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)

Remove 3rd clause, renumber, ok per email

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

pthread api should return error code in return value, not in errno.

Fix a bogus comment, sigmask must be maintained correctly,
it will be inherited in pthread_create.

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

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

Avoid accessing user provided parameters in critical region.

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().

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

Make pthread_sigmask(3) operate on the thread signal mask, not the process
signal mask.

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

To be consistent, use the __weak_reference macro from <sys/cdefs.h>
instead of #pragma weak to create weak definitions.

Suggested by: bde

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

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

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

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.

$Id$ -> $FreeBSD$

Add RCS IDs to those files without them.
Fix copyrights (s/REGENTS/AUTHOR).

Suggested by: tg
Approved by: jb

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!

Submitted by: John Birrell
uthreads update from the author.