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History log of /src/lib/libpthread/pthread_mutex.c
RevisionDateAuthorComments
 1.83  10-Apr-2022  riastradh pthread: Nix trailing whitespace.
 1.82  12-Feb-2022  riastradh libpthread: Move namespacing include to top of .c files.

Stuff like libc's namespace.h, or atomic_op_namespace.h, which does
namespacing tricks like `#define atomic_cas_uint _atomic_cas_uint',
has to go at the top of each .c file. If it goes in the middle, it
might be too late to affect the declarations, and result in compile
errors.

I tripped over this by including <sys/atomic.h> in mips
<machine/lock.h>.

(Maybe we should create a new pthread_namespace.h file for the
purpose, but this'll do for now.)
 1.81  11-Jun-2020  ad Adjust memory barriers.
 1.80  10-Jun-2020  ad - Make pthread_condvar and pthread_mutex work on the stack rather than in
pthread_t, so there's less chance of bad things happening if someone calls
(for example) pthread_cond_broadcast() from a signal handler.

- Remove all the deferred waiter handling except for the one case that really
matters which is transferring waiters from condvar -> mutex on wakeup, and
do that by splicing the condvar's waiters onto the mutex.

- Remove the mutex waiters bit as it's another complication that's not
strictly needed.
 1.79  03-Jun-2020  ad Deal with a couple of problems with threads being awoken early due to
timeouts or cancellation where:

- The restarting thread calls _lwp_exit() before another thread gets around
to waking it with _lwp_unpark(), leading to ESRCH (observed by joerg@).
(I may have removed a similar check mistakenly over the weekend.)

- The restarting thread considers itself gone off the sleep queue but
at the same time another thread is part way through waking it, and hasn't
fully completed that operation yet by setting thread->pt_mutexwait = 0.
I think that could have potentially lead to the list of waiters getting
messed up given the right circumstances.
 1.78  01-Jun-2020  ad In the interests of reliability simplify waiter handling more and redo
condvars to manage the list of waiters with atomic ops.
 1.77  16-May-2020  ad - Try to eliminate a hang in "parked" I've been seeing while stress testing.
Centralise wakeup of deferred waiters in pthread__clear_waiters() and use
throughout libpthread. Make fewer assumptions. Be more conservative in
pthread_mutex when dealing with pending waiters.

- Remove the "hint" argument everywhere since the kernel doesn't use it any
more.
 1.76  16-Feb-2020  kamil Revert "Enhance the pthread(3) + malloc(3) init model"

It is reported to hand on aarch64 with gzip.
 1.75  15-Feb-2020  kamil Enhance the pthread(3) + malloc(3) init model

Separate the pthread_atfork(3) call from pthread_tsd_init()
and move it into a distinct function.

Call inside pthread__init() late TSD initialization route, just after
"pthread_atfork(NULL, NULL, pthread__fork_callback);".

Document that malloc(3) initialization is now controlled again and called
during the first pthread_atfork(3) call.

Remove #if 0 code from pthread_mutex.c as we no longer initialize malloc
prematurely.
 1.74  01-Feb-2020  kamil Revert previous

'git grep' breaks now.
 1.73  01-Feb-2020  kamil Remove 'ifdef 0' hacks

It is no longer needed as the proper fix avoiding premature malloc()
landed the sources.
 1.72  31-Jan-2020  kamil Refactor libpthread checks for invalid arguments

Switch from manual functions to pthread__error().
 1.71  31-Jan-2020  christos In the same spirit as the previous pthread_mutex_init change for jemalloc,
make pthread_mutexattr_init do always a full initialization, so that the
attribute that will be used later when we become threaded is properly
initialized.
 1.70  29-Jan-2020  kamil Use pthread_mutexattr_t and pthread_mutex_t magic fields

Validate _PT_MUTEX_MAGIC in pthread_mutex_t and _PT_MUTEXATTR_MAGIC
in pthread_mutexattr_t accordingly.
 1.69  29-Jan-2020  kamil Mark destroyed pthread_mutexattr_t as dead
 1.68  25-Jan-2020  ad Adjustment to previous: don't call _lwp_unpark_all() with nwaiters == 0.
 1.67  25-Jan-2020  ad pthread__mutex_unlock_slow(): ignore the DEFERRED bit. It's only purpose
is to get the thread to go through the slow path. If there are waiters,
process them there and then. Should not affect well behaved apps. Maybe
of help for:

PR bin/50350: rump/rumpkern/t_sp/stress_{long,short} fail on Core 2 Quad
 1.66  13-Jan-2020  ad Rip out some very ambitious optimisations around pthread_mutex that are
don't buy much. This stuff is hard enough to get right in the kernel let
alone userspace, and I don't trust that it's right.
 1.65  05-Mar-2019  christos branches: 1.65.2;
Jemalloc initializes mutexes before we become threaded and expects to use
them later.
 1.64  08-Dec-2017  kre branches: 1.64.4;

Deal with more lwp_park() timestamp unconsting
 1.63  31-Oct-2016  christos Don't spin if we already own the mutex, otherwise we will get stuck spinning
forever, fixes timemutex{1,2} tests.
 1.62  17-Jul-2016  skrll Use anonymous union for ptm_ceiling and old __pthread_spin_t field to
maintain backward compatibility and fix hppa build. hppa has an non-
integer type __pthread_spin_t
 1.61  16-Jul-2016  skrll KNF
 1.60  03-Jul-2016  christos branches: 1.60.2;
GSoC 2016 Charles Cui: Implement thread priority protection based on work
by Andy Doran. Also document the get/set pshared thread calls as not
implemented, and add a skeleton implementation that is disabled.
XXX: document _sched_protect(2).
 1.59  03-Feb-2014  rmind pthread__mutex_lock_slow: fix the handling of a potential race with the
non-interlocked CAS in the fast unlock path -- it is unsafe to test for
the waiters-bit while the owner thread is running, we have to spin for
the owner or its state change to be sure about the presence of the bit.
Split off the logic into the pthread__mutex_setwaiters() routine.

This is a partial fix to the named lockup problem (also see PR/44756).
It seems there is another race which can be reproduced on faster CPUs.
 1.58  31-Jan-2014  christos remove compatibility code for handling CLOCK_MONOTONIC and handle it in the
syscall directly.
 1.57  31-Jan-2014  christos PR/44756: Sad Clouds: Prevent leakage of errno = ESRCH from _lwp_park. This
has two parts:
- in pthread_cond_timedwait() if the thread we are trying to unpark
exited, retry the the _lwp_park call without it.
- pthread_mutex() was affecting errno since it is calling _lwp_park()
from pthread_mutex_lock_slow(). preserve the original errno.
Note that the example problem still causes an occassional deadlock on machines
with many CPUs and it is the same deadlock we observe with named.
 1.56  21-Mar-2013  christos - Allow libpthread to be dlopened again, by providing libc stubs to libpthread.
- Fail if the dlopened libpthread does pthread_create(). From manu@
- Discussed at length in the mailing lists; approved by core@
- This was chosen as the least intrusive patch that will provide
the necessary functionality.
XXX: pullup to 6
 1.55  06-Mar-2013  yamt add comments
whitespace
 1.54  16-Aug-2012  matt branches: 1.54.2;
Add a pthread__smt_wake and add support for it on arm along with
pthread__smt_pause. These are implemented using the ARM instructions
SEV (wake) and WFE (pause). These are treated as NOPs on ARM CPUs that
don't support them.
 1.53  13-Mar-2012  joerg Move the pthread_once alias where it belongs.
 1.52  12-Mar-2012  joerg Move pthread_once implementation into a separate file, it doesn't depend
on the mutex implementation in any way.
 1.51  02-Aug-2008  matt branches: 1.51.2; 1.51.4; 1.51.6; 1.51.22;
Change pthread_mutex_t to use the amount of space as and be congruent to
the version used in the SA version of pthreads. This preserves binary
compatibility between both versions of the library.
 1.50  25-May-2008  ad PR lib/38741 priority inversion in libpthread breaks apps that use
SCHED_FIFO threads

- Change condvar sync so that we never take the condvar's spinlock without
first holding the caller-provided mutex. Previously, the spinlock was only
taken without the mutex in an error path, but it was enough to trigger the
problem described in the PR.

- Even with this change, applications calling pthread_cond_signal/broadcast
without holding the interlocking mutex are still subject to the problem
described in the PR. POSIX discourages this saying that it leads to
undefined scheduling behaviour, which seems good enough for the time being.

- Elsewhere, use a hash of mutexes instead of per-object spinlocks to
synchronize entry/exit from sleep queues.

- Simplify how sleep queues are maintained.
 1.49  25-May-2008  ad Add some general comments about the mutex implementation.
 1.48  28-Apr-2008  martin branches: 1.48.2;
Remove clause 3 and 4 from TNF licenses
 1.47  07-Mar-2008  ad branches: 1.47.2;
pthread__mutex_lock_slow:

- don't stop spinning if there are already waiters on the mutex, there is
no point.
- cosmetic change.
 1.46  23-Feb-2008  ad Fix pthread_mutex_trylock() for recursive mutexes. PR lib/38087.
Based on a patch provided by rafal@.
 1.45  14-Feb-2008  ad branches: 1.45.2;
Adjust mutex/rwlock definitions to match reality now that there is only
one implementation of each. PR lib/38030.
 1.44  10-Feb-2008  ad - Remove libpthread's atomic ops.
- Remove the old spinlock-based mutex and rwlock implementations.
- Use the atomic ops from libc.
 1.43  25-Jan-2008  rafal Make this compile after Andrew's fix (remove now-unused variables)
 1.42  25-Jan-2008  ad pthread_mutex_lock_slow: remove "deliberate deadlock" code that's not
needed with 1:1. PR lib/37524.
 1.41  08-Jan-2008  christos add missing static decls.
 1.40  05-Jan-2008  ad machine/lock.h, not sys/lock.h
 1.39  24-Dec-2007  ad - Fix pthread_rwlock_trywrlock() which was broken.

- Add new functions: pthread_mutex_held_np, mutex_owner_np, rwlock_held_np,
rwlock_wrheld_np, rwlock_rdheld_np. These match the kernel's locking
primitives and can be used when porting kernel code to userspace.

- Always create LWPs detached. Do join/exit sync mostly in userland. When
looped on a dual core box this seems ~30% quicker than using lwp_wait().
Reduce number of lock acquire/release ops during thread exit.
 1.38  19-Nov-2007  ad Remove the debuglog stuff. ktrace is more useful now.
 1.37  13-Nov-2007  ad For PR bin/37347:

- Override __libc_thr_init() instead of using our own constructor.
- Add pthread__getenv() and use instead of getenv(). This is used before
we are up and running and unfortunatley getenv() takes locks.

Other changes:

- Cache the spinlock vectors in pthread__st. Internal spinlock operations
now take 1 function call instead of 3 (i386).
- Use pthread__self() internally, not pthread_self().
- Use __attribute__ ((visibility("hidden"))) in some places.
- Kill PTHREAD_MAIN_DEBUG.
 1.36  13-Sep-2007  ad Add a per-mutex deferred wakeup flag so that threads doing something like
the following do not wake other threads early:

pthread_mutex_lock(&mutex);
pthread_cond_broadcast(&cond);
foo = malloc(100); /* takes libc mutexes */
pthread_mutex_unlock(&mutex);
 1.35  11-Sep-2007  ad Fix inverted test after merge of nick-csl-alignment.
 1.34  10-Sep-2007  skrll Merge nick-csl-alignment.
 1.33  08-Sep-2007  ad - Get rid of self->pt_mutexhint and use pthread__mutex_owned() instead.
- Update some comments and fix minor bugs. Minor cosmetic changes.
- Replace some spinlocks with mutexes and rwlocks.
- Change the process private semaphores to use mutexes and condition
variables instead of doing the synchronization directly. Spinlocks
are no longer used by the semaphore code.
 1.32  07-Sep-2007  ad - Don't take the mutex's spinlock (ptr_interlock) in pthread_cond_wait().
Instead, make the deferred wakeup list a per-thread array and pass down
the lwpid_t's that way.

- In pthread_cond_wait(), take the mutex before dealing with early wakeup.
In this way there should never be contention on the CV's spinlock if
the app follows POSIX rules (there should only be contention on the
user-provided mutex).

- Add a port of the kernel's rwlocks. The rwlock's spinlock is only taken if
there is contention. This is enabled where atomic ops are available. Right
now that is only i386 and amd64 because I don't have other hardware to
test with. It's trivial to add stubs for other architectures as long as
they have compare-and-swap. When we have proper atomic ops the old rwlock
code can be removed.

- Add a new mutex implementation that's similar to the kernel's mutexes, but
uses compare-and-swap to maintain the waiters list, so no spinlocks are
involved. Same caveats apply as for the rwlocks.
 1.31  16-Aug-2007  ad branches: 1.31.2;
One more micro-optimization..
 1.30  16-Aug-2007  ad Trim fat off libpthread internal spinlock operations. Makes a mesurable
improvement across the board.
 1.29  04-Aug-2007  ad branches: 1.29.2;
Some significant performance improvements, and a fix for a race with pthread
detach/join.

- Make mutex acquire spin for a short time, as done with spinlocks.
- Make the number of spins controllable with the env var PTHREAD_NSPINS.
- Reduce the amount of time that libpthread internal spinlocks are held.
- Rely more on the barrier effects of park/unpark to avoid taking spinlocks.
- Simplify the locking around pthreads and the global queues.
- Align per-thread sync data on a 128 byte boundary.
- Offset thread stacks by a small amount to try and reduce cache thrash.
 1.28  24-Mar-2007  ad branches: 1.28.2;
- Test+branch is usually cheaper than making an indirect function call,
so avoid making them.
- When parking an LWP on a condition variable, point the hint argument at
the mutex's waiters queue. Chances are we will be awoken from that later.
 1.27  20-Mar-2007  ad - Maintain a per-thread pointer to the last mutex acquired by the app, to
be used only as as a hint. Clear the pointer when releasing the mutex.
- When releasing a mutex, wake all waiters. Makes it possible to tranfer
waiters from another object to a mutex.
 1.26  05-Mar-2007  ad Update to match changed pthread__park() interface.
 1.25  02-Mar-2007  ad Remove the PTHREAD_SA option. If M:N threads is reimplemented it's
better off done with a seperate library.
 1.24  24-Dec-2006  ad Fix bugs with and improve upon previous.
 1.23  23-Dec-2006  ad Conditionalised support for 1:1 threads. Needs associated kernel changes
and more work to be useful.
 1.22  22-Aug-2006  wrstuden branches: 1.22.2; 1.22.4;
Close a window in which we can not notice a recently-slept-on-our
mutex thread, thus leaving a thread sleeping on an unlocked mutex.

Reviewed by myself and Christos.

Problem reported by Arne H. Juul, arnej at pvv dot ntnu dot no,
in PR 26208. This fix represents option 1 presented in the PR.
 1.21  19-Oct-2005  chs branches: 1.21.2;
starting the pthread library (ie. calling pthread__start()) before
any threads are created turned out to be not such a good idea.
there are stronger requirements on what has to work in a forked child
while a process is still single-threaded. so take all that stuff
back out and fix the problems with single-threaded programs that
are linked with libpthread differently, by checking if the library
has been started and doing completely different stuff if it hasn't been:
- for pthread_rwlock_timedrdlock(), just fail with EDEADLK immediately.
- for sem_wait(), the only thing that can unlock the semaphore is a
signal handler, so use sigsuspend() to wait for a signal.
- for pthread_mutex_lock_slow(), just go into an infinite loop
waiting for signals.

I also noticed that there's a "sem2" test that has never worked in its
single-threaded form. the problem there is that a signal handler tries
to take a sem_t interlock which is already held when the signal is received.
fix this too, by adding a single-threaded case for sig_trywait() that
blocks signals instead of using the userland interlock.
 1.20  16-Oct-2005  chs in pthread_mutex_lock_slow(), pthread_rwlock_timedrdlock() and sem_wait(),
call pthread__start() if it hasn't already been called. this avoids
an internal assertion from the library if these routines are used
before any threads are created and they need to sleep.
fixes PR 20256, PR 24241, PR 25722, PR 26096.
 1.19  16-Jul-2005  nathanw Add cancellation protection to pthread_once() as per the standard; if
the once routine is cancelled, the effect on once_control is as if
pthread_once() was never called.

Bug report and fix from PR lib/30734.
 1.18  14-Mar-2004  cl branches: 1.18.6;
add libpthread part of concurrency support for SA on MP systems
- enable concurrency according to environment variable PTHREAD_CONCURRENCY
- add idle VP wakeup if there are additional jobs and idle VPs
- make reidlequeue per VP
- enable spinning for locks
- fix race condition in alarm processing
- fix race condition in mutex locking
- make debugging output line buffered and add VP prefix to debug lines
 1.17  24-Nov-2003  cl Update mutex/rwlock/sem code to match recent change in cond code.
 1.16  27-May-2003  christos add missing notreached lint comment.
 1.15  16-May-2003  nathanw Separately report unlocking an unlocked mutex and unlocking a mutex
owned by another thread.
 1.14  23-Apr-2003  nathanw Use pthread__error() instead of pthread__abort().
 1.13  18-Apr-2003  nathanw More agressive assertions. Change a number of detected conditions, which
officially have undefined behavior, from returning an error code to raising
an assertion failure.
Also, don't bother to explicitly test for (illegal) null pointers and return
an error; they'll bomb out soon enough.
 1.12  16-Apr-2003  nathanw pthread_mutex_trylock(): It's not an error to call trylock() on a
mutex already locked by the calling thread, even for non-recursive
mutexes.
 1.11  16-Apr-2003  nathanw When a thread sleeps on a mutex or cv, have it put itself on the
front of the sleep queue rather than the back. This is more
cache-friendly behavior and within the (lack of) constraints on wakeup
ordering imposed on equal-priority threads.
 1.10  08-Mar-2003  lukem add __RCSID()
 1.9  15-Feb-2003  nathanw Remove unnecessary inclusion of <assert.h>.
 1.8  31-Jan-2003  nathanw Mutex tuneup.

* Use a double-checked locking technique to avoid taking
the interlock in pthread_mutex_unlock().

* In pthread_mutex_lock() and pthread_mutex_trylock(), only store the
stack pointer, not the thread ID, in ptm_owner. Do the translation
to a thread ID in the slow-lock, errorcheck, and recursive mutex
cases rather than in the common path.

* Juggle where pthread__self() is called, to move it out of the fast path.

Overall, this means that neither pthread_self() nor
pthread_spin[un]lock() are used in the course of locking and unlocking
an uncontested mutex. Speeds up the fast path by 40-50%, and
eliminates about 98% of spinlocks used by a couple of large threaded
applications.

(Still a GET_MUTEX_PRIVATE() in the fast path... perhaps the type
should be in the main body of the mutex).
 1.7  27-Jan-2003  nathanw Add debug counters for mutex and condvar operations.
 1.6  22-Jan-2003  scw Need to include <string.h> for memcmp() prototype.
 1.5  19-Jan-2003  thorpej Fix typo.
 1.4  19-Jan-2003  thorpej Add mutexattr_init(), mutexattr_destroy(), and mutexattr_settype() (recursive
mutexes are used by the X libraries).
 1.3  18-Jan-2003  christos de-lint
 1.2  18-Jan-2003  thorpej Merge the nathanw_sa branch.
 1.1  05-Mar-2001  nathanw branches: 1.1.2;
file pthread_mutex.c was initially added on branch nathanw_sa.
 1.1.2.20  14-Jan-2003  thorpej Move a comment to a more logical location.
 1.1.2.19  13-Jan-2003  thorpej Implement recursive and errorcheck mutexes.
 1.1.2.18  09-Jan-2003  thorpej Remove trailing semicolon from __strong_alias().
 1.1.2.17  08-Jan-2003  thorpej Rewrite the way libpthread provides thread primitives to libc, using
strong and weak aliases (the way cancelation points are handled).

Work around lame Unix static library semantics which could cause
the wrong thread primitives or cancelation point functions to be
included in a statically-linked program.

THIS IS AN ABI CHANGE. People running the nathanw_sa branch should
ensure that their libc and libpthread are in sync after updating.
 1.1.2.16  30-Dec-2002  thorpej Add support for using RAS lock primitives on uniprocessors where
RAS is available.
 1.1.2.15  26-Oct-2002  nathanw Whitespace in comments.
 1.1.2.14  23-Oct-2002  nathanw Revert previous. There's still a race condition whose avoidance requires
checking the blocked queue with the interlock held.
 1.1.2.13  22-Oct-2002  nathanw Speed up pthread_mutex_unlock() similarly to what was done to
pthread_mutex_lock(): heavily optimize for the case of a mutex with no
waiters, and defer the waiter case to a separate function.

Uncontested mutexes now no longer use library spin locks.
 1.1.2.12  04-Oct-2002  nathanw Tweak pthread_mutex_lock(): Move the "slow" code to another function
and only call pthread_self() inside that function.

Don't use pthread_self() to track ownership; just stash the stack
pointer. Translation to thread IDs can be done post-mortem if
necessary (Thanks to Greg Hudson for pointing this out).
 1.1.2.11  26-Apr-2002  nathanw Track the synchronization object being slept on.
 1.1.2.10  11-Apr-2002  nathanw Revert weak aliases.
 1.1.2.9  25-Mar-2002  nathanw Oops, that function is pthread_once(), not pthread_mutex_once().
 1.1.2.8  25-Mar-2002  nathanw Provide interfaces to libc.
 1.1.2.7  28-Jan-2002  nathanw Cancellation support.
This includes implementing pthread_cancel() and pthread_testcancel(),
making pthread_join() and pthread_cond_wait() cancellation points,
introducing new states to distinguish waiting on a sleep queue
from waiting in the kernel, and introducing a locking protocol around
changing a thread's run state.
 1.1.2.6  08-Aug-2001  nathanw Implement pthread_once().
 1.1.2.5  25-Jul-2001  nathanw Stadardize and clean up use of ERRORCHECK.
Implement pthread_{cond,mutex}attr_{init,destroy} and make the relevant
functions check for their validity.
(No non-default attribute values are supported, but these interfaces
are required anyway).
 1.1.2.4  24-Jul-2001  nathanw Remove some unnecessary includes.
Prefix some application-visible preprocessor symbols with an underscore.

Modify pthread_mutex_unlock() to only wake up one waiter.
 1.1.2.3  13-Jul-2001  nathanw Note copyright.
Standardize RCS IDs.
 1.1.2.2  13-Jul-2001  nathanw Convert to new queue type.

Remove a level of indirection in the definition and use of
pthread_mutex_t.

Add a note about Pthreads memory visibility rules.

Use an optimistic simple-lock approach for locking mutexes. Should be
faster in the common case.
 1.1.2.1  05-Mar-2001  nathanw The beginnings of a scheduler activations-based pthread library.
 1.18.6.2  25-Aug-2006  ghen Pull up following revision(s) (requested by wrstuden in ticket #1474):
lib/libpthread/pthread_mutex.c: revision 1.22
Close a window in which we can not notice a recently-slept-on-our
mutex thread, thus leaving a thread sleeping on an unlocked mutex.
Reviewed by myself and Christos.
Problem reported by Arne H. Juul, arnej at pvv dot ntnu dot no,
in PR 26208. This fix represents option 1 presented in the PR.
 1.18.6.1  01-Nov-2005  jmc branches: 1.18.6.1.2;
Pullup revs 1.20-1.21 (requested by chs in ticket #926)
In pthread_mutex_lock_slow(), pthread_rwlock_timedrdlock() and sem_wait(),
call pthread__start() if it hasn't already been called. this avoids
an internal assertion from the library if these routines are used
before any threads are created and they need to sleep.
PR#20256, PR#24241, PR#25722, PR#26096

Fix the interaction between sigtimedwait() and pthread_kill(),
both waking up a sleeping thread and avoiding going to sleep if
a signal is already pending. PR#30348

In pthread_kill() and pthread_suspend_np(), return without doing anything
f the target thread is a zombie.
In all the functions that didn't do so already, verify a pthread_t before
dereferencing it (under #ifdef ERRORCHECK, since these checks are not
mandated by the standard).

Starting the pthread library (ie. calling pthread__start()) before
any threads are created turned out to be not such a good idea.
there are stronger requirements on what has to work in a forked child
while a process is still single-threaded. so take all that stuff
back out and fix the problems with single-threaded programs that
are linked with libpthread differently, by checking if the library
has been started and doing completely different stuff if it hasn't been:
- for pthread_rwlock_timedrdlock(), just fail with EDEADLK immediately.
- for sem_wait(), the only thing that can unlock the semaphore is a
signal handler, so use sigsuspend() to wait for a signal.
- for pthread_mutex_lock_slow(), just go into an infinite loop
waiting for signals.

If mlock() fails in pthread_create(), return EAGAIN instead of
failing an assertion.
 1.18.6.1.2.1  25-Aug-2006  ghen Pull up following revision(s) (requested by wrstuden in ticket #1474):
lib/libpthread/pthread_mutex.c: revision 1.22
Close a window in which we can not notice a recently-slept-on-our
mutex thread, thus leaving a thread sleeping on an unlocked mutex.
Reviewed by myself and Christos.
Problem reported by Arne H. Juul, arnej at pvv dot ntnu dot no,
in PR 26208. This fix represents option 1 presented in the PR.
 1.21.2.1  25-Aug-2006  ghen Pull up following revision(s) (requested by wrstuden in ticket #52):
lib/libpthread/pthread_mutex.c: revision 1.22
Close a window in which we can not notice a recently-slept-on-our
mutex thread, thus leaving a thread sleeping on an unlocked mutex.
Reviewed by myself and Christos.
Problem reported by Arne H. Juul, arnej at pvv dot ntnu dot no,
in PR 26208. This fix represents option 1 presented in the PR.
 1.22.4.2  04-Nov-2007  wrstuden Check in changes to locking behavior.

pthread__sched() now takes a parameter indicating if the run queue is
already locked. Useful in cases where we already hold pthread__runqueue_lock.

pthread__suspend() now requires callers explicitly lock pthread__runqueue_lock
so we avoid issues with locking order regarding pt_statelock.

Adjsut our lock hierarchy. pthread__runqueue_lock is now above
pt_statelock, triggering the above adjustments. Adjust a lot of routines
as a result. Also move pt_siglock way up in the hierarchy, making
pthread__kill() not violate locking. Add a few extra locks to the list.

Adjust a botch in how pthread_join() used pthread-spintrylock().

pthread_cancel() now correctly walks up the locks with thread->pt_sleeplock.
We can't just lock it, as it points to a lock in the top locking rung. So
try locking, and if it fails, unlock and re-lock. Add code to cope with
the target thread not being in the expected state (which was on a
blocked queue) after we get all the locks.

Add comments to describe what's going on in places that I got confused.

Now that pt_statelock is lower in the locking order than
pthread__runqueue_lock, we can explicitly lock a thread's state before
we take it off the run queue. Adjust sched_yield() accordingly and
add some locking calls that were commented out before (as they'd have
been locking violations).

pthread_next(): now that we can lock the state lock while holding the run
queue lock, do so. Set a thread's state to PT_STATE_RUNNING before we
pull it off the run queue. Since we always are going to switch to it,
set pt_vpid and pt_lastlwp while setting the state. pthread_next
callers now _don't_ set these values.

pthread__kill(): grab pthread__runqueue_lock before target->pt_statelock.
If we want to target a thread that is on a blocked queue, do the
pthread_spintrylock() dance. Unlock all three locks we're running around
with, lock target->pt_sleeplock, then re-lock them all. After we lock,
make sure that the thread's still on a blocked queue before proceeding. If
it's not, either exit (if we wanted to wake out of sigtimedwait())
or start it all over. If the thread has gone live, it may have blocked
our signal and it'd be quite weird to get a signal you'd disabled, just
because the signaller had been running before you blocked it.
 1.22.4.1  10-Sep-2007  wrstuden Check in first step towards having pthread_kill() kill a thread running
on another CPU.

This change adds initial support for deferred signal handling. Just before
we go to sleep and while we hold &self->pt_statelock, check to see if we
have any deferred signals (blocked signals) pending. These are signals
that are not masked in our mask and which have been sent to us. We
were running when they came in. Further, since they are being handled
this way, there's a signal handler defined for them.

So unlock, run the signal handler(s), then carry on.

For condition variables, we consider this a spurious wakeup, so we just
return 0, having not unlocked the mutex. We run the handler with
the mutex held. This shouldn't matter, as you aren't supposed to play
with mutexes in signal handlers. :-)

For nanosleep(), we just process signals, then go to sleep.

For all other cases, we are in a loop with some external predicate. So
we process the signal then roll around the loop to see if it still applies.

In sched_yield(), spin until all deferred signals are gone. Since we hold
self->pt_statelock and that lock has to be held before sending a deferred
signal, no new deferred signals will come in until we're asleep.

While here, be more careful about locking while changing pt_state
to PT_STATE_RUNNING. Grab pt_statelock while doing it, and also set
next->pt_vpid to self->pt_vpid holding the same lock. Will make
the test to determine how to deliver a signal work right (since
a thread's vpid will soon matter in the general case). No longer
set next->pt_vpid in pthread__next().
 1.22.2.1  16-Sep-2008  bouyer Sync with the following revisions (requested by skrll in ticket #1196):
gnu/dist/gdb removed
gnu/usr.bin/gdb53 removed
distrib/cats/instkernel/Makefile 1.14.6.1
gnu/dist/gdb6/bfd/config.bfd 1.3.6.1
gnu/dist/gdb6/bfd/elfxx-sparc.c 1.1.1.2.6.1
gnu/dist/gdb6/bfd/elfxx-sparc.h 1.1.1.2.6.1
gnu/dist/gdb6/gdb/Makefile.in 1.2.2.1.2.2
gnu/dist/gdb6/gdb/alpha-tdep.c 1.1.1.2.6.1
gnu/dist/gdb6/gdb/alpha-tdep.h 1.1.1.2.6.1
gnu/dist/gdb6/gdb/alphabsd-nat.c 1.1.1.2.6.2
gnu/dist/gdb6/gdb/alphabsd-nat.h 1.1.2.1
gnu/dist/gdb6/gdb/alphabsd-tdep.c 1.1.1.2.6.1
gnu/dist/gdb6/gdb/alphabsd-tdep.h 1.1.1.2.6.1
gnu/dist/gdb6/gdb/alphanbsd-nat.c 1.1.2.1
gnu/dist/gdb6/gdb/alphanbsd-tdep.c 1.1.1.2.6.1
gnu/dist/gdb6/gdb/amd64-nat.c 1.1.1.2.6.1
gnu/dist/gdb6/gdb/amd64bsd-nat.c 1.1.1.2.6.1
gnu/dist/gdb6/gdb/amd64nbsd-nat.c 1.1.1.2.6.3
gnu/dist/gdb6/gdb/amd64nbsd-tdep.c 1.1.1.2.6.1
gnu/dist/gdb6/gdb/arm-tdep.h 1.1.1.2.6.1
gnu/dist/gdb6/gdb/armbsd-tdep.c 1.1.2.1
gnu/dist/gdb6/gdb/armnbsd-nat.c 1.1.1.2.6.2
gnu/dist/gdb6/gdb/armnbsd-tdep.c 1.1.1.2.6.1
gnu/dist/gdb6/gdb/configure 1.1.1.2.6.1
gnu/dist/gdb6/gdb/configure.ac 1.1.1.2.6.1
gnu/dist/gdb6/gdb/i386bsd-nat.c 1.1.1.2.6.1
gnu/dist/gdb6/gdb/i386nbsd-tdep.c 1.1.1.2.6.1
gnu/dist/gdb6/gdb/m68kbsd-nat.c 1.1.1.2.6.2
gnu/dist/gdb6/gdb/mipsnbsd-nat.c 1.1.1.2.6.2
gnu/dist/gdb6/gdb/nbsd-thread.c 1.1.2.3
gnu/dist/gdb6/gdb/ppcnbsd-nat.c 1.1.1.2.6.2
gnu/dist/gdb6/gdb/ppcnbsd-tdep.c 1.3.6.1
gnu/dist/gdb6/gdb/sh-tdep.c 1.1.1.2.6.1
gnu/dist/gdb6/gdb/shnbsd-nat.c 1.1.1.2.6.3
gnu/dist/gdb6/gdb/shnbsd-tdep.c 1.1.1.2.6.4
gnu/dist/gdb6/gdb/shnbsd-tdep.h 1.1.1.2.6.1
gnu/dist/gdb6/gdb/sparc-nat.c 1.1.1.2.6.1
gnu/dist/gdb6/gdb/sparc64nbsd-nat.c 1.1.1.2.6.2
gnu/dist/gdb6/gdb/sparcnbsd-nat.c 1.1.1.2.6.2
gnu/dist/gdb6/gdb/tramp-frame.h 1.1.1.2.6.1
gnu/dist/gdb6/gdb/vaxbsd-nat.c 1.1.1.2.6.2
gnu/dist/gdb6/gdb/config/alpha/nbsd.mh 1.1.1.2.6.1
gnu/dist/gdb6/gdb/config/arm/nbsd.mt 1.1.1.1.6.1
gnu/dist/gdb6/gdb/config/arm/nbsdelf.mh 1.1.1.1.6.1
gnu/dist/gdb6/gdb/config/i386/nbsd64.mh 1.1.1.1.6.1
gnu/dist/gdb6/gdb/config/m68k/nbsdelf.mh 1.1.1.1.6.1
gnu/dist/gdb6/gdb/config/mips/nbsd.mh 1.1.1.1.6.1
gnu/dist/gdb6/gdb/config/powerpc/nbsd.mh 1.1.1.2.6.1
gnu/dist/gdb6/gdb/config/sh/nbsd.mh 1.1.1.1.6.2
gnu/dist/gdb6/gdb/config/sh/tm-nbsd.h 1.1.1.1.6.1
gnu/dist/gdb6/gdb/config/sparc/nbsd64.mh 1.1.1.1.6.1
gnu/dist/gdb6/gdb/config/sparc/nbsdelf.mh 1.1.1.1.6.1
gnu/dist/gdb6/gdb/config/vax/nbsdelf.mh 1.1.1.1.6.1
gnu/dist/gdb6/opcodes/configure 1.1.1.2.6.1
gnu/dist/gdb6/opcodes/configure.in 1.1.1.2.6.1
gnu/usr.bin/Makefile 1.126.4.1
gnu/usr.bin/gdb6/arch/alpha/config.h 1.3.4.1
gnu/usr.bin/gdb6/arch/alpha/defs.mk 1.2.6.1
gnu/usr.bin/gdb6/arch/alpha/init.c 1.2.6.1
gnu/usr.bin/gdb6/arch/alpha/nm.h 1.2.6.1
gnu/usr.bin/gdb6/arch/arm/defs.mk 1.2.6.2
gnu/usr.bin/gdb6/arch/arm/init.c 1.1.6.1
gnu/usr.bin/gdb6/arch/armeb/config.h 1.1.6.2
gnu/usr.bin/gdb6/arch/armeb/defs.mk 1.1.6.3
gnu/usr.bin/gdb6/arch/armeb/init.c 1.1.6.2
gnu/usr.bin/gdb6/arch/armeb/tm.h 1.1.6.2
gnu/usr.bin/gdb6/arch/armeb/version.c 1.1.6.2
gnu/usr.bin/gdb6/arch/i386/defs.mk 1.4.4.1
gnu/usr.bin/gdb6/arch/i386/init.c 1.3.6.1
gnu/usr.bin/gdb6/arch/m68000/config.h 1.1.6.2
gnu/usr.bin/gdb6/arch/m68000/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/arch/m68000/init.c 1.1.6.2
gnu/usr.bin/gdb6/arch/m68000/tm.h 1.1.6.2
gnu/usr.bin/gdb6/arch/m68000/version.c 1.1.6.2
gnu/usr.bin/gdb6/arch/m68k/defs.mk 1.1.4.1
gnu/usr.bin/gdb6/arch/m68k/init.c 1.1.4.1
gnu/usr.bin/gdb6/arch/mipseb/config.h 1.3.4.1
gnu/usr.bin/gdb6/arch/mipseb/defs.mk 1.2.6.2
gnu/usr.bin/gdb6/arch/mipseb/init.c 1.2.6.2
gnu/usr.bin/gdb6/arch/mipsel/config.h 1.2.6.3
gnu/usr.bin/gdb6/arch/mipsel/defs.mk 1.2.6.3
gnu/usr.bin/gdb6/arch/mipsel/init.c 1.2.6.3
gnu/usr.bin/gdb6/arch/mipsel/tm.h 1.2.6.2
gnu/usr.bin/gdb6/arch/mipsel/version.c 1.2.6.2
gnu/usr.bin/gdb6/arch/powerpc/defs.mk 1.3.6.1
gnu/usr.bin/gdb6/arch/powerpc/init.c 1.3.6.1
gnu/usr.bin/gdb6/arch/sh3eb/config.h 1.2.2.2
gnu/usr.bin/gdb6/arch/sh3eb/defs.mk 1.2.8.3
gnu/usr.bin/gdb6/arch/sh3eb/init.c 1.1.8.3
gnu/usr.bin/gdb6/arch/sh3eb/nm.h 1.1.8.2
gnu/usr.bin/gdb6/arch/sh3eb/tm.h 1.1.8.2
gnu/usr.bin/gdb6/arch/sh3eb/version.c 1.1.8.2
gnu/usr.bin/gdb6/arch/sh3el/config.h 1.2.2.2
gnu/usr.bin/gdb6/arch/sh3el/defs.mk 1.2.8.3
gnu/usr.bin/gdb6/arch/sh3el/init.c 1.1.8.3
gnu/usr.bin/gdb6/arch/sh3el/nm.h 1.1.8.2
gnu/usr.bin/gdb6/arch/sh3el/tm.h 1.1.8.2
gnu/usr.bin/gdb6/arch/sh3el/version.c 1.1.8.2
gnu/usr.bin/gdb6/arch/sparc/defs.mk 1.2.6.1
gnu/usr.bin/gdb6/arch/sparc/init.c 1.1.6.1
gnu/usr.bin/gdb6/arch/sparc64/defs.mk 1.2.6.1
gnu/usr.bin/gdb6/arch/sparc64/init.c 1.1.6.1
gnu/usr.bin/gdb6/arch/vax/config.h 1.1.6.2
gnu/usr.bin/gdb6/arch/vax/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/arch/vax/init.c 1.1.6.2
gnu/usr.bin/gdb6/arch/vax/tm.h 1.1.6.2
gnu/usr.bin/gdb6/arch/vax/version.c 1.1.6.2
gnu/usr.bin/gdb6/arch/x86_64/defs.mk 1.2.6.1
gnu/usr.bin/gdb6/arch/x86_64/init.c 1.1.6.1
gnu/usr.bin/gdb6/bfd/arch/armeb/bfd.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/armeb/bfdver.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/armeb/config.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/armeb/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/m68000/bfd.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/m68000/bfdver.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/m68000/config.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/m68000/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/mipsel/bfd.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/mipsel/bfdver.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/mipsel/config.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/mipsel/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/sh3eb/bfd.h 1.1.8.3
gnu/usr.bin/gdb6/bfd/arch/sh3eb/bfdver.h 1.1.8.2
gnu/usr.bin/gdb6/bfd/arch/sh3eb/config.h 1.1.8.2
gnu/usr.bin/gdb6/bfd/arch/sh3eb/defs.mk 1.1.8.3
gnu/usr.bin/gdb6/bfd/arch/sh3el/bfd.h 1.1.8.3
gnu/usr.bin/gdb6/bfd/arch/sh3el/bfdver.h 1.1.8.2
gnu/usr.bin/gdb6/bfd/arch/sh3el/config.h 1.1.8.2
gnu/usr.bin/gdb6/bfd/arch/sh3el/defs.mk 1.1.8.3
gnu/usr.bin/gdb6/bfd/arch/vax/bfd.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/vax/bfdver.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/vax/config.h 1.1.6.2
gnu/usr.bin/gdb6/bfd/arch/vax/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/gdb/Makefile 1.5.2.1.2.2
gnu/usr.bin/gdb6/gdbtui/Makefile 1.2.6.1
gnu/usr.bin/gdb6/libiberty/arch/armeb/config.h 1.1.6.2
gnu/usr.bin/gdb6/libiberty/arch/armeb/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/libiberty/arch/m68000/config.h 1.1.6.2
gnu/usr.bin/gdb6/libiberty/arch/m68000/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/libiberty/arch/mipsel/config.h 1.1.6.2
gnu/usr.bin/gdb6/libiberty/arch/mipsel/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/libiberty/arch/sh3eb/config.h 1.1.8.2
gnu/usr.bin/gdb6/libiberty/arch/sh3eb/defs.mk 1.1.8.2
gnu/usr.bin/gdb6/libiberty/arch/sh3el/config.h 1.1.8.2
gnu/usr.bin/gdb6/libiberty/arch/sh3el/defs.mk 1.1.8.2
gnu/usr.bin/gdb6/libiberty/arch/vax/config.h 1.1.6.2
gnu/usr.bin/gdb6/libiberty/arch/vax/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/opcodes/arch/armeb/config.h 1.1.6.2
gnu/usr.bin/gdb6/opcodes/arch/armeb/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/opcodes/arch/m68000/config.h 1.1.6.2
gnu/usr.bin/gdb6/opcodes/arch/m68000/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/opcodes/arch/mipsel/config.h 1.1.6.2
gnu/usr.bin/gdb6/opcodes/arch/mipsel/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/opcodes/arch/sh3eb/config.h 1.1.8.2
gnu/usr.bin/gdb6/opcodes/arch/sh3eb/defs.mk 1.1.8.3
gnu/usr.bin/gdb6/opcodes/arch/sh3el/config.h 1.1.8.2
gnu/usr.bin/gdb6/opcodes/arch/sh3el/defs.mk 1.1.8.3
gnu/usr.bin/gdb6/opcodes/arch/vax/config.h 1.1.6.2
gnu/usr.bin/gdb6/opcodes/arch/vax/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/readline/arch/armeb/config.h 1.1.6.2
gnu/usr.bin/gdb6/readline/arch/armeb/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/readline/arch/m68000/config.h 1.1.6.2
gnu/usr.bin/gdb6/readline/arch/m68000/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/readline/arch/mipsel/config.h 1.1.6.2
gnu/usr.bin/gdb6/readline/arch/mipsel/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/readline/arch/sh3eb/config.h 1.1.8.2
gnu/usr.bin/gdb6/readline/arch/sh3eb/defs.mk 1.1.8.2
gnu/usr.bin/gdb6/readline/arch/sh3el/config.h 1.1.8.2
gnu/usr.bin/gdb6/readline/arch/sh3el/defs.mk 1.1.8.2
gnu/usr.bin/gdb6/readline/arch/vax/config.h 1.1.6.2
gnu/usr.bin/gdb6/readline/arch/vax/defs.mk 1.1.6.2
gnu/usr.bin/gdb6/sim/arch/mipseb/cconfig.h 1.1.2.1
gnu/usr.bin/gdb6/sim/arch/mipseb/config.h 1.1.2.1
gnu/usr.bin/gdb6/sim/arch/mipseb/defs.mk 1.1.2.1
gnu/usr.bin/gdb6/sim/arch/mipsel/cconfig.h 1.1.2.1
gnu/usr.bin/gdb6/sim/arch/mipsel/config.h 1.1.2.1
gnu/usr.bin/gdb6/sim/arch/mipsel/defs.mk 1.1.2.1
lib/libkvm/kvm_sparc64.c 1.10.18.2
lib/libpthread/pthread.c 1.48.6.4
lib/libpthread/pthread_barrier.c 1.6.18.1
lib/libpthread/pthread_cond.c 1.18.12.2
lib/libpthread/pthread_debug.h 1.8.18.1
lib/libpthread/pthread_int.h 1.34.4.5
lib/libpthread/pthread_lock.c 1.14.6.1
lib/libpthread/pthread_mutex.c 1.22.4.2
lib/libpthread/pthread_run.c 1.18.12.4
lib/libpthread/pthread_rwlock.c 1.13.6.2
lib/libpthread/pthread_sa.c 1.37.6.5
lib/libpthread/pthread_sig.c 1.47.4.8
lib/libpthread/pthread_sleep.c 1.7.6.2
lib/libpthread/sem.c 1.9.6.2
lib/libpthread/arch/sh3/pthread_md.h 1.3.6.1
regress/lib/libpthread/resolv/Makefile 1.1.12.1
regress/lib/libpthread/sigrunning/Makefile 1.1.2.1
regress/lib/libpthread/sigrunning/sigrunning.c 1.1.2.1
share/mk/bsd.own.mk 1.489.4.3
sys/arch/amd64/amd64/locore.S 1.18.14.1
sys/arch/amd64/amd64/machdep.c 1.44.2.3.2.1
sys/arch/amd64/conf/kern.ldscript 1.1.70.1
sys/arch/cats/conf/Makefile.cats.inc 1.17.30.1
sys/arch/shark/conf/Makefile.shark.inc 1.6.30.1
sys/arch/sparc64/conf/kern.ldscript 1.7.26.2
sys/arch/sparc64/conf/kern32.ldscript 1.6.26.2
sys/arch/sparc64/include/kcore.h 1.4.92.2
sys/arch/sparc64/sparc64/locore.s 1.232.4.4
sys/arch/sparc64/sparc64/machdep.c 1.193.4.3
sys/arch/sparc64/sparc64/pmap.c 1.184.2.1.2.4
sys/conf/newvers.sh 1.42.26.2
sys/kern/kern_sa.c 1.87.4.11
sys/kern/kern_synch.c 1.173.4.2
sys/sys/savar.h 1.20.10.2
tools/gdb/Makefile 1.9.4.1
tools/gdb/mknative-gdb 1.1.6.1

pullup the wrstuden-fixsa CVS branch to netbsd-4:
toolchain/35540 - GDB 6 support for pthreads.
port-sparc64/37534 - ktrace firefox gives
kernel trap 30: data access expection
GDB changes:
- delete gdb53
- enable gdb6 on all architectures
- add support for amd64 crash dumps
- add support for sparc64 crash dumps
- add support for /proc pid to executable filename for all archs
- enable thread support for all architectures
- add a note section to kernels to all platforms
- support detection/unwinding of signals for most architectures.
- Fix PTHREAD_UCONTEXT_TO_REG / PTHREAD_REG_TO_UCONTEXT on sh3.
- Apply fix from binutils-current so that sparc gdb can be cross built
on a 64bit host.
SA/pthread changes:
Pre-allocate memory needed for event delivery. Eliminates dropped
interrupts under load.
Deliver intra-process signals to running threads
Eliminate some deadlock scenarios
Fix intra-process signal delivery when delivering to a thread waiting
for signals. Makes afs work again!
 1.28.2.4  10-Sep-2007  skrll Sync with HEAD.
 1.28.2.3  03-Sep-2007  skrll Sync with HEAD.
 1.28.2.2  15-Aug-2007  skrll Sync with HEAD.
 1.28.2.1  18-Jul-2007  skrll Initial work on provided correctly aligned __cpu_simple_lock_t for hppa
and first attempt at adapting i386 to the changes.

More to come.
 1.29.2.2  04-Aug-2007  ad Some significant performance improvements, and a fix for a race with pthread
detach/join.

- Make mutex acquire spin for a short time, as done with spinlocks.
- Make the number of spins controllable with the env var PTHREAD_NSPINS.
- Reduce the amount of time that libpthread internal spinlocks are held.
- Rely more on the barrier effects of park/unpark to avoid taking spinlocks.
- Simplify the locking around pthreads and the global queues.
- Align per-thread sync data on a 128 byte boundary.
- Offset thread stacks by a small amount to try and reduce cache thrash.
 1.29.2.1  04-Aug-2007  ad file pthread_mutex.c was added on branch matt-mips64 on 2007-08-04 13:37:50 +0000
 1.31.2.3  23-Mar-2008  matt sync with HEAD
 1.31.2.2  09-Jan-2008  matt sync with HEAD
 1.31.2.1  06-Nov-2007  matt sync with HEAD
 1.45.2.1  24-Mar-2008  keiichi sync with head.
 1.47.2.2  04-Jun-2008  yamt sync with head
 1.47.2.1  18-May-2008  yamt sync with head.
 1.48.2.2  18-Sep-2008  wrstuden Sync with wrstuden-revivesa-base-2.
 1.48.2.1  23-Jun-2008  wrstuden Sync w/ -current. 34 merge conflicts to follow.
 1.51.22.2  20-Feb-2014  sborrill Pull up the following revisions(s) (requested by prlw1 in ticket #1029):
lib/libpthread/pthread_cond.c: revision 1.62
lib/libpthread/pthread_mutex.c: revision 1.57,1.59

Partial fix for thread deadlock commonly observed with named.
Also address PR/44756.
 1.51.22.1  29-Apr-2013  riz Pull up following revision(s) (requested by manu in ticket #869):
lib/libpthread/pthread_rwlock.c: revision 1.33
lib/libc/include/reentrant.h: revision 1.16
lib/libpthread/pthread_cond.c: revision 1.59
lib/libpthread/pthread_misc.c: revision 1.15
lib/libc/thread-stub/thread-stub.c: revision 1.23
lib/libpthread/pthread_cancelstub.c: revision 1.38
lib/libpthread/pthread_specific.c: revision 1.26
lib/libpthread/pthread_mutex.c: revision 1.56
lib/libpthread/pthread_tsd.c: revision 1.11
lib/libpthread/Makefile: revision 1.80
lib/libpthread/pthread.c: revision 1.143
lib/libpthread/pthread_int.h: revision 1.89
- Allow libpthread to be dlopened again, by providing libc stubs to
libpthread.
- Fail if the dlopened libpthread does pthread_create(). From manu@
- Discussed at length in the mailing lists; approved by core@
- This was chosen as the least intrusive patch that will provide
the necessary functionality.
XXX: pullup to 6
 1.51.6.2  02-Aug-2008  matt Change pthread_mutex_t to use the amount of space as and be congruent to
the version used in the SA version of pthreads. This preserves binary
compatibility between both versions of the library.
 1.51.6.1  02-Aug-2008  matt file pthread_mutex.c was added on branch christos-time_t on 2008-08-02 19:46:31 +0000
 1.51.4.1  20-Feb-2014  sborrill Pull up the following revisions(s) (requested by prlw1 in ticket #1898):
lib/libpthread/pthread_cond.c: revision 1.62
lib/libpthread/pthread_mutex.c: revision 1.57,1.59

Partial fix for thread deadlock commonly observed with named.
Also address PR/44756.
 1.51.2.3  22-May-2014  yamt sync with head.

for a reference, the tree before this commit was tagged
as yamt-pagecache-tag8.

this commit was splitted into small chunks to avoid
a limitation of cvs. ("Protocol error: too many arguments")
 1.51.2.2  30-Oct-2012  yamt sync with head
 1.51.2.1  17-Apr-2012  yamt sync with head
 1.54.2.2  20-Aug-2014  tls Rebase to HEAD as of a few days ago.
 1.54.2.1  23-Jun-2013  tls resync from head
 1.60.2.2  04-Nov-2016  pgoyette Sync with HEAD
 1.60.2.1  26-Jul-2016  pgoyette Sync with HEAD
 1.64.4.2  08-Apr-2020  martin Merge changes from current as of 20200406
 1.64.4.1  10-Jun-2019  christos Sync with HEAD
 1.65.2.1  26-Jan-2020  martin Pull up following revision(s) (requested by ad in ticket #647):

lib/libpthread/pthread_rwlock.c: revision 1.37 (patch)
lib/libpthread/pthread_misc.c: revision 1.16
lib/libpthread/pthread.c: revision 1.154
lib/libpthread/pthread_int.h: revision 1.98
lib/libpthread/pthread_cond.c: revision 1.66
lib/libpthread/pthread_mutex.c: revision 1.66

Rip out some very ambitious optimisations around pthread_mutex that are
don't buy much. This stuff is hard enough to get right in the kernel let
alone userspace, and I don't trust that it's right.

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