libthr: add pthread_sigqueue(3)

PR: 278459
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D44867

Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

Reduce code duplication in machine/_types.h

Many of these typedefs are the same across all architectures or can
be set based on an architecture-independent compiler-provided macro
(e.g. __SIZEOF_SIZE_T__). These macros have been available since GCC 4.6
and Clang sometime before 3.0 (godbolt.org does not have any older clang
versions installed).

I originally considered using the compiler-provided `__FOO_TYPE__` directly.
However, in order to do so we have to check that those match the previous
typedef exactly (not just that they have the same size) since any change
would be an ABI break. For example, changing `long` to `long long` results
in different C++ name mangling. Additionally, Clang and GCC disagree on
the underlying type for some of (u)int*_fast_t types, so this change
only moves the definitions that are identical across all architectures
and does not touch those types.

This de-deduplication will allow us to have a smaller diff downstream in
CheriBSD: we only have to only change the (u)intptr_t definition in
sys/_types.h in CheriBSD instead of having to change machine/_types.h for
all CHERI-enabled architectures (currently RISC-V, AArch64 and MIPS).

Reviewed By: imp, kib
Differential Revision: https://reviews.freebsd.org/D29895

Add pthread_getname_np() and pthread_setname_np() aliases for
pthread_get_name_np() and pthread_set_name_np().

This re-applies r361770 after compatibility fixes.

Reviewed by: antoine, jkim, markj
Tested by: antoine (exp-run)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D25117

POSIX compliance improvements in the pthread(3) functions.

This basically adds makes use of the C99 restrict keyword, and also
adds some 'const's to four threading functions: pthread_mutexattr_gettype(),
pthread_mutexattr_getprioceiling(), pthread_mutexattr_getprotocol(), and
pthread_mutex_getprioceiling. The changes are in accordance to POSIX/SUSv4-2018.

Hinted by: DragonFlyBSD

Relnotes: yes
MFC after: 1 month
Differential Revision: D16722

pthread.h: minor indentation cleanups.

No functional change.

X-MFC with: r331969

pthread.h: drop nullability attributes.

These have been found to be practically useless. We were actually
following the Android bionic library and had some interest in replicating
the same warnings and behaviour but Android has since removed them.

We are still keeping some uses of nullability attributes in other headers,
somewhat in line with Apple's libc.

MFC after: 1 week
Hinted by: bionic (git 3f66e74b903905e763e104396aff52a81718cfde)

include: General 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.

Small inclusion guard comment fix.

Make use of clang nullability attributes.

Replace uses of the GCC __nonnull__ attribute with the clang nullability
qualifiers. The replacement should be transparent for clang developers as
the new qualifiers will produce the same warnings and will be useful for
static checkers but will not cause aggressive optimizations.

GCC will not produce such warnings and developers will have to use
upgraded GCC ports built with the system headers from r312538.

Hinted by: Apple's Libc-1158.20.4, Bionic libc
MFC after: 11.1 Release

Differential Revision: https://reviews.freebsd.org/D9004

Remove some uses of the GCC __nonnull() attribute.

While the checks are considered useful, the attribute does dangerous
optimizations, removing NULL checks where they can be needed. Remove the
uses of this attribute introduced in r281130: the changes were inspired on
Google's bionic where this attribute is not used anymore.

The __nonnull() attribute will be deprecrated from our headers and
replaced with the Clang _Nonnull qualifier in the future.

MFC after: 3 days

Add implementation of robust mutexes, hopefully close enough to the
intention of the POSIX IEEE Std 1003.1TM-2008/Cor 1-2013.

A robust mutex is guaranteed to be cleared by the system upon either
thread or process owner termination while the mutex is held. The next
mutex locker is then notified about inconsistent mutex state and can
execute (or abandon) corrective actions.

The patch mostly consists of small changes here and there, adding
neccessary checks for the inconsistent and abandoned conditions into
existing paths. Additionally, the thread exit handler was extended to
iterate over the userspace-maintained list of owned robust mutexes,
unlocking and marking as terminated each of them.

The list of owned robust mutexes cannot be maintained atomically
synchronous with the mutex lock state (it is possible in kernel, but
is too expensive). Instead, for the duration of lock or unlock
operation, the current mutex is remembered in a special slot that is
also checked by the kernel at thread termination.

Kernel must be aware about the per-thread location of the heads of
robust mutex lists and the current active mutex slot. When a thread
touches a robust mutex for the first time, a new umtx op syscall is
issued which informs about location of lists heads.

The umtx sleep queues for PP and PI mutexes are split between
non-robust and robust.

Somewhat unrelated changes in the patch:
1. Style.
2. The fix for proper tdfind() call use in umtxq_sleep_pi() for shared
pi mutexes.
3. Removal of the userspace struct pthread_mutex m_owner field.
4. The sysctl kern.ipc.umtx_vnode_persistent is added, which controls
the lifetime of the shared mutex associated with a vnode' page.

Reviewed by: jilles (previous version, supposedly the objection was fixed)
Discussed with: brooks, Martin Simmons <martin@lispworks.com> (some aspects)
Tested by: pho
Sponsored by: The FreeBSD Foundation

Implement process-shared locks support for libthr.so.3, without
breaking the ABI. Special value is stored in the lock pointer to
indicate shared lock, and offline page in the shared memory is
allocated to store the actual lock.

Reviewed by: vangyzen (previous version)
Discussed with: deischen, emaste, jhb, rwatson,
Martin Simmons <martin@lispworks.com>
Tested by: pho
Sponsored by: The FreeBSD Foundation

Make use of gcc attributes in some standard include headers.

The `nonnull' attribute specifies that some function parameters should be
non-null pointers. This is very useful as it helps the compiler generate
warnings on suspicious code and can also enable some small optimizations.

Also start using 'alloc_size' attribute in the allocator functions.

This is an initial step to better integrate our libc with the compiler:
these attributes are fully supported by clang and they are also useful
for the static analyzer.

Note that due to some bogus internal procedure in the way gcc ports
are built they may require updating if they were built before r280801.

Relnotes: yes
Hinted by: Android's bionic libc
Differential Revision: https://reviews.freebsd.org/D2107

Clean some spaces vs tabs.

No, this file doesn't conform with KNF at all.

Temporarily revert 280458.

GCC is still carries an old version of cdefs.h which doesn't
accept multiple parameters for the nonnull attribute.

Since this issue probably affects many ports in the tree
we will revert it for now until gcc gets fixed.

Introduce nonnull attributes in the signal and pthread headers.

The `nonnull' attribute specifies that some function parameters should be
non-null pointers. This is very useful as it helps the compiler generate
warnings on suspicious code and can also enable some small optimizations.
In clang this is also useful for the static analyzer.

While we could go on defining this all over the tree, it only
makes sense to annotate a subset of critical functions.

Hinted by: Android's bionic libc
Differential Revision: https://reviews.freebsd.org/D2101

Add lock annotations to the header files of our threading libraries.

This change extends all of the functions present in the <pthread.h> and
<threads.h> headers to have lock annotations. This will allow Clang to
warn about the following:

- Locking a function twice,
- Unlocking a function without a mutex being locked,
- Forgetting to unlock a mutex before returning,
- Destroying or reinitializing a mutex that is currenty locked,
- Using an unlocked mutex in combination with a condition variable.

Enabling these annotations already allowed me to catch a bug in one of
our userspace tools (r270749).

Add a dummy statement to the beginning of the pthread_cleanup_pop() macro
to allow a call of the macro to be labelled as in:

label:
pthread_cleanup_pop();

Reviewed by: imp
MFC after: 3 days

Remove leftover for r214093.

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

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.

In current code, statically initialized and destroyed object have
same null value, the code can not distinguish between them, to
fix the problem, now a destroyed object is assigned to a non-null
value, and it will be rejected by some pthread functions.
PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP is changed to number 1, so that
adaptive mutex can be statically initialized correctly.

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

Fix the visibility of several prototypes. Also move pthread_kill() and
pthread_sigmask() to signal.h. In principle, this shouldn't break anything,
since they're already in signal.h on other systems, and the FreeBSD
manpage says that both pthread.h and signal.h need to be included to
get these functions.

Add a hack to declare pthread_t in the P1003.1-2008 namespace
in signal.h.

- Import the HEAD csup code which is the basis for the cvsmode work.

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 a new "non-portable" mutex type, PTHREAD_MUTEX_ADAPTIVE_NP. This
is also implemented in glibc and is used by a number of existing
applications (mysql, firefox, etc).

This mutex type is a default mutex with the additional property that
it spins briefly when attempting to acquire a contested lock, doing
trylock operations in userland before entering the kernel to block if
eventually unsuccessful.

The expectation is that applications requesting this mutex type know
that the mutex is likely to be only held for very brief periods, so it
is faster to spin in userland and probably succeed in acquiring the
mutex, than to enter the kernel and sleep, only to be woken up almost
immediately. This can help significantly in certain cases when
pthread mutexes are heavily contended and held for brief durations
(such as mysql).

Spin up to 200 times before entering the kernel, which represents only
a few us on modern CPUs. No performance degradation was observed with
this value and it is sufficient to avoid a large performance drop in
mysql performance in the heavily contended pthread mutex case.

The libkse implementation is a NOP.

Reviewed by: jeff
MFC after: 3 days

Add prototype for following functions, plus tab fixes.
pthread_condattr_getpshared
pthread_condattr_setpshared
pthread_mutexattr_getpshared
pthread_mutexattr_setpshared

Improve POSIX conformance:
- Don't pollute the namespace by including <sys/types.h>, <sys/time.h>,
<sys/signal.h> and <limits.h>. Use __MINSIGSTKSZ and __ULONG_MAX from
<machine/_limits.h>, __sigset_t from <sys/_sigset.h> instead.
- Include <time.h> because POSIX says we have to.

PTHREAD_{DESTRUCTOR_ITERATIONS,KEYS_MAX,STACK_MIN,THREADS_MAX} should
eventually move to <limits.h> but are left here for now.

Discussed on: standards@, threads@

- Prefix MUTEX_TYPE_MAX with PTHREAD_ to avoid namespace pollution.
- Remove the macros MUTEX_TYPE_FAST and MUTEX_TYPE_COUNTING_FAST.

OK'ed by: deischen

Remove parameter names, the identifiers were in the user namespace.

According to:
http://www.opengroup.org/onlinepubs/009695399/basedefs/sys/types.h.html

#include <sys/types.h>
should include the definitions of pthread types.

PR: standards/78907
Reported by: Brooks Davis
Approved by: das (mentor)

Increase PTHREAD_STACK_MIN to MINSIGSTKSZ because thread libraries now use
makecontext which enforces a minimum stack size to be MINSIGSTKSZ.

Bug report: Bill Middleton <flashdict at gmail dot com>, BSD-sharp project.

Add pthread_condattr_getclock, pthread_condattr_setclock.

Fix typo, function name pthread_rwlock_timedrwlock should be
pthread_rwlock_timedwrlock.

Add the pthread_atfork() prototype.

Reviewed by: davidxu

Add code to support pthread spin lock.

Reviewed by: deischen

Add small piece of code to support pthread_rwlock_timedrdlock and
pthread_rwlock_timedrwlock.

Add code to support barrier synchronous object and implement
pthread_mutex_timedlock().

Reviewed by: deischen

Add stub implementations of pthread_[gs]etconcurrency to libc_r and
libthr. No changes were made to libpthread by request of deischen,
who will soon commit a real implementation for that library.

PR: standards/50848
Submitted by: Sergey A. Osokin <osa@freebsd.org.ru>
MFC after: 1 week

Add pthread_attr_getstack() and pthread_attr_setstack().

Submitted by: Craig Rodrigues <rodrigc@attbi.com>

In the absence of consensus as to implement stubs for these TSH-shaded
routines, remove their declarations. Even though rwlocks have the same
functions, XBDft does not shade those declarations so I am leaving them in.
(This is probably a bug in the Standard.)

Breath deep and take __P out of the system include files.

# This appears to not break X11, but I'm having problems compiling the
# glide part of the server with or without this patch, so I can't tell
# for sure.

Implement pthread_attr_[gs]etguardsize(). Non-default-size stacks used to
be malloc()ed, but they are now allocated using mmap(), just as the
default-size stacks are. A separate cache of stacks is kept for
non-default-size stacks.

Collaboration with: deischen

mark pthread_exit() as non-returning.

Requested by: Farooq Mela <fmela0@sm.socccd.cc.ca.us>

Remove prototypes for pthread_attr_[gs]etfloatstate(), which we don't
implement.

Fixed missing consts for function parameters, so that the code matches
the man page and POSIX.1. Fixed nearby misformatting. Fixed a missing
prototype.

Do not conditionalize function prototype definition for functions we
implement.

Noticed by: Thimble Smith <tim@mysql.com>
Approved by: jkh

Make sched_param parameter a const to comply with POSIX and SUSv2 specs.
This doesn't need to be applied to stable, because somehow -stable seems
to have gotten it right.

Reviewed by: jasone

Fix some minor POSIX/SUSv2 compliance nits.

PR: kern/11982

Move POSIX feature constants from pthread.h to unistd.h, as required by
1003.1c-1995.

Undefine _POSIX_THREAD_SAFE_FUNCTIONS, since we do not implement all of the
necessary interfaces. At least getgrgid_r(), getrnam_r(), getpwuid_r(),
getpwnam_r(), getc_unlocked(), getchar_unlocked(), putc_unlocked(),
and putchar_unlocked() are missing. Due to a likely typo in 1003.1c-1995,
we are not technically allowed to define _POSIX_THREADS without defining
_POSIX_THREAD_SAFE_FUNCTIONS, but either way we're non-compliant, so I'm
leaving _POSIX_THREADS defined.

PR: bin/8281

add pthread_cancel, obtained from OpenBSD.

eischen (Daniel Eischen) added wrappers to protect against cancled
threads orphaning internal resources.

the cancelability code is still a bit fuzzy but works for test
programs of my own, OpenBSD's and some examples from ORA's books.

add readdir_r to both libc and libc_r

add some 'const' attributes to function parameters

Reviewed by: eischen, jasone

$Id$ -> $FreeBSD$

Cleanups to the pthread header files.

Submitted by: Ralf S. Engelschall <rse@engelschall.com>
Reviewed by: John Birrell <jb@cimlogic.com.au>

Hide pthread cancellation routines behind #ifdef NOT_YET. They are
not currently supported. Also corrected the declaration for
pthread_testcancel which incorrectly returned int when POSIX and
SUSv2 both say it should be void.

Submitted by: Ralf S. Engelschall <rse@engelschall.com>
Reviewed by: John Birrell <jb@freebsd.org>

o Runnable threads are now maintained in priority queues. The
implementation requires two things:

1.) The priority queues must be protected during insertion
and removal of threads. Since the kernel scheduler
must modify the priority queues, a spinlock for
protection cannot be used. The functions
_thread_kern_sched_defer() and _thread_kern_sched_undefer()
were added to {un}defer kernel scheduler activation.

2.) A thread (active) priority change can be performed only
when the thread is removed from the priority queue. The
implementation uses a threads active priority when
inserting it into the queue.

A by-product is that thread switches are much faster. A
separate queue is used for waiting and/or blocked threads,
and it is searched at most 2 times in the kernel scheduler
when there are active threads. It should be possible to
reduce this to once by combining polling of threads waiting
on I/O with the loop that looks for timed out threads and
the minimum timeout value.

o Functions to defer kernel scheduler activation were added. These
are _thread_kern_sched_defer() and _thread_kern_sched_undefer()
and may be called recursively. These routines do not block the
scheduling signal, but latch its occurrence. The signal handler
will not call the kernel scheduler when the running thread has
deferred scheduling, but it will be called when running thread
undefers scheduling.

o Added support for _POSIX_THREAD_PRIORITY_SCHEDULING. All the
POSIX routines required by this should now be implemented.
One note, SCHED_OTHER, SCHED_FIFO, and SCHED_RR are required
to be defined by including pthread.h. These defines are currently
in sched.h. I modified pthread.h to include sched.h but don't
know if this is the proper thing to do.

o Added support for priority protection and inheritence mutexes.
This allows definition of _POSIX_THREAD_PRIO_PROTECT and
_POSIX_THREAD_PRIO_INHERIT.

o Added additional error checks required by POSIX for mutexes and
condition variables.

o Provided a wrapper for sigpending which is marked as a hidden
syscall.

o Added a non-portable function as a debugging aid to allow an
application to monitor thread context switches. An application
can install a routine that gets called everytime a thread
(explicitly created by the application) gets context switched.
The routine gets passed the pthread IDs of the threads that are
being switched in and out. I found this useful, but we can
get rid of it if you want.

Submitted by: Dan Eischen <eischen@vigrid.com>

Add support for pthread_mutexattr_settype(). As a side effect of
testing this, fix MUTEX_TYPE_COUNTING_FAST. Recursive locks now work.

Implement pthread read/write locks as defined by Version 2 of the Single
UNIX Specification.

As with our standard mutexes, process shared locks are not supported at
this time.

Add static initializer defines as specified by POSIX.

Changed pthread_detach to conform to POSIX, i.e. the single argument
provided is of type pthread_t instead of pthread_t *.

PR: 4320

Return EINVAL instead of ESRCH if attempting to detach an already
detached thread.

Fixed missing __P() to complete the K&R support in this header.

Comment out _POSIX_THREAD_PRIORITY_SCHEDULING since it's not supported
at this time.

Reviewed by: John Birrell <jb@cimlogic.com.au>

Submitted by: John Birrell
uthreads update from the author.

Moved pthread_mutexattr_default inside #ifndef PTHREAD_KERNEL now that
we use it in the uthreads implementation.
Moved enum pthread_mutextype here from libc_r/uthread/pthread_private.h.
Change prototype for pthread_getspecific().

Submitted by: John Birrell <cimaxp1!jb@werple.net.au>

Here are the diffs for libc_r to get it one step closer to P1003.1c
These make most of the thread/mutex/condvar structures opaque to the
user. There are three functions which have been renamed with _np
suffixes because they are extensions to P1003.1c (I did them for JAVA,
which needs to suspend/resume threads and also start threads suspended).

I've created a new header (pthread_np.h) for the non-POSIX stuff.

The egrep tags stuff in /usr/src/lib/libc_r/Makefile that I uncommented
doesn't work. I think its best to delete it. I don't think libc_r needs
tags anyway, 'cause most of the source is in libc which does have tags.

also:

Here's the first batch of man pages for the thread functions.
The diff to /usr/src/lib/libc_r/Makefile removes some stuff that was
inherited from /usr/src/lib/libc/Makefile that should only be done with
libc.

also:

I should have sent this diff with the pthread(3) man page.
It allows people to type

make -DWANT_LIBC_R world

to get libc_r built with the rest of the world. I put this in the
pthread(3) man page. The default is still not to build libc_r.


also:
The diff attached adds a pthread(3) man page to /usr/src/share/man/man3.
The idea is that without libc_r installed, this man page will give people
enough info to know that they have to build libc_r.

Submitted by: john birrel

Obtained from: uthread package

thrreads definitions