Hi Lucas,
thanks a lot for taking care of that, but there is one thing you have missed:
It is perfectly possible that the job is the last one on the list and list_next_entry() doesn't test for that, e.g. it never return NULL.
BTW: There are also quite a lot of other things we could optimize here. So if you need something todo, just ping me :)
Cheers, Christian.
Am 03.08.2018 um 15:18 schrieb Lucas Stach:
drm_sched_job_finish() is a work item scheduled for each finished job on a unbound system workqueue. This means the workers can execute out of order with regard to the real hardware job completions.
If this happens queueing a timeout worker for the first job on the ring mirror list is wrong, as this may be a job which has already finished executing. Fix this by reorganizing the code to always queue the worker for the next job on the list, if this job hasn't finished yet. This is robust against a potential reordering of the finish workers.
Also move out the timeout worker cancelling, so that we don't need to take the job list lock twice. As a small optimization list_del is used to remove the job from the ring mirror list, as there is no need to reinit the list head in the job we are about to free.
Signed-off-by: Lucas Stach l.stach@pengutronix.de
drivers/gpu/drm/scheduler/gpu_scheduler.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c index 44d480768dfe..0be2859d7b80 100644 --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c @@ -452,24 +452,22 @@ static void drm_sched_job_finish(struct work_struct *work) finish_work); struct drm_gpu_scheduler *sched = s_job->sched;
- /* remove job from ring_mirror_list */
- if (sched->timeout != MAX_SCHEDULE_TIMEOUT)
cancel_delayed_work_sync(&s_job->work_tdr);- spin_lock(&sched->job_list_lock);
- list_del_init(&s_job->node); if (sched->timeout != MAX_SCHEDULE_TIMEOUT) {
struct drm_sched_job *next;spin_unlock(&sched->job_list_lock);cancel_delayed_work_sync(&s_job->work_tdr);spin_lock(&sched->job_list_lock);
struct drm_sched_job *next = list_next_entry(s_job, node);/* queue TDR for next job */
next = list_first_entry_or_null(&sched->ring_mirror_list,struct drm_sched_job, node);if (next)
if (next != s_job &&!dma_fence_is_signaled(&s_job->s_fence->finished)) schedule_delayed_work(&next->work_tdr, sched->timeout);- /* remove job from ring_mirror_list */
- list_del(&s_job->node); spin_unlock(&sched->job_list_lock);
- dma_fence_put(&s_job->s_fence->finished); sched->ops->free_job(s_job); }