On 11/26/19 4:08 AM, Christian König wrote:
Am 25.11.19 um 17:51 schrieb Steven Price:
On 25/11/2019 14:10, Andrey Grodzovsky wrote:
When the sched thread is parked we assume ring_mirror_list is
not accessed from here.
FWIW I don't think this is necessary. kthread_park() will wait until the
thread is parked, at which point the thread is stuck in kthread_parkme()
until unparked.
So all this does is avoid waiting for any cleanup jobs before parking -
which might be a reasonable goal in itself, but if so lets at least
document that.
Now that you mention it that is indeed wrong.
I wouldn't s call it wrong but superfluous in current code as indeed
once the thread is parked there will be no subsequent calls to
drm_sched_get_cleanup_job until the thread is unpacked back, if for
example we decide to call drm_sched_get_cleanup_job from a work item
which keeps scheduled it would be needed.
The real problem is that in the main thread we mangled the call to
kthread_parkme() into drm_sched_blocked() which can be called in
atomic context.
Where is the atomic context in wait_event_interruptible ? I seem no to
see any.
Andrey
I suggest to rework this so that the kthread_should_park() and
kthread_should_stop() test in wait_event_interruptible() come first
and then call kthread_parkme() outside of the wait_event_interruptible().
Regards,
Christian.
Steve
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
Reviewed-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/gpu/drm/scheduler/sched_main.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/scheduler/sched_main.c
b/drivers/gpu/drm/scheduler/sched_main.c
index d4cc728..6774955 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -635,9 +635,13 @@ drm_sched_get_cleanup_job(struct
drm_gpu_scheduler *sched)
struct drm_sched_job *job;
unsigned long flags;
- /* Don't destroy jobs while the timeout worker is running */
- if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
- !cancel_delayed_work(&sched->work_tdr))
+ /*
+ * Don't destroy jobs while the timeout worker is running OR thread
+ * is being parked and hence assumed to not touch ring_mirror_list
+ */
+ if ((sched->timeout != MAX_SCHEDULE_TIMEOUT &&
+ !cancel_delayed_work(&sched->work_tdr)) ||
+ __kthread_should_park(sched->thread))
return NULL;
spin_lock_irqsave(&sched->job_list_lock, flags);
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