libthr: remove explicit sys/cdefs.h includes

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

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Avoid conflicts with libc symbols in libthr jump table.

In some corner cases of static linking and unexpected libraries order
on the linker command line, libc symbol might preempt the same libthr
sy

Avoid conflicts with libc symbols in libthr jump table.

In some corner cases of static linking and unexpected libraries order
on the linker command line, libc symbol might preempt the same libthr
symbol, in which case libthr jump table points back to libc causing
either infinite recursion or loop. Handle all of such symbols by
using private libthr names for them, ensuring that the right pointers
are installed into the table.

In collaboration with: arichardson
PR: 239475
Tested by: pho
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D21088

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lib: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
pr

lib: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

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Merge ^/head r303250 through r304235.

Remove empty initializer for the once facility. It was not needed
since r179417.

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

MFH

Sponsored by: The FreeBSD Foundation

Use __FBSDID() for .c files from lib/libthr/thread.

Sponsored by: The FreeBSD Foundation

Merge from head

Sponsored by: Gandi.net

Merge from head

Finish merging from head, messed up in previous attempt

Merge ^/head r287527 through r287679.

Merge r286744-r287584 from head.

Style. Use ANSI definition, wrap long lines, no initialization in
declaration for locals.

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

In the pthread_once(), if the initializer has already run, then the
calling thread is supposed to see accesses issued by the initializer.
This means that the read of the once_control->state variable

In the pthread_once(), if the initializer has already run, then the
calling thread is supposed to see accesses issued by the initializer.
This means that the read of the once_control->state variable should
have an acquire semantic. Use atomic_thread_fence_acq() when the
value read is ONCE_DONE, instead of straightforward atomic_load_acq(),
to only put a barrier when needed (*).

On the other hand, the updates of the once_control->state with the
intermediate progress state do not need to synchronize with other
state accesses, remove _acq suffix.

Reviewed by: alc (previous version)
Suggested by: alc (*)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

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r179417 introduced a bug into pthread_once(). Previously pthread_once()
used a global pthread_mutex_t for synchronization. r179417 replaced that
with an implementation that directly used atomic ins

r179417 introduced a bug into pthread_once(). Previously pthread_once()
used a global pthread_mutex_t for synchronization. r179417 replaced that
with an implementation that directly used atomic instructions and thr_*
syscalls to synchronize callers to pthread_once. However, calling
pthread_mutex_lock on the global mutex implicitly ensured that
_thr_check_init() had been called but with r179417 this was no longer
guaranteed. This meant that if you were unlucky enough to have your first
call into libthr be a call to pthread_once(), you would segfault when
trying to access the pointer returned by _get_curthread().

The fix is to explicitly call _thr_check_init() from pthread_once().

Reviewed by: davidxu
Approved by: emaste (mentor)
MFC after: 1 week

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Eliminate global mutex by using pthread_once's state field as
a semaphore.

Use macro THR_CLEANUP_PUSH/POP, they are cheaper than pthread_cleanup_push/pop.

Rework last change of pthread_once, create a function _thr_once_init to
reinitialize its internal locks.

After fork(), reinitialize internal locks for pthread_once().

Update copyright.

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 synchroni

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

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- Add libthr but don't hook it up to the regular build yet. This is an
adaptation of libc_r for the thr system call interface. This is beta
quality code.

Eliminate global mutex by using pthread_once's state field as
a semaphore.