_hres_active() to verify
whether the system needs to be protected from a switch to jiffies or
other non highres capable clock sources.

Reported-by: Luming Yu <luming.yu@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

clocksource: sanity check sysfs clocksource changes

Thomas, Andrew and Ingo pointed out that we don't have any safety checks
in the clocksource sysfs entries to make sure sysadmins don't try to
change the clocksource to a non high-res timer capable clocksource (such
as jiffies) when high-res timers (HRT) is enabled. Doing so will likely
hang a system.

Correct this by filtering non HRT clocksources from available_clocksources
and not accepting non HRT clocksources with HRT enabled.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

timers: Framework for identifying pinned timers

* Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-04-16 12:11:36]:

This patch creates a new framework for identifying cpu-pinned timers
and hrtimers.

This framework is needed because pinned timers are expected to fire on
the same CPU on which they are queued. So it is essential to identify
these and not migrate them, in case there are any.

For regular timers, the currently existing add_timer_on() can be used
queue pinned timers and subsequently mod_timer_pinned() can be used
to modify the 'expires' field.

For hrtimers, new modes HRTIMER_ABS_PINNED and HRTIMER_REL_PINNED are
added to queue cpu-pinned hrtimer.

[ tglx: use .._PINNED mode argument instead of creating tons of new
functions ]

Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: fix rq->lock inversion (again)

It appears I inadvertly introduced rq->lock recursion to the
hrtimer_start() path when I delegated running already expired
timers to softirq context.

This patch fixes it by introducing a __hrtimer_start_range_ns()
method that will not use raise_softirq_irqoff() but
__raise_softirq_irqoff() which avoids the wakeup.

It then also changes schedule() to check for pending softirqs and
do the wakeup then, I'm not quite sure I like this last bit, nor
am I convinced its really needed.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus@samba.org
LKML-Reference: <20090313112301.096138802@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

hrtimer: removing all ur callback modes

Impact: cleanup, move all hrtimer processing into hardirq context

This is an attempt at removing some of the hrtimer complexity by
reducing the number of callback modes to 1.

This means that all hrtimer callback functions will be ran from HARD-irq
context.

I went through all the 30 odd hrtimer callback functions in the kernel
and saw only one that I'm not quite sure of, which is the one in
net/can/bcm.c - hence I'm CC-ing the folks responsible for that code.

Furthermore, the hrtimer core now calls callbacks directly with IRQs
disabled in case you try to enqueue an expired timer. If this timer is a
periodic timer (which should use hrtimer_forward() to advance its time)
then it might be possible to end up in an inf. recursive loop due to the
fact that hrtimer_forward() doesn't round up to the next timer
granularity, and therefore keeps on calling the callback - obviously
this needs a fix.

Aside from that, this seems to compile and actually boot on my dual core
test box - although I'm sure there are some bugs in, me not hitting any
makes me certain :-)

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

hrtimer: clean up unused callback modes

Impact: cleanup

git grep HRTIMER_CB_IRQSAFE revealed half the callback modes are actually
unused.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix accidental implicit cast in HR-timer conversion

Fix the hrtimer_add_expires_ns() function. It should take a 'u64 ns' argument,
but rather takes an 'unsigned long ns' argument - which might only be 32-bits.

On FRV, this results in the kernel locking up because hrtimer_forward() passes
the result of a 64-bit multiplication to this function, for which the compiler
discards the top 32-bits - something that didn't happen when ktime_add_ns() was
called directly.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

hrtimers: add missing docbook comments to struct hrtimer

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

DECLARE_PER_CPU needs linux/percpu.h

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

rangetimer: fix x86 build failure for the !HRTIMERS case

the timer peek function was on the wrong side of an ifdef,
breaking for the !HRTIMERs case. Just provide an empty inline
for that case since it doesn't make sense in that scenario.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

hrtimer: prevent migration of per CPU hrtimers

Impact: per CPU hrtimers can be migrated from a dead CPU

The hrtimer code has no knowledge about per CPU timers, but we need to
prevent the migration of such timers and warn when such a timer is
active at migration time.

Explicitely mark the timers as per CPU and use a more understandable
mode descriptor for the interrupts safe unlocked callback mode, which
is used by hrtimer_sleeper and the scheduler code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: mark migration state

Impact: during migration active hrtimers can be seen as inactive

The migration code removes the hrtimers from the queues of the dead
CPU and sets the state temporary to INACTIVE. The enqueue code sets it
to ACTIVE/PENDING again.

Prevent that the wrong state can be seen by using a separate migration
state bit.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: reorder struct hrtimer to save 8 bytes on 64bit builds

reorder struct hrtimer to save 8 bytes on 64 bit builds when
CONFIG_TIMER_STATS selected. (also removes 8 bytes from signal_struct)

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: remove hrtimer_clock_base::reprogram()

hrtimer_clock_base::reprogram() also appears to never
have been used, so remove it.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

hrtimer: remove hrtimer_clock_base::get_softirq_time()

Peter Zijlstra noticed this 8 months ago and I just noticed
it again.

hrtimer_clock_base::get_softirq_time() is currently unused
in the entire tree. In fact, looking at the logs, it appears
as if it was never used. Remove it.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

hrtimer: peek at the timer queue just before going idle

As part of going idle, we already look at the time of the next timer event to determine
which C-state to select etc.

This patch adds functionality that causes the timers that are past their
soft expire time, to fire at this time, before we calculate the next wakeup
time. This functionality will thus avoid wakeups by running timers before
going idle rather than specially waking up for it.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

hrtimer: incorporate feedback from Peter Zijlstra

(based on lkml review)
* use rt_task()
* task_nice() has a sign

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

hrtimer: add a hrtimer_start_range() function

this patch adds a _range version of hrtimer_start() so that range timers
can be created; the hrtimer_start() function is just a wrapper around this.

In addition, hrtimer_start_expires() will now preserve existing ranges.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

hrtimer: another build fix

More randconfig testing

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

hrtimer: fix build bug found by Ingo

in some randconfig configurations, hrtimers are used even though
the hrtimer config if off; and it broke the build due to some of
the new functions being on the wrong side of the ifdef.

This patch moves the functions to the other side of the ifdef, fixing
the build bug.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

hrtimer: turn hrtimers into range timers

this patch turns hrtimers into range timers; they have 2 expire points
1) the soft expire point
2) the hard expire point

the kernel will do it's regular best effort attempt to get the timer run
at the hard expire point. However, if some other time fires after the soft
expire point, the kernel now has the freedom to fire this timer at this point,
and thus grouping the events and preventing a power-expensive wakeup in the
future.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

hrtimer: rename the "expires" struct member to avoid accidental usage

To catch code that still touches the "expires" memory directly, rename it
to have the compiler complain rather than get nasty, hard to explain,
runtime behavior

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

hrtimer: add abstraction functions for accessing the "expires" member

In order to be able to turn hrtimers into range based, we need to provide
accessor functions for getting to the "expires" ktime_t member of the
struct hrtimer.

This patch adds a set of accessors for this purpose:
* hrtimer_set_expires
* hrtimer_set_expires_tv64
* hrtimer_add_expires
* hrtimer_add_expires_ns
* hrtimer_get_expires
* hrtimer_get_expires_tv64
* hrtimer_get_expires_ns
* hrtimer_expires_remaining
* hrtimer_start_expires

No users of these new accessors are added yet; these follow in later patches.
Hopefully this patch can even go into 2.6.27-rc so that the conversions will
not have a bottleneck in -next

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

select: Introduce a hrtimeout function

This patch adds a schedule_hrtimeout() function, to be used by select() and
poll() in a later patch. This function works similar to schedule_timeout()
in most ways, but takes a timespec rather than jiffies.

With a lot of contributions/fixes from Thomas

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: remove duplicate helper function

The helper function hrtimer_callback_running() is used in
kernel/hrtimer.c as well as in the updated net/can/bcm.c which now
supports hrtimers. Moving the helper function to hrtimer.h removes the
duplicate definition in the C-files.

Signed-off-by: Oliver Hartkopp <oliver@hartkopp.net>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

add hrtimer specific debugobjects code

hrtimers have now dynamic users in the network code. Put them under
debugobjects surveillance as well.

Add calls to the generic object debugging infrastructure and provide fixup
functions which allow to keep the system alive when recoverable problems have
been detected by the object debugging core code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

hrtimers: simplify lockdep handling

In order to avoid the false positive from lockdep, each per-cpu base->lock has
the separate lock class and migrate_hrtimers() uses double_spin_lock().

This is overcomplicated: except for migrate_hrtimers() we never take 2 locks
at once, and migrate_hrtimers() can use spin_lock_nested().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimer: fix *rmtp handling in hrtimer_nanosleep()

Spotted by Pavel Emelyanov and Alexey Dobriyan.

hrtimer_nanosleep() sets restart_block->arg1 = rmtp, but this rmtp points to
the local variable which lives in the caller's stack frame. This means that
if sys_restart_syscall() actually happens and it is interrupted as well, we
don't update the user-space variable, but write into the already dead stack
frame.

Introduced by commit 04c227140fed77587432667a574b14736a06dd7f
hrtimer: Rework hrtimer_nanosleep to make sys_compat_nanosleep easier

Change the callers to pass "__user *rmtp" to hrtimer_nanosleep(), and change
hrtimer_nanosleep() to use copy_to_user() to actually update *rmtp.

Small problem remains. man 2 nanosleep states that *rtmp should be written if
nanosleep() was interrupted (it says nothing whether it is OK to update *rmtp
if nanosleep returns 0), but (with or without this patch) we can dirty *rem
even if nanosleep() returns 0.

NOTE: this patch doesn't change compat_sys_nanosleep(), because it has other
bugs. Fixed by the next patch.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Pavel Emelyanov <xemul@sw.ru>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Toyo Abe <toyoa@mvista.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/hrtimer.h | 2 -
kernel/hrtimer.c | 51 +++++++++++++++++++++++++-----------------------
kernel/posix-timers.c | 14 +------------
3 files changed, 30 insertions(+), 37 deletions(-)

time: fix typo in comments

Fix typo in comments.

BTW: I have to fix coding style in arch/ia64/kernel/time.c also, otherwise
checkpatch.pl will be complaining.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Fix compilation of powerpc asm-offsets.c with old gcc

Commit ad7f71674ad7c3c4467e48f6ab9e85516dae2720 ("[POWERPC] Use a
sensible default for clock_getres() in the VDSO") corrected the clock
resolution reported by the VDSO clock_getres() but introduced another
problem in that older versions of gcc (gcc-4.0 and earlier) fail to
compile the new code in arch/powerpc/kernel/asm-offsets.c.

This fixes it by introducing a new MONOTONIC_RES_NSEC define in the
generic code which is equivalent to KTIME_MONOTONIC_RES but is just an
integer constant, not a ktime union.

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

timerfd: new timerfd API

This is the new timerfd API as it is implemented by the following patch:

int timerfd_create(int clockid, int flags);
int timerfd_settime(int ufd, int flags,
const struct itimerspec *utmr,
struct itimerspec *otmr);
int timerfd_gettime(int ufd, struct itimerspec *otmr);

The timerfd_create() API creates an un-programmed timerfd fd. The "clockid"
parameter can be either CLOCK_MONOTONIC or CLOCK_REALTIME.

The timerfd_settime() API give new settings by the timerfd fd, by optionally
retrieving the previous expiration time (in case the "otmr" parameter is not
NULL).

The time value specified in "utmr" is absolute, if the TFD_TIMER_ABSTIME bit
is set in the "flags" parameter. Otherwise it's a relative time.

The timerfd_gettime() API returns the next expiration time of the timer, or
{0, 0} if the timerfd has not been set yet.

Like the previous timerfd API implementation, read(2) and poll(2) are
supported (with the same interface). Here's a simple test program I used to
exercise the new timerfd APIs:

http://www.xmailserver.org/timerfd-test2.c

[akpm@linux-foundation.org: coding-style cleanups]
[akpm@linux-foundation.org: fix ia64 build]
[akpm@linux-foundation.org: fix m68k build]
[akpm@linux-foundation.org: fix mips build]
[akpm@linux-foundation.org: fix alpha, arm, blackfin, cris, m68k, s390, sparc and sparc64 builds]
[heiko.carstens@de.ibm.com: fix s390]
[akpm@linux-foundation.org: fix powerpc build]
[akpm@linux-foundation.org: fix sparc64 more]
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

timerfd: introduce a new hrtimer_forward_now() function

I think that advancing the timer against the timer's current "now" can be a
pretty common usage, so, w/out exposing hrtimer's internals, we add a new
hrtimer_forward_now() function.

Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

time: delete comments that refer to noexistent symbols

Function do_timer_interrupt_hook() don't take argument regs,
and structure hrtimer_sleeper don't have member cb_pending.
So delete comments refering to these symbols.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>

hrtimer: fixup the HRTIMER_CB_IRQSAFE_NO_SOFTIRQ fallback

Currently all highres=off timers are run from softirq context, but
HRTIMER_CB_IRQSAFE_NO_SOFTIRQ timers expect to run from irq context.

Fix this up by splitting it similar to the highres=on case.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: high-res preemption tick

Use HR-timers (when available) to deliver an accurate preemption tick.

The regular scheduler tick that runs at 1/HZ can be too coarse when nice
level are used. The fairness system will still keep the cpu utilisation 'fair'
by then delaying the task that got an excessive amount of CPU time but try to
minimize this by delivering preemption points spot-on.

The average frequency of this extra interrupt is sched_latency / nr_latency.
Which need not be higher than 1/HZ, its just that the distribution within the
sched_latency period is important.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

hrtimer: Rework hrtimer_nanosleep to make sys_compat_nanosleep easier

Pull the copy_to_user out of hrtimer_nanosleep and into the callers
(common_nsleep, sys_nanosleep) in preparation for converting
compat_sys_nanosleep to use hrtimers.

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Add a flag to indicate deferrable timers in /proc/timer_stats

Add a flag in /proc/timer_stats to indicate deferrable timers. This will
let developers/users to differentiate between types of tiemrs in
/proc/timer_stats.

Deferrable timer and normal timer will appear in /proc/timer_stats as below.
10D, 1 swapper queue_delayed_work_on (delayed_work_timer_fn)
10, 1 swapper queue_delayed_work_on (delayed_work_timer_fn)

Also version of timer_stats changes from v0.1 to v0.2

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] high-res timers: resume fix

Soeren Sonnenburg reported that upon resume he is getting
this backtrace:

[<c0119637>] smp_apic_timer_interrupt+0x57/0x90
[<c0142d30>] retrigger_next_event+0x0/0xb0
[<c0104d30>] apic_timer_interrupt+0x28/0x30
[<c0142d30>] retrigger_next_event+0x0/0xb0
[<c0140068>] __kfifo_put+0x8/0x90
[<c0130fe5>] on_each_cpu+0x35/0x60
[<c0143538>] clock_was_set+0x18/0x20
[<c0135cdc>] timekeeping_resume+0x7c/0xa0
[<c02aabe1>] __sysdev_resume+0x11/0x80
[<c02ab0c7>] sysdev_resume+0x47/0x80
[<c02b0b05>] device_power_up+0x5/0x10

it turns out that on resume we mistakenly re-enable interrupts too
early. Do the timer retrigger only on the current CPU.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Soeren Sonnenburg <kernel@nn7.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] hrtimers: hrtimer_clock_base description typo

The description for the hrtimer_clock_base struct describes "hrtimer_base".
That should be hrtimer_clock_base.

Signed-off-by: Andres Salomon <dilinger@debian.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] hrtimers: fix HRTIMER_CB_IRQSAFE_NO_SOFTIRQ description

The description for HRTIMER_CB_IRQSAFE_NO_SOFTIRQ is backwards; "NO
SOFTIRQ" sounds a whole lot like it means it must not be run in a softirq.

Signed-off-by: Andres Salomon <dilinger@debian.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] kernel-doc fixes for 2.6.20-git15 (non-drivers)

Fix kernel-doc warnings in 2.6.20-git15 (lib/, mm/, kernel/, include/).

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] Add SysRq-Q to print timer_list debug info

Add SysRq-Q to print pending timers and other timer info.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] Add debugging feature /proc/timer_stat

Add /proc/timer_stats support: debugging feature to profile timer expiration.
Both the starting site, process/PID and the expiration function is captured.
This allows the quick identification of timer event sources in a system.

Sample output:

# echo 1 > /proc/timer_stats
# cat /proc/timer_stats
Timer Stats Version: v0.1
Sample period: 4.010 s
24, 0 swapper hrtimer_stop_sched_tick (hrtimer_sched_tick)
11, 0 swapper sk_reset_timer (tcp_delack_timer)
6, 0 swapper hrtimer_stop_sched_tick (hrtimer_sched_tick)
2, 1 swapper queue_delayed_work_on (delayed_work_timer_fn)
17, 0 swapper hrtimer_restart_sched_tick (hrtimer_sched_tick)
2, 1 swapper queue_delayed_work_on (delayed_work_timer_fn)
4, 2050 pcscd do_nanosleep (hrtimer_wakeup)
5, 4179 sshd sk_reset_timer (tcp_write_timer)
4, 2248 yum-updatesd schedule_timeout (process_timeout)
18, 0 swapper hrtimer_restart_sched_tick (hrtimer_sched_tick)
3, 0 swapper sk_reset_timer (tcp_delack_timer)
1, 1 swapper neigh_table_init_no_netlink (neigh_periodic_timer)
2, 1 swapper e1000_up (e1000_watchdog)
1, 1 init schedule_timeout (process_timeout)
100 total events, 25.24 events/sec

[ cleanups and hrtimers support from Thomas Gleixner <tglx@linutronix.de> ]
[bunk@stusta.de: nr_entries can become static]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] hrtimers: add high resolution timer support

Implement high resolution timers on top of the hrtimers infrastructure and the
clockevents / tick-management framework. This provides accurate timers for
all hrtimer subsystem users.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] tick-management: dyntick / highres functionality

With Ingo Molnar <mingo@elte.hu>

Add functions to provide dynamic ticks and high resolution timers. The code
which keeps track of jiffies and handles the long idle periods is shared
between tick based and high resolution timer based dynticks. The dyntick
functionality can be disabled on the kernel commandline. Provide also the
infrastructure to support high resolution timers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] clockevents: add core functionality

Architectures register their clock event devices, in the clock events core.
Users of the clockevents core can get clock event devices for their use. The
clockevents core code provides notification mechanisms for various clock
related management events.

This allows to control the clock event devices without the architectures
having to worry about the details of function assignment. This is also a
preliminary for high resolution timers and dynamic ticks to allow the core
code to control the clock functionality without intrusive changes to the
architecture code.

[Fixes-by: Ingo Molnar <mingo@elte.hu>]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] hrtimers: clean up callback tracking

Reintroduce ktimers feature "optimized away" by the ktimers review process:
remove the curr_timer pointer from the cpu-base and use the hrtimer state.

No functional changes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] hrtimers; add state tracking

Reintroduce ktimers feature "optimized away" by the ktimers review process:
multiple hrtimer states to enable the running of hrtimers without holding the
cpu-base-lock.

(The "optimized" rbtree hack carried only 2 states worth of information and we
need 4 for high resolution timers and dynamic ticks.)

No functional changes.

Build-fixes-from: Andrew Morton <akpm@osdl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] hrtimers: cleanup locking

Improve kernel/hrtimers.c locking: use a per-CPU base with a lock to control
locking of all clocks belonging to a CPU. This simplifies code that needs to
lock all clocks at once. This makes life easier for high-res timers and
dyntick.

No functional changes.

[ optimization change from Andrew Morton <akpm@osdl.org> ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] hrtimers: namespace and enum cleanup

- hrtimers did not use the hrtimer_restart enum and relied on the implict
int representation. Fix the prototypes and the functions using the enums.
- Use seperate name spaces for the enumerations
- Convert hrtimer_restart macro to inline function
- Add comments

No functional changes.

[akpm@osdl.org: fix input driver]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] GTOD: persistent clock support

Persistent clock support: do proper timekeeping across suspend/resume.

[bunk@stusta.de: cleanup]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] posix-timers: Fix clock_nanosleep() doesn't return the remaining time in compatibility mode

The clock_nanosleep() function does not return the time remaining when the
sleep is interrupted by a signal.

This patch creates a new call out, compat_clock_nanosleep_restart(), which
handles returning the remaining time after a sleep is interrupted. This
patch revives clock_nanosleep_restart(). It is now accessed via the new
call out. The compat_clock_nanosleep_restart() is used for compatibility
access.

Since this is implemented in compatibility mode the normal path is
virtually unaffected - no real performance impact.

Signed-off-by: Toyo Abe <toyoa@mvista.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] Documentation for lock_key in struct hrtimer_base

Fixes an error message on make xmldocs.

Signed-off-by: Henrik Kretzschmar <henne@nachtwindheim.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] lockdep: annotate hrtimer base locks

Teach special (recursive) locking code to the lock validator. Has no effect
on non-lockdep kernels.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] ktime/hrtimer: fix kernel-doc comments

Fix kernel-doc formatting in ktime.h and hrtimer.[ch] files.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[RBTREE] Update hrtimers to use rb_parent() accessor macro.

Also switch it to use the same method of using off-tree nodes as
everyone else now does -- set them to point to themselves.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

Documentation: fix minor kernel-doc warnings

This patch updates the comments to match the actual code.

Signed-off-by: Martin Waitz <tali@admingilde.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

[PATCH] hrtimer: create generic sleeper

The removal of the data field in the hrtimer structure enforces the
embedding of the timer into another data structure. nanosleep now uses a
private implementation of the most common used timer callback function
(simple task wakeup).

In order to avoid the reimplentation of such functionality all over the
place a generic hrtimer_sleeper functionality is created.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] hrtimers: remove data field

The nanosleep cleanup allows to remove the data field of hrtimer. The
callback function can use container_of() to get it's own data. Since the
hrtimer structure is anyway embedded in other structures, this adds no
overhead.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] hrtimers: remove state field

Remove the state field and encode this information in the rb_node similiar to
normal timer.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] hrtimers: simplify nanosleep

nanosleep is the only user of the expired state, so let it manage this itself,
which makes the hrtimer code a bit simpler. The remaining time is also only
calculated if requested.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] hrtimers: pass current time to hrtimer_forward()

Pass current time to hrtimer_forward(). This allows to use the softirq time
in the timer base when the forward function is called from the timer callback.
Other places pass current time with a call to timer->base->get_time().

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] hrtimers: optimize softirq runqueues

The hrtimer softirq is called from the timer softirq every tick. Retrieve the
current time from xtime and wall_to_monotonic instead of calling
base->get_time() for each timer base. Store the time in the base structure
and provide a hook once clock source abstractions are in place and to keep the
code open for new base clocks.

Based on a patch from: Roman Zippel <zippel@linux-m68k.org>

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] fix next_timer_interrupt() for hrtimer

Also from Thomas Gleixner <tglx@linutronix.de>

Function next_timer_interrupt() got broken with a recent patch
6ba1b91213e81aa92b5cf7539f7d2a94ff54947c as sys_nanosleep() was moved to
hrtimer. This broke things as next_timer_interrupt() did not check hrtimer
tree for next event.

Function next_timer_interrupt() is needed with dyntick (CONFIG_NO_IDLE_HZ,
VST) implementations, as the system can be in idle when next hrtimer event
was supposed to happen. At least ARM and S390 currently use
next_timer_interrupt().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] hrtimers: cleanups and simplifications

Clean up the interface to hrtimers by changing the init code to pass the mode
as well as the clock. This allow the init code to select the correct base and
eliminates extra timer re-init code in posix-timers. We also simplify the
restart interface nanosleep use.

Signed-off-by: George Anzinger <george@mvista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] hrtimers: fix posix-timer requeue race

From: Steven Rostedtrostedt@goodmis.org <rostedt@goodmis.org>

CPU0 expires a posix-timer and runs the callback function. The signal is
queued.

After releasing the posix-timer lock and before returning to hrtimer_run_queue
CPU0 gets interrupted. CPU1 delivers the queued signal and rearms the timer.
CPU0 comes back to hrtimer_run_queue and sets the timer state to expired.

The next modification of the timer can result in an oops, because the state
information is wrong.

Keep track of state = RUNNING and check if the state has been in the return
path of hrtimer_run_queue. In case the state has been changed, ignore a
restart request and do not touch the state variable.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[hrtimer] Enforce resolution as lower limit of intervals

Roman Zippel pointed out that the missing lower limit of intervals
leads to an accounting error in the overrun count. Enforce the lower
limit of intervals to resolution in the timer forwarding code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

[hrtimer] Change resolution storage to ktime_t format

Change the storage format of the per base resolution to ktime_t to
make it easier accessible in the hrtimers code.

Change the resolution from (NSEC_PER_SEC/HZ) to TICK_NSEC as Roman
pointed out. TICK_NSEC is closer to the real resolution.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

[hrtimer] Remove listhead from hrtimer struct

The list_head in the hrtimer structure was introduced for easy access
to the first timer with the further extensions of real high resolution
timers in mind, but it turned out in the course of development that
it is not necessary for the standard use case. Remove the list head
and access the first expiry timer by a datafield in the timer base.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

[PATCH] hrtimer: convert posix timers completely

- convert posix-timers.c to use hrtimers

- remove the now obsolete abslist code

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] hrtimer: create hrtimer nanosleep API

introduce the hrtimer_nanosleep() and hrtimer_nanosleep_real() APIs. Not yet
used by any code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] hrtimer: hrtimer core code

hrtimer subsystem core. It is initialized at bootup and expired by the timer
interrupt, but is otherwise not utilized by any other subsystem yet.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>