Hi!
As can be seen on the depend-8.c testcase, only trying to schedule
taskgroup->children in GOMP_taskgroup_end can lead to deadlock
if depend clauses are involved - some task in the current taskgroup
can depend on a task with the same parent, but from another taskgroup
(one of the parent taskgroups).
This patch will schedule taskgroup->children if available, but if
there are none and taskgroup->num_children is still non-zero, attempts
to schedule parent->children. num_children is increased on deferred
task creation, so it includes tasks in the taskgroup waiting on
dependencies, while children linked list includes only tasks ready to
be scheduled.
Bootstrapped/regtested on x86_64-linux and i686-linux, committed to trunk
and 4.9 branch.
2014-08-04 Jakub Jelinek <ja...@redhat.com>
* task.c (GOMP_taskgroup_end): If taskgroup->num_children
is not zero, but taskgroup->children is NULL and there are
any task->children, schedule those instead of waiting.
* testsuite/libgomp.c/depend-6.c: New test.
* testsuite/libgomp.c/depend-7.c: New test.
* testsuite/libgomp.c/depend-8.c: New test.
* testsuite/libgomp.c/depend-9.c: New test.
* testsuite/libgomp.c/depend-10.c: New test.
--- libgomp/task.c.jj 2014-08-01 10:04:11.000000000 +0200
+++ libgomp/task.c 2014-08-04 10:02:10.931449395 +0200
@@ -1115,18 +1115,26 @@ GOMP_taskgroup_end (void)
if (taskgroup->children == NULL)
{
if (taskgroup->num_children)
- goto do_wait;
- gomp_mutex_unlock (&team->task_lock);
- if (to_free)
{
- gomp_finish_task (to_free);
- free (to_free);
+ if (task->children == NULL)
+ goto do_wait;
+ child_task = task->children;
+ }
+ else
+ {
+ gomp_mutex_unlock (&team->task_lock);
+ if (to_free)
+ {
+ gomp_finish_task (to_free);
+ free (to_free);
+ }
+ goto finish;
}
- goto finish;
}
- if (taskgroup->children->kind == GOMP_TASK_WAITING)
+ else
+ child_task = taskgroup->children;
+ if (child_task->kind == GOMP_TASK_WAITING)
{
- child_task = taskgroup->children;
cancelled
= gomp_task_run_pre (child_task, child_task->parent, taskgroup,
team);
@@ -1143,6 +1151,7 @@ GOMP_taskgroup_end (void)
}
else
{
+ child_task = NULL;
do_wait:
/* All tasks we are waiting for are already running
in other threads. Wait for them. */
@@ -1174,20 +1183,9 @@ GOMP_taskgroup_end (void)
finish_cancelled:;
size_t new_tasks
= gomp_task_run_post_handle_depend (child_task, team);
- child_task->prev_taskgroup->next_taskgroup
- = child_task->next_taskgroup;
- child_task->next_taskgroup->prev_taskgroup
- = child_task->prev_taskgroup;
- --taskgroup->num_children;
- if (taskgroup->children == child_task)
- {
- if (child_task->next_taskgroup != child_task)
- taskgroup->children = child_task->next_taskgroup;
- else
- taskgroup->children = NULL;
- }
gomp_task_run_post_remove_parent (child_task);
gomp_clear_parent (child_task->children);
+ gomp_task_run_post_remove_taskgroup (child_task);
to_free = child_task;
child_task = NULL;
team->task_count--;
--- libgomp/testsuite/libgomp.c/depend-6.c.jj 2014-08-04 10:31:59.877674051
+0200
+++ libgomp/testsuite/libgomp.c/depend-6.c 2014-08-04 10:31:28.531825917
+0200
@@ -0,0 +1,3 @@
+/* { dg-set-target-env-var OMP_NUM_THREADS "1" } */
+
+#include "depend-1.c"
--- libgomp/testsuite/libgomp.c/depend-7.c.jj 2014-08-04 10:31:59.877674051
+0200
+++ libgomp/testsuite/libgomp.c/depend-7.c 2014-08-04 10:32:06.328641868
+0200
@@ -0,0 +1,3 @@
+/* { dg-set-target-env-var OMP_NUM_THREADS "1" } */
+
+#include "depend-2.c"
--- libgomp/testsuite/libgomp.c/depend-8.c.jj 2014-08-04 10:31:59.877674051
+0200
+++ libgomp/testsuite/libgomp.c/depend-8.c 2014-08-04 10:32:12.556611152
+0200
@@ -0,0 +1,3 @@
+/* { dg-set-target-env-var OMP_NUM_THREADS "1" } */
+
+#include "depend-3.c"
--- libgomp/testsuite/libgomp.c/depend-9.c.jj 2014-08-04 10:31:59.877674051
+0200
+++ libgomp/testsuite/libgomp.c/depend-9.c 2014-08-04 10:32:18.501579242
+0200
@@ -0,0 +1,3 @@
+/* { dg-set-target-env-var OMP_NUM_THREADS "1" } */
+
+#include "depend-4.c"
--- libgomp/testsuite/libgomp.c/depend-10.c.jj 2014-08-04 10:31:59.877674051
+0200
+++ libgomp/testsuite/libgomp.c/depend-10.c 2014-08-04 10:32:25.070548201
+0200
@@ -0,0 +1,3 @@
+/* { dg-set-target-env-var OMP_NUM_THREADS "1" } */
+
+#include "depend-5.c"
Jakub
