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re PR libgomp/51376 (libgomp taskwait failure)

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PR libgomp/51376
	PR libgomp/56073
	* task.c (GOMP_task): Revert 2011-12-09 change.
	(GOMP_taskwait): Likewise.  Instead use atomic load with acquire
	barrier to read task->children..
	(gomp_barrier_handle_tasks): ..and matching atomic store with
	release barrier here when setting parent->children to NULL.

From-SVN: r195370
This commit is contained in:
Alan Modra 2013-01-22 22:11:53 +10:30 • committed by Alan Modra
parent e18600419e
commit 9a64728823
2 changed files with 21 additions and 5 deletions
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10
libgomp/ChangeLog
View file

@ -1,3 +1,13 @@
2013-01-22 Alan Modra <amodra@gmail.com>
PR libgomp/51376
PR libgomp/56073
* task.c (GOMP_task): Revert 2011-12-09 change.
(GOMP_taskwait): Likewise. Instead use atomic load with acquire
barrier to read task->children..
(gomp_barrier_handle_tasks): ..and matching atomic store with
release barrier here when setting parent->children to NULL.
2013-01-16 Jakub Jelinek <jakub@redhat.com>
Tobias Burnus <burnus@net-b.de>

16
libgomp/task.c
View file

@ -116,11 +116,10 @@ GOMP_task (void (*fn) (void *), void *data, void (*cpyfn) (void *, void *),
}
else
fn (data);
if (team != NULL)
if (task.children != NULL)
{
gomp_mutex_lock (&team->task_lock);
if (task.children != NULL)
gomp_clear_parent (task.children);
gomp_clear_parent (task.children);
gomp_mutex_unlock (&team->task_lock);
}
gomp_end_task ();
@ -258,7 +257,13 @@ gomp_barrier_handle_tasks (gomp_barrier_state_t state)
parent->children = child_task->next_child;
else
{
parent->children = NULL;
/* We access task->children in GOMP_taskwait
outside of the task lock mutex region, so
need a release barrier here to ensure memory
written by child_task->fn above is flushed
before the NULL is written. */
__atomic_store_n (&parent->children, NULL,
MEMMODEL_RELEASE);
if (parent->in_taskwait)
gomp_sem_post (&parent->taskwait_sem);
}
@ -291,7 +296,8 @@ GOMP_taskwait (void)
struct gomp_task *child_task = NULL;
struct gomp_task *to_free = NULL;
if (task == NULL || team == NULL)
if (task == NULL
|| __atomic_load_n (&task->children, MEMMODEL_ACQUIRE) == NULL)
return;
gomp_mutex_lock (&team->task_lock);