mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-05 21:00:05 +00:00
1d2fc9b3c5
2000-01-03 Kaz Kylheku <kaz@ashi.footprints.net>
Redesigned how cancellation unblocks a thread from internal
cancellation points (sem_wait, pthread_join,
pthread_cond_{wait,timedwait}).
Cancellation won't eat a signal in any of these functions
(*required* by POSIX and Single Unix Spec!).
* condvar.c: spontaneous wakeup on pthread_cond_timedwait won't eat a
simultaneous condition variable signal (not required by POSIX
or Single Unix Spec, but nice).
* spinlock.c: __pthread_lock queues back any received restarts
that don't belong to it instead of assuming ownership of lock
upon any restart; fastlock can no longer be acquired by two threads
simultaneously.
* restart.h: restarts queue even on kernels that don't have
queued real time signals (2.0, early 2.1), thanks to atomic counter,
avoiding a rare race condition in pthread_cond_timedwait.
103 lines
3.1 KiB
C
103 lines
3.1 KiB
C
/* Linuxthreads - a simple clone()-based implementation of Posix */
|
|
/* threads for Linux. */
|
|
/* Copyright (C) 1998 Xavier Leroy (Xavier.Leroy@inria.fr) */
|
|
/* */
|
|
/* This program is free software; you can redistribute it and/or */
|
|
/* modify it under the terms of the GNU Library General Public License */
|
|
/* as published by the Free Software Foundation; either version 2 */
|
|
/* of the License, or (at your option) any later version. */
|
|
/* */
|
|
/* This program is distributed in the hope that it will be useful, */
|
|
/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
|
|
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
|
|
/* GNU Library General Public License for more details. */
|
|
|
|
#if defined(TEST_FOR_COMPARE_AND_SWAP)
|
|
|
|
extern int __pthread_has_cas;
|
|
extern int __pthread_compare_and_swap(long * ptr, long oldval, long newval,
|
|
int * spinlock);
|
|
|
|
static inline int compare_and_swap(long * ptr, long oldval, long newval,
|
|
int * spinlock)
|
|
{
|
|
if (__builtin_expect (__pthread_has_cas, 1))
|
|
return __compare_and_swap(ptr, oldval, newval);
|
|
else
|
|
return __pthread_compare_and_swap(ptr, oldval, newval, spinlock);
|
|
}
|
|
|
|
#elif defined(HAS_COMPARE_AND_SWAP)
|
|
|
|
static inline int compare_and_swap(long * ptr, long oldval, long newval,
|
|
int * spinlock)
|
|
{
|
|
return __compare_and_swap(ptr, oldval, newval);
|
|
}
|
|
|
|
#else
|
|
|
|
extern int __pthread_compare_and_swap(long * ptr, long oldval, long newval,
|
|
int * spinlock);
|
|
|
|
static inline int compare_and_swap(long * ptr, long oldval, long newval,
|
|
int * spinlock)
|
|
{
|
|
return __pthread_compare_and_swap(ptr, oldval, newval, spinlock);
|
|
}
|
|
|
|
#endif
|
|
|
|
/* Internal locks */
|
|
|
|
extern void internal_function __pthread_lock(struct _pthread_fastlock * lock,
|
|
pthread_descr self);
|
|
extern void internal_function __pthread_unlock(struct _pthread_fastlock *lock);
|
|
|
|
static inline void __pthread_init_lock(struct _pthread_fastlock * lock)
|
|
{
|
|
lock->__status = 0;
|
|
lock->__spinlock = 0;
|
|
}
|
|
|
|
static inline int __pthread_trylock (struct _pthread_fastlock * lock)
|
|
{
|
|
long oldstatus;
|
|
|
|
do {
|
|
oldstatus = lock->__status;
|
|
if (oldstatus != 0) return EBUSY;
|
|
} while(! compare_and_swap(&lock->__status, 0, 1, &lock->__spinlock));
|
|
return 0;
|
|
}
|
|
|
|
#define LOCK_INITIALIZER {0, 0}
|
|
|
|
/* Operations on pthread_atomic, which is defined in internals.h */
|
|
|
|
static inline long atomic_increment(struct pthread_atomic *pa)
|
|
{
|
|
long oldval;
|
|
|
|
do {
|
|
oldval = pa->p_count;
|
|
} while (!compare_and_swap(&pa->p_count, oldval, oldval + 1, &pa->p_spinlock));
|
|
|
|
return oldval;
|
|
}
|
|
|
|
|
|
static inline long atomic_decrement(struct pthread_atomic *pa)
|
|
{
|
|
long oldval;
|
|
|
|
do {
|
|
oldval = pa->p_count;
|
|
} while (!compare_and_swap(&pa->p_count, oldval, oldval - 1, &pa->p_spinlock));
|
|
|
|
return oldval;
|
|
}
|
|
|
|
#define ATOMIC_INITIALIZER { 0, 0 }
|
|
|