cosmopolitan/libc/intrin/pthread_spin_lock.c
Justine Tunney cee6871710
Make detached threads work better
This change adds a double linked list of threads, so that pthread_exit()
will know when it should call exit() from an orphaned child. This change
also improves ftrace and strace logging.
2022-11-09 03:58:57 -08:00

53 lines
2.7 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/intrin/atomic.h"
#include "libc/thread/thread.h"
#ifdef pthread_spin_lock
#undef pthread_spin_lock
#endif
/**
* Acquires spin lock, e.g.
*
* pthread_spinlock_t lock;
* pthread_spin_init(&lock, PTHREAD_PROCESS_PRIVATE);
* pthread_spin_lock(&lock);
* // do work...
* pthread_spin_unlock(&lock);
* pthread_spin_destroy(&lock);
*
* This function has undefined behavior when `spin` wasn't intialized,
* was destroyed, or if the lock's already held by the calling thread.
*
* @return 0 on success, or errno on error
* @see pthread_spin_trylock
* @see pthread_spin_unlock
* @see pthread_spin_init
*/
errno_t pthread_spin_lock(pthread_spinlock_t *spin) {
int x;
for (;;) {
x = atomic_exchange_explicit(&spin->_lock, 1, memory_order_acquire);
if (!x) break;
_unassert(x == 1);
}
return 0;
}