libc, libthr: coordinate stubs for pthread_{suspend,resume}_all_np

If libthr isn't linked into the process, then we don't have any pthreads
to worry about and our stubs can just return success -- th

libc, libthr: coordinate stubs for pthread_{suspend,resume}_all_np

If libthr isn't linked into the process, then we don't have any pthreads
to worry about and our stubs can just return success -- there are none
to suspend/resume.

Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D47350

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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/

Merge ^/head r325999 through r326131.

General further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier f

General further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

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.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

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Do not leak THR_FLAGS_SUSPENDED from the previous suspend/resume
cycle. The flag currently is cleared by the resumed thread. If next
suspend request comes before the thread was able to clean the fl

Do not leak THR_FLAGS_SUSPENDED from the previous suspend/resume
cycle. The flag currently is cleared by the resumed thread. If next
suspend request comes before the thread was able to clean the flag, in
which case suspender skip the thread.

Instead, clear the THR_FLAGS_SUSPEND flag in resume_common(), we do
not care how much code was executed in the resumed thread when the
pthread_resume_*np(s) functions returned.

PR: 209233
Reported by: Lawrence Esswood <le277@cam.ac.uk>
MFC after: 1 week

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MFH

Sponsored by: The FreeBSD Foundation

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

Sponsored by: The FreeBSD Foundation

MFC @ r241285

IFC @ r242684

Sync from head

Merge head r233826 through r240095.

In suspend_common(), don't wait for a thread which is in creation, because
pthread_suspend_all_np() may have already suspended its parent thread.
Add locking code in pthread_suspend_all_np() to only

In suspend_common(), don't wait for a thread which is in creation, because
pthread_suspend_all_np() may have already suspended its parent thread.
Add locking code in pthread_suspend_all_np() to only allow one thread
to suspend other threads, this eliminates a deadlock where two or more
threads try to suspend each others.

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Convert thread list lock from mutex to rwlock.

Use UMTX_OP_WAIT_UINT_PRIVATE and UMTX_OP_WAKE_PRIVATE to save
time in kernel(avoid VM lookup).

Remove 3rd clause, renumber, ok per email

WARNS level 4 cleanup.

Refine thread suspension code, now thread suspension is a blockable
operation, the caller is blocked util target threads are really
suspended, also avoid suspending a thread when it is holding a
crit

Refine thread suspension code, now thread suspension is a blockable
operation, the caller is blocked util target threads are really
suspended, also avoid suspending a thread when it is holding a
critical lock.
Fix a bug in _thr_ref_delete which tests a never set flag.

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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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Make libthr async-signal-safe without costly signal masking. The guidlines I
followed are: Only 3 functions (pthread_cancel, pthread_setcancelstate,
pthread_setcanceltype) are required to be async-si

Make libthr async-signal-safe without costly signal masking. The guidlines I
followed are: Only 3 functions (pthread_cancel, pthread_setcancelstate,
pthread_setcanceltype) are required to be async-signal-safe by POSIX. None of
the rest of the pthread api is required to be async-signal-safe. This means
that only the three mentioned functions are safe to use from inside
signal handlers.
However, there are certain system/libc calls that are
cancellation points that a caller may call from within a signal handler,
and since they are cancellation points calls have to be made into libthr
to test for cancellation and exit the thread if necessary. So, the
cancellation test and thread exit code paths must be async-signal-safe
as well. A summary of the changes follows:

o Almost all of the code paths that masked signals, as well as locking the
pthread structure now lock only the pthread structure.
o Signals are masked (and left that way) as soon as a thread enters
pthread_exit().
o The active and dead threads locks now explicitly require that signals
are masked.
o Access to the isdead field of the pthread structure is protected by both
the active and dead list locks for writing. Either one is sufficient for
reading.
o The thread state and type fields have been combined into one three-state
switch to make it easier to read without requiring a lock. It doesn't need
a lock for writing (and therefore for reading either) because only the
current thread can write to it and it is an integer value.
o The thread state field of the pthread structure has been eliminated. It
was an unnecessary field that mostly duplicated the flags field, but
required additional locking that would make a lot more code paths require
signal masking. Any truly unique values (such as PS_DEAD) have been
reborn as separate members of the pthread structure.
o Since the mutex and condvar pthread functions are not async-signal-safe
there is no need to muck about with the wait queues when handling
a signal ...
o ... which also removes the need for wrapping signal handlers and sigaction(2).
o The condvar and mutex async-cancellation code had to be revised as a result
of some of these changes, which resulted in semi-unrelated changes which
would have been difficult to work on as a separate commit, so they are
included as well.

The only part of the changes I am worried about is related to locking for
the pthread joining fields. But, I will take a closer look at them once this
mega-patch is committed.

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Stop using signals for synchronizing threads. The performance penalty
was too much.

Doh! Lock the thread passed in by the caller, not the current thread.

Remove uses of GIANT_LOCK and replace with appropriate thread
and thread list locks.

Make WARNS2 clean. The fixes mostly included:
o removed unused variables
o explicit inclusion of header files
o prototypes for externally defined functions

Approved by: re/blanket libthr

- Define curthread as _get_curthread() and remove all direct calls to
_get_curthread(). This is similar to the kernel's curthread. Doing
this saves stack overhead and is more convenient to th

- Define curthread as _get_curthread() and remove all direct calls to
_get_curthread(). This is similar to the kernel's curthread. Doing
this saves stack overhead and is more convenient to the programmer.
- Pass the pointer to the newly created thread to _thread_init().
- Remove _get_curthread_slow().

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