diff options
Diffstat (limited to 'lib/libpthread/thread/thr_cancel.c')
| -rw-r--r-- | lib/libpthread/thread/thr_cancel.c | 271 |
1 files changed, 271 insertions, 0 deletions
diff --git a/lib/libpthread/thread/thr_cancel.c b/lib/libpthread/thread/thr_cancel.c new file mode 100644 index 0000000..23e0dfa --- /dev/null +++ b/lib/libpthread/thread/thr_cancel.c @@ -0,0 +1,271 @@ +/* + * David Leonard <d@openbsd.org>, 1999. Public domain. + * $FreeBSD$ + */ +#include <sys/errno.h> +#include <pthread.h> +#include "thr_private.h" + +__weak_reference(_pthread_cancel, pthread_cancel); +__weak_reference(_pthread_setcancelstate, pthread_setcancelstate); +__weak_reference(_pthread_setcanceltype, pthread_setcanceltype); +__weak_reference(_pthread_testcancel, pthread_testcancel); + +static int checkcancel(struct pthread *curthread); +static void testcancel(struct pthread *curthread); +static void finish_cancellation(void *arg); + +int +_pthread_cancel(pthread_t pthread) +{ + struct pthread *curthread = _get_curthread(); + int ret; + + if ((ret = _thr_ref_add(curthread, pthread, /*include dead*/0)) == 0) { + /* + * Take the scheduling lock while we change the cancel flags. + */ + THR_SCHED_LOCK(curthread, pthread); + + if (((pthread->cancelflags & PTHREAD_CANCEL_DISABLE) != 0) || + (((pthread->cancelflags & THR_AT_CANCEL_POINT) == 0) && + ((pthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) == 0))) + /* Just mark it for cancellation: */ + pthread->cancelflags |= THR_CANCELLING; + else { + /* + * Check if we need to kick it back into the + * run queue: + */ + switch (pthread->state) { + case PS_RUNNING: + /* No need to resume: */ + pthread->cancelflags |= THR_CANCELLING; + break; + + case PS_LOCKWAIT: + /* + * These can't be removed from the queue. + * Just mark it as cancelling and tell it + * to yield once it leaves the critical + * region. + */ + pthread->cancelflags |= THR_CANCELLING; + pthread->critical_yield = 1; + break; + + case PS_SLEEP_WAIT: + case PS_SIGSUSPEND: + case PS_SIGWAIT: + /* Interrupt and resume: */ + pthread->interrupted = 1; + pthread->cancelflags |= THR_CANCELLING; + _thr_setrunnable_unlocked(pthread); + break; + + case PS_JOIN: + /* + * Disconnect the thread from the joinee: + */ + if (pthread->join_status.thread != NULL) { + pthread->join_status.thread->joiner + = NULL; + pthread->join_status.thread = NULL; + } + pthread->cancelflags |= THR_CANCELLING; + _thr_setrunnable_unlocked(pthread); + break; + + case PS_SUSPENDED: + case PS_MUTEX_WAIT: + case PS_COND_WAIT: + /* + * Threads in these states may be in queues. + * In order to preserve queue integrity, the + * cancelled thread must remove itself from the + * queue. Mark the thread as interrupted and + * needing cancellation, and set the state to + * running. When the thread resumes, it will + * remove itself from the queue and call the + * cancellation completion routine. + */ + pthread->interrupted = 1; + pthread->cancelflags |= THR_CANCEL_NEEDED; + _thr_setrunnable_unlocked(pthread); + pthread->continuation = finish_cancellation; + break; + + case PS_DEAD: + case PS_DEADLOCK: + case PS_STATE_MAX: + /* Ignore - only here to silence -Wall: */ + break; + } + if ((pthread->blocked != 0) && + ((pthread->cancelflags & THR_AT_CANCEL_POINT) != 0)) + kse_thr_interrupt(&pthread->tmbx); + } + + /* + * Release the thread's scheduling lock and remove the + * reference: + */ + THR_SCHED_UNLOCK(curthread, pthread); + _thr_ref_delete(curthread, pthread); + } + return (ret); +} + +int +_pthread_setcancelstate(int state, int *oldstate) +{ + struct pthread *curthread = _get_curthread(); + int ostate; + int ret; + int need_exit = 0; + + /* Take the scheduling lock while fiddling with the thread's state: */ + THR_SCHED_LOCK(curthread, curthread); + + ostate = curthread->cancelflags & PTHREAD_CANCEL_DISABLE; + + switch (state) { + case PTHREAD_CANCEL_ENABLE: + if (oldstate != NULL) + *oldstate = ostate; + curthread->cancelflags &= ~PTHREAD_CANCEL_DISABLE; + if ((curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) != 0) + need_exit = checkcancel(curthread); + ret = 0; + break; + case PTHREAD_CANCEL_DISABLE: + if (oldstate != NULL) + *oldstate = ostate; + curthread->cancelflags |= PTHREAD_CANCEL_DISABLE; + ret = 0; + break; + default: + ret = EINVAL; + } + + THR_SCHED_UNLOCK(curthread, curthread); + if (need_exit != 0) { + _thr_exit_cleanup(); + pthread_exit(PTHREAD_CANCELED); + PANIC("cancel"); + } + return (ret); +} + +int +_pthread_setcanceltype(int type, int *oldtype) +{ + struct pthread *curthread = _get_curthread(); + int otype; + int ret; + int need_exit = 0; + + /* Take the scheduling lock while fiddling with the state: */ + THR_SCHED_LOCK(curthread, curthread); + + otype = curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS; + switch (type) { + case PTHREAD_CANCEL_ASYNCHRONOUS: + if (oldtype != NULL) + *oldtype = otype; + curthread->cancelflags |= PTHREAD_CANCEL_ASYNCHRONOUS; + need_exit = checkcancel(curthread); + ret = 0; + break; + case PTHREAD_CANCEL_DEFERRED: + if (oldtype != NULL) + *oldtype = otype; + curthread->cancelflags &= ~PTHREAD_CANCEL_ASYNCHRONOUS; + ret = 0; + break; + default: + ret = EINVAL; + } + + THR_SCHED_UNLOCK(curthread, curthread); + if (need_exit != 0) { + _thr_exit_cleanup(); + pthread_exit(PTHREAD_CANCELED); + PANIC("cancel"); + } + return (ret); +} + +static int +checkcancel(struct pthread *curthread) +{ + if (((curthread->cancelflags & PTHREAD_CANCEL_DISABLE) == 0) && + ((curthread->cancelflags & THR_CANCELLING) != 0)) { + /* + * It is possible for this thread to be swapped out + * while performing cancellation; do not allow it + * to be cancelled again. + */ + curthread->cancelflags &= ~THR_CANCELLING; + return (1); + } + else + return (0); +} + +static void +testcancel(struct pthread *curthread) +{ + /* Take the scheduling lock while fiddling with the state: */ + THR_SCHED_LOCK(curthread, curthread); + + if (checkcancel(curthread) != 0) { + /* Unlock before exiting: */ + THR_SCHED_UNLOCK(curthread, curthread); + + _thr_exit_cleanup(); + pthread_exit(PTHREAD_CANCELED); + PANIC("cancel"); + } + + THR_SCHED_UNLOCK(curthread, curthread); +} + +void +_pthread_testcancel(void) +{ + struct pthread *curthread = _get_curthread(); + + testcancel(curthread); +} + +void +_thr_enter_cancellation_point(struct pthread *thread) +{ + /* Look for a cancellation before we block: */ + testcancel(thread); + thread->cancelflags |= THR_AT_CANCEL_POINT; +} + +void +_thr_leave_cancellation_point(struct pthread *thread) +{ + thread->cancelflags &= ~THR_AT_CANCEL_POINT; + /* Look for a cancellation after we unblock: */ + testcancel(thread); +} + +static void +finish_cancellation(void *arg) +{ + struct pthread *curthread = _get_curthread(); + + curthread->continuation = NULL; + curthread->interrupted = 0; + + if ((curthread->cancelflags & THR_CANCEL_NEEDED) != 0) { + curthread->cancelflags &= ~THR_CANCEL_NEEDED; + _thr_exit_cleanup(); + pthread_exit(PTHREAD_CANCELED); + } +} |
