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authorSteven Price <steven.price@arm.com>2019-10-09 10:44:55 +0100
committerRob Herring <robh@kernel.org>2019-10-15 11:38:22 -0500
commit5b3ec8134f5f9fa1ed0a538441a495521078bbee (patch)
treef6ef968ec57b77e4c8f44d388b4cc427a1ae347b
parenteda6d764ac33d9ce8d656fa381f05b3feae09085 (diff)
drm/panfrost: Handle resetting on timeout better
Panfrost uses multiple schedulers (one for each slot, so 2 in reality), and on a timeout has to stop all the schedulers to safely perform a reset. However more than one scheduler can trigger a timeout at the same time. This race condition results in jobs being freed while they are still in use. When stopping other slots use cancel_delayed_work_sync() to ensure that any timeout started for that slot has completed. Also use mutex_trylock() to obtain reset_lock. This means that only one thread attempts the reset, the other threads will simply complete without doing anything (the first thread will wait for this in the call to cancel_delayed_work_sync()). While we're here and since the function is already dependent on sched_job not being NULL, let's remove the unnecessary checks. Fixes: aa20236784ab ("drm/panfrost: Prevent concurrent resets") Tested-by: Neil Armstrong <narmstrong@baylibre.com> Signed-off-by: Steven Price <steven.price@arm.com> Cc: stable@vger.kernel.org Signed-off-by: Rob Herring <robh@kernel.org> Link: https://patchwork.freedesktop.org/patch/msgid/20191009094456.9704-1-steven.price@arm.com
-rw-r--r--drivers/gpu/drm/panfrost/panfrost_job.c16
1 files changed, 11 insertions, 5 deletions
diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index a58551668d9a..21f34d44aac2 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -381,13 +381,19 @@ static void panfrost_job_timedout(struct drm_sched_job *sched_job)
job_read(pfdev, JS_TAIL_LO(js)),
sched_job);
- mutex_lock(&pfdev->reset_lock);
+ if (!mutex_trylock(&pfdev->reset_lock))
+ return;
- for (i = 0; i < NUM_JOB_SLOTS; i++)
- drm_sched_stop(&pfdev->js->queue[i].sched, sched_job);
+ for (i = 0; i < NUM_JOB_SLOTS; i++) {
+ struct drm_gpu_scheduler *sched = &pfdev->js->queue[i].sched;
+
+ drm_sched_stop(sched, sched_job);
+ if (js != i)
+ /* Ensure any timeouts on other slots have finished */
+ cancel_delayed_work_sync(&sched->work_tdr);
+ }
- if (sched_job)
- drm_sched_increase_karma(sched_job);
+ drm_sched_increase_karma(sched_job);
spin_lock_irqsave(&pfdev->js->job_lock, flags);
for (i = 0; i < NUM_JOB_SLOTS; i++) {