291 lines
7.2 KiB
C
291 lines
7.2 KiB
C
/*
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* David Leonard <d@openbsd.org>, 1999. Public domain.
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* $FreeBSD$
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*/
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#include <sys/errno.h>
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#include <pthread.h>
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#include "thr_private.h"
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__weak_reference(_pthread_cancel, pthread_cancel);
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__weak_reference(_pthread_setcancelstate, pthread_setcancelstate);
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__weak_reference(_pthread_setcanceltype, pthread_setcanceltype);
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__weak_reference(_pthread_testcancel, pthread_testcancel);
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static int checkcancel(struct pthread *curthread);
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static void testcancel(struct pthread *curthread);
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static void finish_cancellation(void *arg);
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int
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_pthread_cancel(pthread_t pthread)
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{
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struct pthread *curthread = _get_curthread();
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struct pthread *joinee = NULL;
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int ret;
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if ((ret = _thr_ref_add(curthread, pthread, /*include dead*/0)) == 0) {
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/*
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* Take the scheduling lock while we change the cancel flags.
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*/
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THR_SCHED_LOCK(curthread, pthread);
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if (pthread->flags & THR_FLAGS_EXITING) {
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THR_SCHED_UNLOCK(curthread, pthread);
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_thr_ref_delete(curthread, pthread);
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return (ESRCH);
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}
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if (((pthread->cancelflags & PTHREAD_CANCEL_DISABLE) != 0) ||
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(((pthread->cancelflags & THR_AT_CANCEL_POINT) == 0) &&
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((pthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) == 0)))
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/* Just mark it for cancellation: */
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pthread->cancelflags |= THR_CANCELLING;
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else {
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/*
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* Check if we need to kick it back into the
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* run queue:
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*/
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switch (pthread->state) {
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case PS_RUNNING:
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/* No need to resume: */
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pthread->cancelflags |= THR_CANCELLING;
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break;
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case PS_LOCKWAIT:
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/*
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* These can't be removed from the queue.
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* Just mark it as cancelling and tell it
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* to yield once it leaves the critical
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* region.
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*/
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pthread->cancelflags |= THR_CANCELLING;
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pthread->critical_yield = 1;
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break;
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case PS_SLEEP_WAIT:
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case PS_SIGSUSPEND:
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case PS_SIGWAIT:
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/* Interrupt and resume: */
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pthread->interrupted = 1;
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pthread->cancelflags |= THR_CANCELLING;
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_thr_setrunnable_unlocked(pthread);
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break;
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case PS_JOIN:
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/* Disconnect the thread from the joinee: */
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joinee = pthread->join_status.thread;
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pthread->join_status.thread = NULL;
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pthread->cancelflags |= THR_CANCELLING;
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_thr_setrunnable_unlocked(pthread);
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if ((joinee != NULL) &&
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(pthread->kseg == joinee->kseg)) {
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/* Remove the joiner from the joinee. */
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joinee->joiner = NULL;
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joinee = NULL;
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}
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break;
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case PS_SUSPENDED:
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case PS_MUTEX_WAIT:
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case PS_COND_WAIT:
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/*
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* Threads in these states may be in queues.
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* In order to preserve queue integrity, the
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* cancelled thread must remove itself from the
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* queue. Mark the thread as interrupted and
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* needing cancellation, and set the state to
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* running. When the thread resumes, it will
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* remove itself from the queue and call the
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* cancellation completion routine.
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*/
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pthread->interrupted = 1;
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pthread->cancelflags |= THR_CANCEL_NEEDED;
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_thr_setrunnable_unlocked(pthread);
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pthread->continuation = finish_cancellation;
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break;
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case PS_DEAD:
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case PS_DEADLOCK:
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case PS_STATE_MAX:
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/* Ignore - only here to silence -Wall: */
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break;
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}
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if ((pthread->blocked != 0) &&
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((pthread->cancelflags & THR_AT_CANCEL_POINT) != 0))
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kse_thr_interrupt(&pthread->tmbx, -1);
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}
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/*
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* Release the thread's scheduling lock and remove the
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* reference:
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*/
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THR_SCHED_UNLOCK(curthread, pthread);
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_thr_ref_delete(curthread, pthread);
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if ((joinee != NULL) &&
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(_thr_ref_add(curthread, joinee, /* include dead */1) == 0)) {
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/* Remove the joiner from the joinee. */
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THR_SCHED_LOCK(curthread, joinee);
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joinee->joiner = NULL;
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THR_SCHED_UNLOCK(curthread, joinee);
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_thr_ref_delete(curthread, joinee);
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}
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}
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return (ret);
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}
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int
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_pthread_setcancelstate(int state, int *oldstate)
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{
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struct pthread *curthread = _get_curthread();
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int ostate;
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int ret;
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int need_exit = 0;
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/* Take the scheduling lock while fiddling with the thread's state: */
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THR_SCHED_LOCK(curthread, curthread);
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ostate = curthread->cancelflags & PTHREAD_CANCEL_DISABLE;
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switch (state) {
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case PTHREAD_CANCEL_ENABLE:
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curthread->cancelflags &= ~PTHREAD_CANCEL_DISABLE;
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if ((curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) != 0)
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need_exit = checkcancel(curthread);
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ret = 0;
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break;
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case PTHREAD_CANCEL_DISABLE:
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curthread->cancelflags |= PTHREAD_CANCEL_DISABLE;
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ret = 0;
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break;
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default:
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ret = EINVAL;
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}
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THR_SCHED_UNLOCK(curthread, curthread);
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if (need_exit != 0) {
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_thr_exit_cleanup();
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pthread_exit(PTHREAD_CANCELED);
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PANIC("cancel");
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}
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if (ret == 0 && oldstate != NULL)
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*oldstate = ostate;
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return (ret);
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}
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int
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_pthread_setcanceltype(int type, int *oldtype)
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{
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struct pthread *curthread = _get_curthread();
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int otype;
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int ret;
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int need_exit = 0;
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/* Take the scheduling lock while fiddling with the state: */
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THR_SCHED_LOCK(curthread, curthread);
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otype = curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS;
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switch (type) {
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case PTHREAD_CANCEL_ASYNCHRONOUS:
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curthread->cancelflags |= PTHREAD_CANCEL_ASYNCHRONOUS;
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need_exit = checkcancel(curthread);
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ret = 0;
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break;
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case PTHREAD_CANCEL_DEFERRED:
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curthread->cancelflags &= ~PTHREAD_CANCEL_ASYNCHRONOUS;
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ret = 0;
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break;
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default:
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ret = EINVAL;
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}
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THR_SCHED_UNLOCK(curthread, curthread);
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if (need_exit != 0) {
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_thr_exit_cleanup();
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pthread_exit(PTHREAD_CANCELED);
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PANIC("cancel");
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}
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if (ret == 0 && oldtype != NULL)
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*oldtype = otype;
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return (ret);
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}
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static int
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checkcancel(struct pthread *curthread)
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{
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if (((curthread->cancelflags & PTHREAD_CANCEL_DISABLE) == 0) &&
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((curthread->cancelflags & THR_CANCELLING) != 0)) {
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/*
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* It is possible for this thread to be swapped out
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* while performing cancellation; do not allow it
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* to be cancelled again.
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*/
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curthread->cancelflags &= ~THR_CANCELLING;
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return (1);
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}
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else
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return (0);
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}
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static void
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testcancel(struct pthread *curthread)
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{
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/* Take the scheduling lock while fiddling with the state: */
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if (checkcancel(curthread) != 0) {
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/* Unlock before exiting: */
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THR_SCHED_UNLOCK(curthread, curthread);
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_thr_exit_cleanup();
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pthread_exit(PTHREAD_CANCELED);
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PANIC("cancel");
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}
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}
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void
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_pthread_testcancel(void)
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{
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struct pthread *curthread = _get_curthread();
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THR_SCHED_LOCK(curthread, curthread);
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testcancel(curthread);
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THR_SCHED_UNLOCK(curthread, curthread);
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}
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void
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_thr_enter_cancellation_point(struct pthread *thread)
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{
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/* Look for a cancellation before we block: */
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THR_SCHED_LOCK(thread, thread);
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testcancel(thread);
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thread->cancelflags |= THR_AT_CANCEL_POINT;
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THR_SCHED_UNLOCK(thread, thread);
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}
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void
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_thr_leave_cancellation_point(struct pthread *thread)
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{
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THR_SCHED_LOCK(thread, thread);
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thread->cancelflags &= ~THR_AT_CANCEL_POINT;
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/* Look for a cancellation after we unblock: */
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testcancel(thread);
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THR_SCHED_UNLOCK(thread, thread);
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}
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static void
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finish_cancellation(void *arg)
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{
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struct pthread *curthread = _get_curthread();
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curthread->continuation = NULL;
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curthread->interrupted = 0;
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THR_SCHED_LOCK(curthread, curthread);
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if ((curthread->cancelflags & THR_CANCEL_NEEDED) != 0) {
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curthread->cancelflags &= ~THR_CANCEL_NEEDED;
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THR_SCHED_UNLOCK(curthread, curthread);
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_thr_exit_cleanup();
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pthread_exit(PTHREAD_CANCELED);
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}
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THR_SCHED_UNLOCK(curthread, curthread);
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}
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