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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.
57 lines
1.9 KiB
C
57 lines
1.9 KiB
C
/* Linuxthreads - a simple clone()-based implementation of Posix */
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/* threads for Linux. */
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/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */
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/* */
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/* This program is free software; you can redistribute it and/or */
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/* modify it under the terms of the GNU Library General Public License */
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/* as published by the Free Software Foundation; either version 2 */
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/* of the License, or (at your option) any later version. */
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/* */
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/* This program is distributed in the hope that it will be useful, */
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/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
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/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
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/* GNU Library General Public License for more details. */
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/* Waiting queues */
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/* Waiting queues are represented by lists of thread descriptors
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linked through their p_nextwaiting field. The lists are kept
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sorted by decreasing priority, and then decreasing waiting time. */
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static inline void enqueue(pthread_descr * q, pthread_descr th)
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{
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int prio = th->p_priority;
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ASSERT(th->p_nextwaiting == NULL);
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for (; *q != NULL; q = &((*q)->p_nextwaiting)) {
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if (prio > (*q)->p_priority) {
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th->p_nextwaiting = *q;
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*q = th;
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return;
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}
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}
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*q = th;
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}
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static inline pthread_descr dequeue(pthread_descr * q)
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{
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pthread_descr th;
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th = *q;
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if (th != NULL) {
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*q = th->p_nextwaiting;
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th->p_nextwaiting = NULL;
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}
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return th;
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}
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static inline int remove_from_queue(pthread_descr * q, pthread_descr th)
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{
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for (; *q != NULL; q = &((*q)->p_nextwaiting)) {
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if (*q == th) {
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*q = th->p_nextwaiting;
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th->p_nextwaiting = NULL;
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return 1;
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}
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}
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return 0;
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}
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