blob: c9f0c24582ad0c2a92fa18288143fd1c1a4d0a80 [file] [log] [blame]
From 01bcd855bee58243a1720b6a1af7140ad7b4b4cd Mon Sep 17 00:00:00 2001
From: Steven Price <>
Date: Wed, 9 Oct 2019 10:44:55 +0100
Subject: [PATCH] drm/panfrost: Handle resetting on timeout better
commit 5b3ec8134f5f9fa1ed0a538441a495521078bbee upstream.
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
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 <>
Signed-off-by: Steven Price <>
Signed-off-by: Rob Herring <>
Signed-off-by: Paul Gortmaker <>
diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index a5716c8fe8b3..390b0c045206 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -384,13 +384,19 @@ static void panfrost_job_timedout(struct drm_sched_job *sched_job)
job_read(pfdev, JS_TAIL_LO(js)),
- 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);
+ for (i = 0; i < NUM_JOB_SLOTS; i++) {
+ struct drm_gpu_scheduler *sched = &pfdev->js->queue[i].sched;
+ drm_sched_stop(sched);
+ 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);
/* panfrost_core_dump(pfdev); */