From 1d2fc9b3c59d0e83e04139ddf633731264b76ea2 Mon Sep 17 00:00:00 2001 From: Ulrich Drepper Date: Wed, 5 Jan 2000 02:09:12 +0000 Subject: 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!). 2000-01-03 Kaz Kylheku 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. --- linuxthreads/join.c | 48 ++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 44 insertions(+), 4 deletions(-) (limited to 'linuxthreads/join.c') diff --git a/linuxthreads/join.c b/linuxthreads/join.c index 71db541391..5e6b78ab3b 100644 --- a/linuxthreads/join.c +++ b/linuxthreads/join.c @@ -79,12 +79,37 @@ void pthread_exit(void * retval) _exit(0); } +/* Function called by pthread_cancel to remove the thread from + waiting on a condition variable queue. */ + +static int join_extricate_func(void *obj, pthread_descr th) +{ + volatile pthread_descr self = thread_self(); + pthread_handle handle = obj; + pthread_descr jo; + int did_remove = 0; + + __pthread_lock(&handle->h_lock, self); + jo = handle->h_descr; + did_remove = jo->p_joining != NULL; + jo->p_joining = NULL; + __pthread_unlock(&handle->h_lock); + + return did_remove; +} + int pthread_join(pthread_t thread_id, void ** thread_return) { volatile pthread_descr self = thread_self(); struct pthread_request request; pthread_handle handle = thread_handle(thread_id); pthread_descr th; + pthread_extricate_if extr; + int already_canceled = 0; + + /* Set up extrication interface */ + extr.pu_object = handle; + extr.pu_extricate_func = join_extricate_func; __pthread_lock(&handle->h_lock, self); if (invalid_handle(handle, thread_id)) { @@ -103,13 +128,28 @@ int pthread_join(pthread_t thread_id, void ** thread_return) } /* If not terminated yet, suspend ourselves. */ if (! th->p_terminated) { - th->p_joining = self; + /* Register extrication interface */ + __pthread_set_own_extricate_if(self, &extr); + if (!(THREAD_GETMEM(self, p_canceled) + && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE)) + th->p_joining = self; + else + already_canceled = 1; __pthread_unlock(&handle->h_lock); - suspend_with_cancellation(self); + + if (already_canceled) { + __pthread_set_own_extricate_if(self, 0); + pthread_exit(PTHREAD_CANCELED); + } + + suspend(self); + /* Deregister extrication interface */ + __pthread_set_own_extricate_if(self, 0); + /* This is a cancellation point */ - if (THREAD_GETMEM(self, p_canceled) + if (THREAD_GETMEM(self, p_woken_by_cancel) && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) { - th->p_joining = NULL; + THREAD_SETMEM(self, p_woken_by_cancel, 0); pthread_exit(PTHREAD_CANCELED); } __pthread_lock(&handle->h_lock, self); -- cgit v1.2.3