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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!).

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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.
This commit is contained in:
Ulrich Drepper
2000-01-05 02:09:12 +00:00
parent f19f2b3443
commit 1d2fc9b3c5
14 changed files with 719 additions and 107 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
linuxthreads/join.c
View File

@@ -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);