- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Remove hacks to allow libkse to export its symbols in the LIBTHREAD_1_0
version namespace which was needed before the library version was
bumped.

WARNS=3'ify.

Repo copy libpthreads to libkse.
This introduces the WITHOUT_LIBKSE nob,
and changes WITHOUT_LIBPTHREADS to mean with neither threading libs.
Approved by: re(kensmith)

Enable symbol versioning by default. Use WITHOUT_SYMVER to disable it.
Warning, after symbol versioning is enabled, going back is not easy
(use WITHOUT_SYMVER at your own risk).

Change the default thread library to libthr.

There most likely still needs to be a version bump for at least the
thread libraries. If necessary, this will happen later.

Catch up with the renaming of the private version namespace.

Remove 3rd clause, renumber, ok per email

o Remove a cruft prevented libpthread sigaction(2) wrapper to
do its work for SIGINFO. Always install libpthread signal handler
wrapper for SIGINFO even if user SIG_IGN's or SIG_DFL's it.

SIGINFO has a special meaning for libpthread: when LIBPTHREAD_DEBUG
enviroment variable defined it is used for dumping an information
about threads to /tmp/.

Reported by: mi
Reviewed by: deischen
MFC after: 2 weeks

Bring libpthread up to WARNS level 2.

Reviewed by: deischen

Add compatibility symbol maps. libpthread (.so.1 and .so.2)
used LIBTHREAD_1_0 as its version definition, but now needs
to define its symbols in the same namespace used by libc.
The compatibility hooks allows you to use libraries and
binaries built and linked to libpthread before libc was
built with symbol versioning. The shims can be removed if
libpthread is given a version bump.

Reviewed by: davidxu

Only catch SIGINFO (for dumping thread states) when LIBPTHREAD_DEBUG
is defined in the environment.

Requested by: jmg & a few others

Fix off-by-one nanosecond in macro TIMESPEC_ADD.

Reviewed by: deischen
Approved by: re (dwhite)
MFC after : 4 days

Increase the default stacksizes:

32-bit 64-bit
main thread 2MB 4MB
other threads 1MB 2MB

Use a generic way to back threads out of wait queues when handling
signals instead of having more intricate knowledge of thread state
within signal handling.

Simplify signal code because of above (by David Xu).

Use macros for libpthread usage of pthread_cleanup_push() and
pthread_cleanup_pop(). This removes some instances of malloc()
and free() from the semaphore and pthread_once() implementations.

When single threaded and forking(), make sure that the current
thread's signal mask is inherited by the forked thread.

Use private mutexes for libc and libpthread. Signals are
deferred while threads hold private mutexes. This fix also
breaks www/linuxpluginwrapper; a patch that fixes it is at
http://people.freebsd.org/~deischen/kse/linuxpluginwrapper.diff

Fix race condition in condition variables where handling a
signal (pthread_kill() or kill()) may not see a wakeup
(pthread_cond_signal() or pthread_cond_broadcast()).

In collaboration with: davidxu

Save cancelflags in signal frame, this fixes a problem that
a thread in pthread_cond_wait handled a signal can no longer
be canceled.

Reviewed by: deischen

1. Move thread list flags into new separate member, and atomically
put DEAD thread on GC list, this closes a race between pthread_join
and thr_cleanup.
2. Introduce a mutex to protect tcb initialization, tls allocation and
deallocation code in rtld seems no lock protection or it is broken,
under stress testing, memory is corrupted.

Reviewed by: deischen
patch partly provided by: deischen

Add a way to force 1:1 mode for libpthread. To do this, define
LIBPTHREAD_SYSTEM_SCOPE in the environment.

You can still force libpthread to be built in strictly 1:1 by
adding -DSYSTEM_SCOPE_ONLY to CFLAGS. This is kept for archs
that don't yet support M:N mode.

Requested by: rwatson
Reviewed by: davidxu

s/TMDF_DONOTRUNUSER/TMDF_SUSPEND/g

Dicussed with: deischen

Don't include lock.h and pthread_md.h when we're being included by
libthread_db. Both headers are included seperately.

Add code to support thread debugging.
1. Add global varible _libkse_debug, debugger uses the varible to identify
libpthread. when the varible is written to non-zero by debugger, libpthread
will take some special action at context switch time, it will check
TMDF_DOTRUNUSER flags, if a thread has the flags set by debugger, it won't
be scheduled, when a thread leaves KSE critical region, thread checks
the flag, if it was set, the thread relinquish CPU.

2. Add pq_first_debug to select a thread allowd to run by debugger.

3. Some names prefixed with _thr are renamed to _thread prefix.

which is allowed to run by debugger.

Check pending signals, if there is signal will be unblocked by
sigsuspend, thread shouldn't wait, in old code, it may be
ignored.
When a signal handler is invoked in sigsuspend, thread gets
two different signal masks, one is in thread structure,
sigprocmask() can retrieve it, another is in ucontext
which is a third parameter of signal handler, the former is
the result of sigsuspend mask ORed with sigaction's sa_mask
and current signal, the later is the mask in thread structure
before sigsuspend is called. After signal handler is called,
the mask in ucontext should be copied into thread structure,
and becomes CURRENT signal mask, then sigsuspend returns to
user code.

Reviewed by: deischen
Tested by: Sean McNeil <sean@mcneil.com>

Provide a userland version of non-pshared semaphores and add cancellation
points to sem_wait() and sem_timedwait(). Also make sem_post signal-safe.

Add a simple work-around for deadlocking on recursive read locks
on a rwlock while there are writers waiting. We normally favor
writers but when a reader already has at least one other read lock,
we favor the reader. We don't track all the rwlocks owned by a
thread, nor all the threads that own a rwlock -- we just keep
a count of all the read locks owned by a thread.

PR: 24641

Forgot to commit this file for last commit. :(

Code clean up, remove unused MACROS and function prototypes.

Remove an unused struct definition.

Add cancellation points for accept() and connect().

Rename _thr_enter_cancellation_point to _thr_cancel_enter, rename
_thr_leave_cancellation_point to _thr_cancel_leave, add a parameter
to _thr_cancel_leave to indicate whether cancellation point should be
checked, this gives us an option to not check cancallation point if
a syscall successfully returns to avoid any leaks, current I have
creat(), open() and fcntl(F_DUPFD) to not check cancellation point
after they sucessfully returned.

Replace some members in structure kse with bit flags to same some
memory.

Conditionally compile THR_ASSERT to nothing if _PTHREAD_INVARIANTS is
not defined.

Inline some small functions in thr_cancel.c.

Use __predict_false in thr_kern.c for some executed only once code.

Reviewd by: deischen

1.Macro optimizing KSE_LOCK_ACQUIRE and THR_LOCK_ACQUIRE to use static fall
through branch predict as suggested in INTEL IA32 optimization guide.

2.Allocate siginfo arrary separately to avoid pthread to be allocated at
2K boundary, which hits L1 address alias problem and causes context
switch to be slow down.

3.Simplify context switch code by removing redundant code, code size is
reduced, so it is expected to run faster.

Reviewed by: deischen
Approved by: re (scottl)

Add an implementation for pthread_atfork().

Aside from the POSIX requirements for pthread_atfork(), when
fork()ing, take the malloc lock to keep malloc state consistent
in the child.

Reviewed by: davidxu

Complete cancellation support for M:N threads, check cancelling flag when
thread state is changed from RUNNING to WAIT state and do some cancellation
operations for every cancellable state.

Reviewed by: deischen

Save and restore timeout field for signal frame just like what we did
for interrupted field.
Also in _thr_sig_handler, retrieve current signal mask from kernel not
from ucp, the later is pre-unioned mask, not current signal mask.

1. Allocating and freeing lock related resource in _thr_alloc and _thr_free
to avoid potential memory leak, also fix a bug in pthread_create, contention
scope should be inherited when PTHREAD_INHERIT_SCHED is set, and also check
right field for PTHREAD_INHERIT_SCHED, scheduling inherit flag is in sched_inherit.
2. Execute hooks registered by atexit() on thread stack but not on scheduler
stack.
3. Simplify some code in _kse_single_thread by calling xxx_destroy functions.

Reviewed by: deischen

Original pthread_once code has memory leak if pthread_once_t is used in
a shared library or any other dyanmic allocated data block, once
pthread_once_t is initialized, a mutex is allocated, if we unload the
shared library or free those data block, then there is no way to deallocate
the mutex, result is memory leak.
To fix this problem, we don't use mutex field in pthread_once_t, instead,
we use its state field and an internal mutex and conditional variable in
libkse to do any synchronization, we introduce a third state IN_PROGRESS to
wait if another thread is already in invoking init_routine().
Also while I am here, make pthread_once() conformed to pthread cancellation
point specification.

Reviewed by: deischen

Add code to support pthread spin lock.

Reviewed by: deischen

Add code to support barrier synchronous object and implement
pthread_mutex_timedlock().

Reviewed by: deischen

Allow the concurrency level to be reduced.

Reviewed by: davidxu

Treat initial thread as scope system thread when KSE mode is not activated
yet, so we can protect some locking code from being interrupted by signal
handling. When KSE mode is turned on, reset the thread flag to scope process
except we are running in 1:1 mode which we needn't turn it off.
Also remove some unused member variables in structure kse.

Tested by: deischen

Rethink the MD interfaces for libpthread to account for
archs that can (or are required to) have per-thread registers.

Tested on i386, amd64; marcel is testing on ia64 and will
have some follow-up commits.

Reviewed by: davidxu

Simplify sigwait code a bit by using a waitset and removing oldsigmask.

Reviewed by: deischen

Move idle kse wakeup to outside of regions where locks are held.
This eliminates ping-ponging of locks, where the idle KSE wakes
up only to find the lock it needs is being held. This gives
little or no gain to M:N mode but greatly speeds up 1:1 mode.

Reviewed & Tested by: davidxu

Cleanup thread accounting. Don't reset a threads timeslice
when it blocks; it only gets reset when it yields.

Properly set a thread's default stack guardsize.

Reviewed by: davidxu

o Eliminate upcall for PTHREAD_SYSTEM_SCOPE thread, now it
is system bound thread and when it is blocked, no upcall is generated.

o Add ability to libkse to allow it run in pure 1:1 threading mode,
defining SYSTEM_SCOPE_ONLY in Makefile can turn on this option.

o Eliminate code for installing dummy signal handler for sigwait call.

o Add hash table to find thread.

Reviewed by: deischen

o Use a daemon thread to monitor signal events in kernel, if pending
signals were changed in kernel, it will retrieve the pending set and
try to find a thread to dispatch the signal. The dispatching process
can be rolled back if the signal is no longer in kernel.

o Create two functions _thr_signal_init() and _thr_signal_deinit(),
all signal action settings are retrieved from kernel when threading
mode is turned on, after a fork(), child process will reset them to
user settings by calling _thr_signal_deinit(). when threading mode
is not turned on, all signal operations are direct past to kernel.

o When a thread generated a synchoronous signals and its context returned
from completed list, UTS will retrieve the signal from its mailbox and try
to deliver the signal to thread.

o Context signal mask is now only used when delivering signals, thread's
current signal mask is always the one in pthread structure.

o Remove have_signals field in pthread structure, replace it with
psf_valid in pthread_signal_frame. when psf_valid is true, in context
switch time, thread will backout itself from some mutex/condition
internal queues, then begin to process signals. when a thread is not
at blocked state and running, check_pending indicates there are signals
for the thread, after preempted and then resumed time, UTS will try to
deliver signals to the thread.

o At signal delivering time, not only pending signals in thread will be
scanned, process's pending signals will be scanned too.

o Change sigwait code a bit, remove field sigwait in pthread_wait_data,
replace it with oldsigmask in pthread structure, when a thread calls
sigwait(), its current signal mask is backuped to oldsigmask, and waitset
is copied to its signal mask and when the thread gets a signal in the
waitset range, its current signal mask is restored from oldsigmask,
these are done in atomic fashion.

o Two additional POSIX APIs are implemented, sigwaitinfo() and sigtimedwait().

o Signal code locking is better than previous, there is fewer race conditions.

o Temporary disable most of code in _kse_single_thread as it is not safe
after fork().

Untangle the inter-dependency of kse types and ksd types/functions
by moving the definition of struct ksd to pthread_md.h and removing
the inclusion of ksd.h from thr_private.h (which has the definition
of struct kse and kse_critical_t). This allows ksd.h to have inline
functions that use struct kse and kse_critical_t and generally
yields a cleaner implementation at the cost of not having all ksd
related types/definitions in one header.

Implement the ksd functionality on ia64 by using inline functions
and permanently remove ksd.c from the ia64 specific makefile.

This change does not clean up the i386 specific version of ksd.h.

NOTE: The ksd code on ia64 abuses the tp register in the same way
as it is abused in libthr in that it is incompatible with the
runtime specification. This will be address when support for TLS
hits the tree.

Attempt to eliminate PLT relocations from rwlock aquire/release
path, making them suitable for direct use by the dynamic loader.

Register libpthread-specific locking API with rtld on startup.

This still has some rough edges with signals which should be
addresses later.

Approved by: re (scottl)

Don't really spin on a spinlock; silently convert it to the same
low-level lock used by the libpthread implementation. In the
future, we'll eliminate spinlocks from libc but that will wait
until after 5.1-release.

Don't call an application signal handler if the handler is
the same as the library-installed handler. This seems to
be possible after a fork and is the cause of konsole hangs.

Approved by: re@ (jhb)

Add a method of yielding the current thread with the scheduler
lock held (_thr_sched_switch_unlocked()) and use this to avoid
dropping the scheduler lock and having the scheduler retake the
same lock again.

Add a better way of detecting if a low-level lock is in use.

When switching out a thread due to blocking in the UTS, don't
switch to the KSE's scheduler stack only to switch back to
another thread. If possible switch to the new thread directly
from the old thread and avoid the overhead of the extra
context switch.

Check for pending signals on a thread when entering the scheduler
and add them to the threads signal frame. This includes some
other minor signal fixes.

Most of this was a joint effor between davidxu and myself.

Reviewed by: davidxu
Approved by: re@ (blanket for libpthread)

Fix suspend and resume.

Submitted (in part) by: Kazuaki Oda <kaakun@highway.ne.jp>

Move the mailbox to the beginning of the thread and align the
thread so that the context (SSE FPU state) is also aligned.

o Don't add a scope system thread's KSE to the list of available
KSEs when it's thread exits; allow the GC handler to do that.

o Make spinlock/spinlock critical regions.

The following were submitted by davidxu

o Alow thr_switch() to take a null mailbox argument.

o Better protect cancellation checks.

o Don't set KSE specific data when creating new KSEs; rely on the
first upcall of the KSE to set it.

o Add the ability to set the maximum concurrency level and do this
automatically. We should have a way to enable/disable this with
some sort of tunable because some applications may not want this
to be the default.

o Hold the scheduling lock across thread switch calls.

o If scheduling of a thread fails, make sure to remove it from the list
of active threads.

o Better protect accesses to a joining threads when the target thread is
exited and detached.

o Remove some macro definitions that are now provided by <sys/kse.h>.

o Don't leave the library in threaded mode if creation of the initial
KSE fails.

o Wakeup idle KSEs when there are threads ready to run.

o Maintain the number of threads active in the priority queue.

Protect thread errno from being changed while operating
on behalf of the KSE.

Add a kse_reinit function to reinitialize a reused KSE.

Submitted by: davidxu

Add a couple asserts to pthread_cond_foo to ensure the (low-level)
lock level is 0. Thus far, the threads implementation doesn't use
mutexes or condition variables so the lock level should be 0.

Save the return value when trying to schedule a new thread and
use this to return an error from pthread_create().

Change the max sleep time for an idle KSE to 1 minute from 2 minutes.

Maintain a count of the number of KSEs within a KSEG.

With these changes scope system threads seem to work, but heavy
use of them crash the kernel (supposedly VM bugs).

Add an i386-specifc hack to always set %gs. There still seems
to be instances where the kernel doesn't properly save and/or
restore it.

Use noupcall and nocompleted flags in the KSE mailbox. These
require kernel changes to work which will be committed sometime
later. Things still work without the changes.

Remove the general kse entry function and use two different
functions -- one for scope system threads and one for scope
process threads. The scope system function is not yet enabled
and we use the same function for all threads at the moment.

Keep a copy of the KSE stack for the case that a KSE runs
a scope system thread and uses the same stack as the thread
(no upcalls are generated, so a separate stack isn't needed).
This isn't enabled yet.

Use a separate field for the KSE waiting flag. It isn't
correct to use the mailbox flags field.

The following fixes were provided by David Xu:

o Initialize condition variable locks with thread versions
of the low-level locking functions instead of the kse versions.

o Enable threading before creating the first thread instead
of after.

o Don't enter critical regions when trying to malloc/free
or call functions that malloc/free.

o Take the scheduling lock when inheriting thread attributes.

o Check the attribute's stack pointer instead of the
attributes stack size for null when allocating a
thread's stack.

o Add a kseg reinit function so we don't have to destroy and
then recreate the same lock.

o Check the return value of kse_create() and return an
appropriate error if it fails.

o Don't forget to destroy a thread's locks when freeing it.

o Examine the correct flags word for checking to see if
a thread is in a synchronization queue.

Things should now work on an SMP kernel.

Sorry folks; I accidentally committed a patch from what I was working
on a couple of days ago. This should be the most recent changes.

Noticed by: davidxu

Revamp libpthread so that it has a chance of working in an SMP
environment. This includes support for multiple KSEs and KSEGs.

The ability to create more than 1 KSE via pthread_setconcurrency()
is in the works as well as support for PTHREAD_SCOPE_SYSTEM threads.
Those should come shortly.

There are still some known issues which davidxu and I are working
on, but it'll make it easier for us by committing what we have.

This library now passes all of the ACE tests that libc_r passes
with the exception of one. It also seems to work OK with KDE
including konqueror, kwrite, etc. I haven't been able to get
mozilla to run due to lack of java plugin, so I'd be interested
to see how it works with that.

Reviewed by: davidxu

Deliver signals posted via an upcall to the appropriate thread.

Schedule an idle context to block until timeouts expire without blocking
further upcalls.

Use KSE to schedule threads.

Make libpthread KSE aware.

Reviewed by: deischen, julian
Approved by: -arch

Make the changes needed for libpthread to compile in its new home.
The new libpthread will provide POSIX threading support using KSE.
These files were previously repo-copied from src/lib/libc_r.

Reviewed by: deischen
Approved by: -arch

Remove much of the dereferencing of the fd table entries to look
at file flags and replace it with functions that will avoid null
pointer checks.

MFC to be done by archie ;-)

PR: 42100
Reviewed by: archie, robert
MFC after: 3 days

Missed in earlier commit -- I did cvs commit src/lib/libc. Oops.

Revamp suspend and resume. While I'm here add pthread_suspend_all_np()
and pthread_resume_all_np(). These suspend and resume all threads except
the current thread, respectively. The existing functions pthread_single_np()
and pthread_multi_np(), which formerly had no effect, now exhibit the same
behaviour and pthread_suspend_all_np() and pthread_resume_all_np(). These
functions have been added mostly for the native java port.

Don't allow the uthread kernel pipe to use the same descriptors as
stdio. Mostily submitted by Oswald Buddenhagen <ossi@kde.org>.

Correct some minor style nits.

Undo namespace pollution by prefixing the globals pthread_guard_default and
pthread_page_size.

Fix a bunch line wrapping.

Pointed out by: deischen

Don't use PAGE_SIZE in userland, instead use getpagesize(), this is to
allow running on other arches when the instructions are supported but
the page size granularity is not.

Glanced at by: peter

Add the ability to recognize old references to keys, and return NULL
when old keys are referenced (after pthread_key_delete()) via
pthread_getspecific().

Don't rely on <sys/signal.h> to include <sys/ucontext.h>

This has been sitting in my local tree long enough. Remove the use
of an alternate signal stack for handling signals. Let the kernel
send signals on the stack of the current thread and teach the threads
signal handler how to deliver signals to the current thread if it
needs to. Also, always store a threads context as a jmp_buf. Eventually
this will change to be a ucontext_t or mcontext_t.

Other small nits. Use struct pthread * instead of pthread_t in internal
library routines. The threads code wants struct pthread *, and pthread_t
doesn't necessarily have to be the same.

Reviewed by: jasone

Use the real function address (instead of function address + 8) for the
return address when modifying a jmp_buf to create a new thread context.
Also set t12 with the return address.

This should fix libc_r on alpha.

With much detective work by: Bernd Walter <ticso@cicely.de>

Fix pthread_join so that it works if the target thread exits while
the joining thread is in a signal handler.

Reported by: Loren James Rittle <rittle@labs.mot.com>
MFC after: 1 week

Make libc_r check the kern.usrstack sysctl instead of using internal
kernel #defines to figure out where the stack is located. This stops
libc_r from exploding when the kernel is compiled with a different
KVM size. IMHO this is all kinda bogus, it would be better to just
check %esp and work from that.

Style: sort __sys_foo() prototypes, tabs -> spaces, etc.

Removed:

- uthread_signal.c; libc_r does not wrap signal() since 1998/04/29.

- uthread_attr_setprio.c; it was never connected to the build, and
pthread_attr_setprio() does not exist in POSIX.

- uthread_sigblock.c and uthread_sigsetmask.c; these were no-ops
bloating libc_r's space.

pthread_private.h:

- Removed prototypes of non-syscalls: send().

- Removed prototypes of unused syscalls: sigpending(), sigsuspend(),
and select().

- Fixed prototype of fork().

- MFS: Fixed prototypes of <sys/socket.h> syscalls.

Reviewed by: deischen
Approved by: deischen, jasone

Fix a bug in canceling joining threads.
Do not detach canceled threads.

Reported by: Arno Klaassen <arno@heho.snv.jussieu.fr>
Collaboration with: deischen

Implement pthread_attr_[gs]etguardsize(). Non-default-size stacks used to
be malloc()ed, but they are now allocated using mmap(), just as the
default-size stacks are. A separate cache of stacks is kept for
non-default-size stacks.

Collaboration with: deischen

Fix a race condition in pthread_join(). All of the following must occur
atomically:

1) Search _thread_list for the thread to join.
2) Search _dead_list for the thread to join.
3) Set the running thread as the joiner.

While we're at it, fix a race in the case where multiple threads try to
join on the same thread. POSIX says that the behavior of multiple joiners
is undefined, but the fix is cheap as a result of the other fix.

Instead of using a join queue for each thread, use a single pointer to
keep track of a joiner. POSIX only supports a single joiner, so this
simplification is acceptable.

At the same time, make sure to mark a joined thread as detached so that
its resources can be freed.

Reviewed by: deischen
PR: 24345

Add thread safety wrappers for the posix1e syscalls that deal with file
descriptors.

Approved by: rwatson
Obtained from: TrustedBSD Project

Limit threads clock resolution to no less than 1000usec (1000Hz).

PR: 25300
Submitted by: Tom Pavel <pavel@alum.mit.edu> (in part)

Remove (int) file descriptor locking. It should be up to the
application to provide locking for I/O operations. This doesn't
break any of my tests, but the old behavior can be restored by
compiling with _FDLOCKS_ENABLED. This will eventually be removed
when it is obvious it does not cause any problems.

Remove most of flockfile implementation, with the exception of
flockfile_debug.

Make error messages more informational (submitted by Mike Heffner
<spock@techfour.net>, who's now known as mikeh@FreeBSD.org).

s/_thread_sys_write/__sys_write/

Submitted by: Mike Heffner <mheffner@vt.edu>

Unbreak world by correctly specifying the prototype for __sys_aio_suspend.
A make buildworld was done but not with the committed pthread_private.h.

Reported by: Manfred Antar <null@pozo.com>

_exit in libc is now __sys_exit not __sys__exit.

Add another check for thread library initialization (jdp, we
really need a way to get _thread_init called at program start
before any constructors are run).

Add weak definitions for wrapped system calls. In general:

_foo - wrapped system call
foo - weak definition to _foo

and for cancellation points:

_foo - wrapped system call
__foo - enter cancellation point, call _foo(), leave
cancellation point
foo - weak definition to __foo

Change use of global _thread_run to call a function to get the
currently running thread.

Make all pthread_foo functions weak definitions to _pthread_foo,
where _pthread_foo is the implementation. This allows an application
to provide its own pthread functions.

Provide slightly different versions of pthread_mutex_lock and
pthread_mutex_init so that we can tell the difference between
a libc mutex and an application mutex. Threads holding mutexes
internal to libc should never be allowed to exit, call signal
handlers, or cancel.

Approved by: -arch

Fix MD macros to work for alpha. Without this fix, threads under alpha
seem to be totally broke.

MFC Candidate

Submitted by: gallatin

When entering the scheduler from the signal handler, tell
the kernel to (re)use the alternate signal stack. In this
case, we don't return normally from the signal handler,
so the kernel still thinks we are using the signal stack.
The fixes a nasty bug where the signal handler can start
fiddling with the stack of a thread while the handler is
actually running on the same stack.

MFC candidate

Don't needlessly poll file descriptors when there are no
file descriptors needing to be polled (Doh!). Reported
by Dan Nelson <dnelson@emsphone.com>.

Don't install and start the scheduling timer until the
first thread is created. This prevents the overhead of
having a periodic scheduling signal in a single threaded
program. Reported by Dan Nelson <dnelson@emsphone.com>.

Allow builtin longjmps out of application installed
signal handlers without the need perform any post-handler
cleanup:

o Change signal handling to save the threads interrupted
context on the stack. The threads current context is
now always stored in the same place (in the pthread).
If and when a signal handler returns, the interrupted
context is copied back to the storage area in the pthread.

o Before calling invoking a signal handler for a thread,
back the thread out of any internal waiting queues
(mutex, CV, join, etc) to which it belongs.

Rework uthread_info.c a bit to make it easier to change
the format of a thread dump.

Use an alternal signal stack for the thread library's
signal handler. This allows us to fiddle with the main
threads stack without fear of it being in use.

Reviewed by: jasone

Try and get libc_r to compile again on the alpha after deischen's commit

Implement zero system call thread switching. Performance of
thread switches should be on par with that under scheduler
activations.

o Timing is achieved through the use of a fixed interval
timer (ITIMER_PROF) to count scheduling ticks instead
of retrieving the time-of-day upon every thread switch
and calculating elapsed real time.

o Polling for I/O readiness is performed once for each
scheduling tick instead of every thread switch.

o The non-signal saving/restoring versions of setjmp/longjmp
are used to save and restore thread contexts. This may
allow the removal of _THREAD_SAFE macros from setjmp()
and longjmp() - needs more investigation.

Change signal handling so that signals are handled in the
context of the thread that is receiving the signal. When
signals are dispatched to a thread, a special signal handling
frame is created on top of the target threads stack. The
frame contains the threads saved state information and a new
context in which the thread can run. The applications signal
handler is invoked through a wrapper routine that knows how
to restore the threads saved state and unwind to previous
frames.

Fix interruption of threads due to signals. Some states
were being improperly interrupted while other states were
not being interrupted. This should fix several PRs.

Signal handlers, which are invoked as a result of a process
signal (not by pthread_kill()), are now called with the
code (or siginfo_t if SA_SIGINFO was set in sa_flags) and
sigcontext_t as received from the process signal handler.

Modify the search for a thread to which a signal is delivered.
The search algorithm is now:

o First thread found in sigwait() with signal in wait mask.
o First thread found sigsuspend()'d on the signal.
o Current thread if signal is unmasked.
o First thread found with signal unmasked.

Collapse machine dependent support into macros defined in
pthread_private.h. These should probably eventually be moved
into separate MD files.

Change the range of settable priorities to be compliant with
POSIX (0-31). The threads library uses higher priorities
internally for real-time threads (not yet implemented) and
threads executing signal handlers. Real-time threads and
threads running signal handlers add 64 and 32, respectively,
to a threads base priority.

Some other small changes and cleanups.

PR: 17757 18559 21943
Reviewed by: jasone

Add thread-safe wrapper for fpathconf(2) syscall.

Reviewed by: jlemon

Add wrapper for kevent() syscall

Noted as missing by: nicolas.leonard@animaths.com

If multiple threads are blocked in sigwait() for the same signal that does
not have a user-supplied signal handler, when a signal is delivered, one
thread will receive the signal, and then the code reverts to having no
signal handler for the signal. This can leave the other sigwait()ing
threads stranded permanently if the signal is later ignored, or can result
in process termination when the process should have delivered the signal to
one of the threads in sigwait().

To fix this problem, maintain a count of sigwait()ers for each signal that
has no default signal handler. Use the count to correctly install/uninstall
dummy signal handlers.

Reviewed by: deischen

pthread_mutex_lock(), pthread_cond_trywait(), and pthread_cond_wait() are
not allowed to return EINTR, but use of pthread_suspend_np() could cause
EINTR to be returned. To fix this, restructure pthread_suspend_np() so that
it does not interrupt a thread that is waiting on a mutex or condition, and
keep enough state around that pthread_resume_np() can fix things up
afterwards.

Reviewed by: deischen

Back out the previous change to the queue(3) interface.
It was not discussed and should probably not happen.

Requested by: msmith and others

Change the way that the queue(3) structures are declared; don't assume that
the type argument to *_HEAD and *_ENTRY is a struct.

Suggested by: phk
Reviewed by: phk
Approved by: mdodd

Explicitly include sys/cdefs.h to get the definition of __strong_reference(),
rather than getting lucky due to header dependencies.

Fix pthread_suspend_np/pthread_resume_np. For the record, suspending a
thread waiting on an event (I/O, condvar, etc) will, when resumed using
pthread_resume_np, return with EINTR. For example, suspending and resuming
a thread blocked on read() will not requeue the thread for the read, but
will return -1 with errno = EINTR. If the suspended thread is in a critical
region, the thread is suspended as soon as it leaves the critical region.

Fix a bogon in pthread_kill() where a signal was being delivered twice
to threads waiting in sigwait().

Reported by (suspend/resume bug): jdp
Reviewed by: jasone

Minor *jmp() cleanups.

Add sem_*() functions. Named semaphores and process-shared semaphores
are not supported by this implementation, and the error return values
from sem_init(), sem_open(), sem_close(), and sem_unlink() reflect this.

Approved by: jkh

Do signal deferral for pthread_kill() as it was done in the old days.

Submitted by: deischen

Implement continuations to correctly handle [sig|_]longjmp() inside of a
signal handler. Explicitly check for jumps to anywhere other than the
current stack, since such jumps are undefined according to POSIX.

While we're at it, convert thread cancellation to use continuations, since
it's cleaner than the original cancellation code.

Avoid delivering a signal to a thread twice. This was a pre-existing bug,
but was likely unexposed until these other changes were made.

Defer signals generated by pthread_kill() so that they can be delivered on
the appropriate stack. deischen claims that this is unnecessary, which is
likely true, but without this change, pthread_kill() can cause undefined
priority queue states and/or PANICs in [sig|_]longjmp(), so I'm leaving
this in for now. To compile this code out and exercise the bug, define
the _NO_UNDISPATCH cpp macro. Defining _PTHREADS_INVARIANTS as well will
cause earlier crashes.

PR: kern/14685
Collaboration with: deischen

Don't explicitly mmap() red zones at the bottom of thread stacks (except
the initial thread). Instead, just leave an unmapped gap between thread
stacks and make sure that the thread stacks won't grow into these gaps,
simply by limiting the size of the stacks with the 'len' argument to
mmap(). This (if I understand correctly) reduces VM overhead
considerably.

Reviewed by: deischen

Fixes for signal handling:

o Don't call signal handlers with the signal handler access lock
held.
o Remove pending signals before calling signal handlers. If
pending signals were not removed prior to handling them,
invocation of the handler could cause the handler to be
called more than once for the same signal. Found by: JB
o When SIGCHLD arrives, wake up all threads in PS_WAIT_WAIT
(wait4).

PR: bin/15328
Reviewed by: jasone

Change signal handling to conform to POSIX specified semantics.
Before this change, a signal was delivered to each thread that
didn't have the signal masked. Signals also improperly woke up
threads waiting on I/O. With this change, signals are now
handled in the following way:

o If a thread is waiting in a sigwait for the signal,
then the thread is woken up.

o If no threads are sigwait'ing on the signal and a
thread is in a sigsuspend waiting for the signal,
then the thread is woken up.

o In the case that no threads are waiting or suspended
on the signal, then the signal is delivered to the
first thread we find that has the signal unmasked.

o If no threads are waiting or suspended on the signal,
and no threads have the signal unmasked, then the signal
is added to the process wide pending signal set. The
signal will be delivered to the first thread that unmasks
the signal.

If there is an installed signal handler, it is only invoked
if the chosen thread was not in a sigwait.

In the case that multiple threads are waiting or suspended
on a signal, or multiple threads have the signal unmasked,
we wake up/deliver the signal to the first thread we find.
The above rules still apply.

Reported by: Scott Hess <scott@avantgo.com>
Reviewed by: jb, jasone

* Fix the stack allocation code so that it works for alpha. Change it
to use mmap(..., MAP_STACK, ...) on alpha too since that should work
now.
* Add hooks to allow GDB to access the internals of pthreads without
having to know the exact layout of struct pthread.

Reviewed by: deischen

add pthread_cancel, obtained from OpenBSD.

eischen (Daniel Eischen) added wrappers to protect against cancled
threads orphaning internal resources.

the cancelability code is still a bit fuzzy but works for test
programs of my own, OpenBSD's and some examples from ORA's books.

add readdir_r to both libc and libc_r

add some 'const' attributes to function parameters

Reviewed by: eischen, jasone

sigset_t change (part 5 of 5)
-----------------------------

Most of the userland changes are in libc. For both the alpha
and the i386 setjmp has been changed to accomodate for the
new sigset_t. Internally, libc is mostly rewritten to use the
new syscalls. The exception is in compat-43/sigcompat.c

The POSIX thread library has also been rewritten to use the
new sigset_t. Except, that it currently only handles NSIG
signals instead of the maximum _SIG_MAXSIG. This should not
be a problem because current applications don't use any
signals higher than NSIG.

There are version bumps for the following libraries:
libdialog
libreadline
libc
libc_r
libedit
libftpio
libss

These libraries either a) have one of the modified structures
visible in the interface, or b) use sigset_t internally and
may cause breakage if new binaries are used against libraries
that don't have the sigset_t change. This not an immediate
issue, but will be as soon as applications start using the
new range to its fullest.

NOTE: libncurses already had an version bump and has not been
given one now.

NOTE: doscmd is a real casualty and has been disconnected for
the moment. Reconnection will eventually happen after
doscmd has been fixed. I'm aware that being the last one
to touch it, I'm automaticly promoted to being maintainer.
According to good taste this means that I will receive a
badge which either will be glued or mechanically stapled,
drilled or otherwise violently forced onto me :-)

NOTE: pcvt/vttest cannot be compiled with -traditional. The
change cause sys/types to be included along the way which
contains the const and volatile modifiers. I don't consider
this a solution, but more a workaround.

$Id$ -> $FreeBSD$

Fix thread initialization to allow for the case where stdio file
descriptors are not opened.

PR: bin/12853
Reviewed by: jb

Use USRSTACK (defined in <machine/vmparam.h>) to get top of the initial stack.
PTHREAD_STACK_TOP was wrong for all supported architectures.

Modify previous changes to conform better to libc_r's coding style.

Always use mmap() for default-size stack allocation. Use MAP_ANON instead
of MAP_STACK on the alpha architecture.

Reduce the amount of code executed while owning _gc_mutex during stack
allocation.

Always use growable thread stacks on the i386. The VM_STACK kernel option
must be made default for the alpha before growable thread stacks are
enabled for the alpha.

Use growable stacks for thread stacks that are the default stack size.

Cache discarded default thread stacks for use in subsequent thread creations.

Create a red zone at the end of each stack (including the initial thread
stack), with the hope of causing a segfault if a stack overflows.

To activate these modifications, add -D_PTHREAD_GSTACK to CFLAGS in
src/lib/libc_r/Makefile. Since the modifications depend on the VM_STACK
kernel option, I'm not sure how to safely use growable stacks by default.

Testing, as well as algorithmic and stylistic comments are welcome.

In the words of the author:

o The polling mechanism for I/O readiness was changed from
select() to poll(). In additon, a wrapped version of poll()
is now provided.

o The wrapped select routine now converts each fd_set to a
poll array so that the thread scheduler doesn't have to
perform a bitwise search for selected fds each time file
descriptors are polled for I/O readiness.

o The thread scheduler was modified to use a new queue (_workq)
for threads that need work. Threads waiting for I/O readiness
and spinblocks are added to the work queue in addition to the
waiting queue. This reduces the time spent forming/searching
the array of file descriptors being polled.

o The waiting queue (_waitingq) is now maintained in order of
thread wakeup time. This allows the thread scheduler to
find the nearest wakeup time by looking at the first thread
in the queue instead of searching the entire queue.

o Removed file descriptor locking for select/poll routines. An
application should not rely on the threads library for providing
this locking; if necessary, the application should use mutexes
to protect selecting/polling of file descriptors.

o Retrieve and use the kernel clock rate/resolution at startup
instead of hardcoding the clock resolution to 10 msec (tested
with kernel running at 1000 HZ).

o All queues have been changed to use queue.h macros. These
include the queues of all threads, dead threads, and threads
waiting for file descriptor locks.

o Added reinitialization of the GC mutex and condition variable
after a fork. Also prevented reallocation of the ready queue
after a fork.

o Prevented the wrapped close routine from closing the thread
kernel pipes.

o Initialized file descriptor table for stdio entries at thread
init.

o Provided additional flags to indicate to what queues threads
belong.

o Moved TAILQ initialization for statically allocated mutex and
condition variables to after the spinlock.

o Added dispatching of signals to pthread_kill. Removing the
dispatching of signals from thread activation broke sigsuspend
when pthread_kill was used to send a signal to a thread.

o Temporarily set the state of a thread to PS_SUSPENDED when it
is first created and placed in the list of threads so that it
will not be accidentally scheduled before becoming a member
of one of the scheduling queues.

o Change the signal handler to queue signals to the thread kernel
pipe if the scheduling queues are protected. When scheduling
queues are unprotected, signals are then dequeued and handled.

o Ensured that all installed signal handlers block the scheduling
signal and that the scheduling signal handler blocks all
other signals. This ensures that the signal handler is only
interruptible for and by non-scheduling signals. An atomic
lock is used to decide which instance of the signal handler
will handle pending signals.

o Removed _lock_thread_list and _unlock_thread_list as they are
no longer used to protect the thread list.

o Added missing RCS IDs to modified files.

o Added checks for appropriate queue membership and activity when
adding, removing, and searching the scheduling queues. These
checks add very little overhead and are enabled when compiled
with _PTHREADS_INVARIANTS defined. Suggested and implemented
by Tor Egge with some modification by me.

o Close a race condition in uthread_close. (Tor Egge)

o Protect the scheduling queues while modifying them in
pthread_cond_signal and _thread_fd_unlock. (Tor Egge)

o Ensure that when a thread gets a mutex, the mutex is on that
threads list of owned mutexes. (Tor Egge)

o Set the kernel-in-scheduler flag in _thread_kern_sched_state
and _thread_kern_sched_state_unlock to prevent a scheduling
signal from calling the scheduler again. (Tor Egge)

o Don't use TAILQ_FOREACH macro while searching the waiting
queue for threads in a sigwait state, because a change of
state destroys the TAILQ link. It is actually safe to do
so, though, because once a sigwaiting thread is found, the
loop ends and the function returns. (Tor Egge)

o When dispatching signals to threads, make the thread inherit
the signal deferral flag of the currently running thread.
(Tor Egge)

Submitted by: Daniel Eischen <eischen@vigrid.com> and
Tor Egge <Tor.Egge@fast.no>

Added a missing comma to the static condition variable initialisation
definition.

Submitted by: David Leonard <David.Leonard@csee.uq.edu.au>, an OpenBSD guy.

Fix a problem with static initialisation of mutexes and condition
variables.

Submitted by: Dan Eischen <eischen@vigrid.com>

[ The author's description... ]

o Runnable threads are now maintained in priority queues. The
implementation requires two things:

1.) The priority queues must be protected during insertion
and removal of threads. Since the kernel scheduler
must modify the priority queues, a spinlock for
protection cannot be used. The functions
_thread_kern_sched_defer() and _thread_kern_sched_undefer()
were added to {un}defer kernel scheduler activation.

2.) A thread (active) priority change can be performed only
when the thread is removed from the priority queue. The
implementation uses a threads active priority when
inserting it into the queue.

A by-product is that thread switches are much faster. A
separate queue is used for waiting and/or blocked threads,
and it is searched at most 2 times in the kernel scheduler
when there are active threads. It should be possible to
reduce this to once by combining polling of threads waiting
on I/O with the loop that looks for timed out threads and
the minimum timeout value.

o Functions to defer kernel scheduler activation were added. These
are _thread_kern_sched_defer() and _thread_kern_sched_undefer()
and may be called recursively. These routines do not block the
scheduling signal, but latch its occurrence. The signal handler
will not call the kernel scheduler when the running thread has
deferred scheduling, but it will be called when running thread
undefers scheduling.

o Added support for _POSIX_THREAD_PRIORITY_SCHEDULING. All the
POSIX routines required by this should now be implemented.
One note, SCHED_OTHER, SCHED_FIFO, and SCHED_RR are required
to be defined by including pthread.h. These defines are currently
in sched.h. I modified pthread.h to include sched.h but don't
know if this is the proper thing to do.

o Added support for priority protection and inheritence mutexes.
This allows definition of _POSIX_THREAD_PRIO_PROTECT and
_POSIX_THREAD_PRIO_INHERIT.

o Added additional error checks required by POSIX for mutexes and
condition variables.

o Provided a wrapper for sigpending which is marked as a hidden
syscall.

o Added a non-portable function as a debugging aid to allow an
application to monitor thread context switches. An application
can install a routine that gets called everytime a thread
(explicitly created by the application) gets context switched.
The routine gets passed the pthread IDs of the threads that are
being switched in and out.

Submitted by: Dan Eischen <eischen@vigrid.com>

Changes by me:

o Added a PS_SPINBLOCK state to deal with the priority inversion
problem most often (I think) seen by threads calling malloc/free/realloc.

o Dispatch signals to the running thread directly rather than at a
context switch to avoid the situation where the switch never occurs.

Increase the size of private thread flags so that the test for a
thread trying to call pthread_exit() from a cleanup handler actually
works.

Submitted by: David Leonard <david.leonard@csee.uq.edu.au> OpenBSD

Close a window between unlocking a spinlock and changing the thread state.

- Fix the debug macros.
- Add support of a thread being listed in the dead thread list as well
as the thread list.
- Add a new thread state to make sigwait work properly. (Submitted by
Daniel M. Eischen <eischen@vigrid.com>)
- Add global variable for the garbage collector mutex and condition
variable.
- Delete a couple of prototypes that are no longer required.
- Add a prototype for the garbage collector thread.

Implement pthread read/write locks as defined by Version 2 of the Single
UNIX Specification.

As with our standard mutexes, process shared locks are not supported at
this time.

Add compile time thread lock debug support.

Add a thread specific flag to trap the case where pthread_exit() is
called from a destructor in violation of the Posix standard.

Re-design the thread specific key structure.

Change signal model to match POSIX (i.e. one set of signal handlers
for the process, not a separate set for each thread). By default, the
process now only has signal handlers installed for SIGVTALRM, SIGINFO
and SIGCHLD. The thread kernel signal handler is installed for other
signals on demand. This means that SIG_IGN and SIG_DFL processing is now
left to the kernel, not the thread kernel.

Change the signal dispatch to no longer use a signal thread, and
call the signal handler using the stack of the thread that has the
signal pending.

Change the atomic lock method to use test-and-set asm code with
a yield if blocked. This introduces separate locks for each type
of object instead of blocking signals to prevent a context
switch. It was this blocking of signals that caused the performance
degradation the people have noted.

This is a *big* change!

Change the FILE locking to be by FILE, not by the underlying fd as
it was. Add a FILE_WAIT state and queue threads waiting for a FILE
lock. Start using the sys/queue.h macros instead of the way that MIT
pthreads did it.

Add a thread name to the private thread structure and a non-POSIX
function to set this. This helps (me at least) when sending a SIGINFO
to a threaded process to get a /tmp/uthread.dump to see what the
<expletive deleted> threads are doing this time. It is nice to be
able to recognise (yes, I spell that with an 's' too) which threads
are which.

Rename static initializer defines for opaque structures so that the
POSIX specified names can be declared in pthread.h.

Add a magic field to the pthread structure to help recognize valid
threads from invalid ones. The pthread structure is opaque to the user
so this change does not cause any incompatibilities.

Hopefully this change will help code that was written for draft 4
fail gracefully if the programmer ignores the compiler warning about
the change in the level of indirection for the argument passed to
pthread_detach(). I got burnt, so I fixed then (expletive deleted)
thing.

These functions comply with the revised standard. That should shut
Terry up!

Add sched_yield() witch is the draft 10 equivalent of pthread_yield()
from draft 4. Move some of the schedule definitions to sched.h which
is a POSIX header.

remove prototype for nanosleep(), it's visible in unistd.h now.

Submitted by: John Birrell
uthreads update from the author.

Moved enum pthread_mutextype to pthread.h.
Add pthread_mutexattr_default definition.

Submitted by: John Birrell <cimaxp1!jb@werple.net.au>

Here are the diffs for libc_r to get it one step closer to P1003.1c
These make most of the thread/mutex/condvar structures opaque to the
user. There are three functions which have been renamed with _np
suffixes because they are extensions to P1003.1c (I did them for JAVA,
which needs to suspend/resume threads and also start threads suspended).

I've created a new header (pthread_np.h) for the non-POSIX stuff.

The egrep tags stuff in /usr/src/lib/libc_r/Makefile that I uncommented
doesn't work. I think its best to delete it. I don't think libc_r needs
tags anyway, 'cause most of the source is in libc which does have tags.

also:

Here's the first batch of man pages for the thread functions.
The diff to /usr/src/lib/libc_r/Makefile removes some stuff that was
inherited from /usr/src/lib/libc/Makefile that should only be done with
libc.

also:

I should have sent this diff with the pthread(3) man page.
It allows people to type

make -DWANT_LIBC_R world

to get libc_r built with the rest of the world. I put this in the
pthread(3) man page. The default is still not to build libc_r.


also:
The diff attached adds a pthread(3) man page to /usr/src/share/man/man3.
The idea is that without libc_r installed, this man page will give people
enough info to know that they have to build libc_r.

Reviewed by: julian
Submitted by: john birrel

One version of the pthreads library
another will follow with differnt actions under some cases..
not QUITE complete