- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

Fix known issues which blow up the process after dlopen("libthr.so")
(or loading a dso linked to libthr.so into process which was not
linked against threading library).

MFC r276630:
Remove interposing, fix malloc, reinstall signal handlers wrappers on
libthr load.

MFC r276681:
Avoid calling internal libc function through PLT or accessing data
though GOT.

MFC r277032:
Reduce the size of the interposing table and amount of
cancellation-handling code in the libthr.

MFC note:
r276646 ("do not erronously export 'openat' symbol from rtld") is not
applicable to stable/10 yet, since PATHFDS support was not merged.

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

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

Add accept4() system call.

The accept4() function, compared to accept(), allows setting the new file
descriptor atomically close-on-exec and explicitly controlling the
non-blocking status on the new socket. (Note that the latter point means
that accept() is not equivalent to any form of accept4().)

The linuxulator's accept4 implementation leaves a race window where the new
file descriptor is not close-on-exec because it calls sys_accept(). This
implementation leaves no such race window (by using falloc() flags). The
linuxulator could be fixed and simplified by using the new code.

Like accept(), accept4() is async-signal-safe, a cancellation point and
permitted in capability mode.

Introduce a non-portable function pthread_getthreadid_np(3) to retrieve
calling thread's unique integral ID, which is similar to AIX function of
the same name. Bump __FreeBSD_version to note its introduction.

Reviewed by: kib

Implement the __pthread_map_stacks_exec() for libthr.

Stack creation code is changed to call _rtld_get_stack_prot() to get
the stack protection right. There is a race where thread is created
during dlopen() of dso that requires executable stacks. Then,
_rtld_get_stack_prot() may return PROT_READ | PROT_WRITE, but thread
is still not linked into the thread list. In this case, the callback
misses the thread stack, and rechecks the required protection
afterward.

Reviewed by: davidxu

Revert revision 214007, I realized that MySQL wants to resolve
a silly rwlock deadlock problem, the deadlock is caused by writer
waiters, if a thread has already locked a reader lock, and wants to
acquire another reader lock, it will be blocked by writer waiters,
but we had already fixed it years ago.

sort function name.

Add pthread_rwlockattr_setkind_np and pthread_rwlockattr_getkind_np, the
functions set or get pthread_rwlock type, current supported types are:
PTHREAD_RWLOCK_PREFER_READER_NP,
PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP,
PTHREAD_RWLOCK_PREFER_WRITER_NP,
default is PTHREAD_RWLOCK_PREFER_WRITER_NONCECURSIVE_NP, this maintains
binary compatible with old code.

To support stack unwinding for cancellation points, add -fexceptions flag
for them, two functions _pthread_cancel_enter and _pthread_cancel_leave
are added to let thread enter and leave a cancellation point, it also
makes it possible that other functions can be cancellation points in
libraries without having to be rewritten in libthr.

Update symbol.

Add wrapper for setcontext() and swapcontext(), the wrappers
unblock SIGCANCEL which is needed by thread cancellation.

On shared object unload, in __cxa_finalize, call and clear all installed
atexit and __cxa_atexit handlers that are either installed by unloaded
dso, or points to the functions provided by the dso.

Use _rtld_addr_phdr to locate segment information from the address of
private variable belonging to the dso, supplied by crtstuff.c. Provide
utility function __elf_phdr_match_addr to do the match of address against
dso executable segment.

Call back into libthr from __cxa_finalize using weak
__pthread_cxa_finalize symbol to remove any atfork handler which
function points into unloaded object.

The rtld needs private __pthread_cxa_finalize symbol to not require
resolution of the weak undefined symbol at initialization time. This
cannot work, since rtld is relocated before sym_zero is set up.

Idea by: kan
Reviewed by: kan (previous version)
MFC after: 3 weeks

Remove extra new semaphore stubs, because libc already has them, and
ld can find the newest version which is default.

Poked by: kan@

Use umtx to implement process sharable semaphore, to make this work,
now type sema_t is a structure which can be put in a shared memory area,
and multiple processes can operate it concurrently.
User can either use mmap(MAP_SHARED) + sem_init(pshared=1) or use sem_open()
to initialize a shared semaphore.
Named semaphore uses file system and is located in /tmp directory, and its
file name is prefixed with 'SEMD', so now it is chroot or jail friendly.
In simplist cases, both for named and un-named semaphore, userland code
does not have to enter kernel to reduce/increase semaphore's count.
The semaphore is designed to be crash-safe, it means even if an application
is crashed in the middle of operating semaphore, the semaphore state is
still safely recovered by later use, there is no waiter counter maintained
by userland code.
The main semaphore code is in libc and libthr only has some necessary stubs,
this makes it possible that a non-threaded application can use semaphore
without linking to thread library.
Old semaphore implementation is kept libc to maintain binary compatibility.
The kernel ksem API is no longer used in the new implemenation.

Discussed on: threads@

Make openat(2) a cancellation point.

This is required by POSIX and matches open(2).

Reviewed by: kib, jhb
MFC after: 1 month

Make pthread_cleanup_push() and pthread_cleanup_pop() as a pair of macros,
use stack space to keep cleanup information, this eliminates overhead of
calling malloc() and free() in thread library.

Discussed on: thread@

Add POSIX pthread API pthread_getcpuclockid() to get a thread's cpu
time clock id.

Add more cpu affinity function's symbols.

Implement functions pthread_getaffinity_np and pthread_setaffinity_np to
get and set thread's cpu affinity mask.

Yet another pointy hat: when I zapped FBSDprivate_1.1, I forgot to move
its contents to FBSDprivate_1.0.

Convert pthread.map to the format expected by version_gen.awk, and modify
the Makefile accordingly; libthr now explicitly uses libc's Versions.def.

MFC after: 2 weeks

Remove incorrectly added FBSDprivate_1.1 namespace, and move symbols which
are new in FreeBSD 8 to the appropriate namespace.

Per discussion on -threads, rename _islocked_np() to _isowned_np().

Add pthread_mutex_islocked_np(), a cheap way to verify that a mutex is
locked. This is intended primarily to support the userland equivalent
of the various *_ASSERT_LOCKED() macros we have in the kernel.

MFC after: 2 weeks

Remove vfork() overloading, it is no longer needed.

1. Add function pthread_mutex_setspinloops_np to turn a mutex's spin
loop count.
2. Add function pthread_mutex_setyieldloops_np to turn a mutex's yield
loop count.
3. Make environment variables PTHREAD_SPINLOOPS and PTHREAD_YIELDLOOPS
to be only used for turnning PTHREAD_MUTEX_ADAPTIVE_NP mutex.

Add _pthread_mutex_init_calloc_cb() to libthr and libkse, so that malloc(3)
(part of libc) can use pthreads mutexes without causing infinite recursion
during initialization.

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.

Use C comments since we now preprocess these files with CPP.

1. Don't override underscore version of aio_suspend(), system(),
wait(), waitpid() and usleep(), they are internal versions and
should not be cancellation points.
2. Make wait3() as a cancellation point.
3. Move raise() and pause() into file thr_sig.c.
4. Add functions _sigsuspend, _sigwait, _sigtimedwait and _sigwaitinfo,
remove SIGCANCEL bit in wait-set for those functions, the signal is
used internally to implement thread cancellation.

Add symbol versions: FBSD_1.0 and FBSDprivate.

WARNS level 4 cleanup.

Remove mqueue and timer, now they are in librt.

1. Add SIGEV_THREAD notification for mq_notify.
2. Reuse current timer code and abstract some common code to
to support both timer and mqueue.

Follow the mistake in libpthread, the first version name in libpthread
is LIBTHREAD_1_0, but really it should be LIBPTHREAD_1_0.
Fix it so libmap.conf works again (it was broken by recent versioning
code in rtld_elf).

Add code to handle timer_delete(). The timer wrapper code is completely
rewritten, now timers created with same sigev_notify_attributes will
run in same thread, this allows user to organize which timers can
run in same thread to save some thread resource.

Add timer_create wrapper.

Put pthread_condattr_init sorted order.

Export following functions:
_pthread_mutexattr_getpshared
_pthread_mutexattr_setpshared
pthread_condattr_getpshared
pthread_condattr_setpshared
pthread_mutexattr_getpshared
pthread_mutexattr_setpshared

Sort function names.

Add function pthread_timedjoin_np, the function is similar with pthread_join
except the function will return ETIMEDOUT if target thread does not exit
before specified absolute time passes.

Add usleep to the map files.

Noticed by: davidxu

Add debugger event reporting support, current only TD_CREATE and TD_DEATH
events are reported.

Export pthread_condattr_getclock, pthread_condattr_setclock.

Import my recent 1:1 threading working. some features improved includes:
1. fast simple type mutex.
2. __thread tls works.
3. asynchronous cancellation works ( using signal ).
4. thread synchronization is fully based on umtx, mainly, condition
variable and other synchronization objects were rewritten by using
umtx directly. those objects can be shared between processes via
shared memory, it has to change ABI which does not happen yet.
5. default stack size is increased to 1M on 32 bits platform, 2M for
64 bits platform.
As the result, some mysql super-smack benchmarks show performance is
improved massivly.

Okayed by: jeff, mtm, rwatson, scottl