On 07/10/2019 14:50, Steven Price wrote: > 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, along > with a commented out call to panfrost_core_dump() which has never > existed in mainline. > > Signed-off-by: Steven Price <steven.pr...@arm.com> > --- > This is a tidied up version of the patch orginally posted here: > http://lkml.kernel.org/r/26ae2a4d-8df1-e8db-3060-41638ed63e2a%40arm.com > > drivers/gpu/drm/panfrost/panfrost_job.c | 17 +++++++++++------ > 1 file changed, 11 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c > b/drivers/gpu/drm/panfrost/panfrost_job.c > index a58551668d9a..dcc9a7603685 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++) { > @@ -398,7 +404,6 @@ static void panfrost_job_timedout(struct drm_sched_job > *sched_job) > } > spin_unlock_irqrestore(&pfdev->js->job_lock, flags); > > - /* panfrost_core_dump(pfdev); */ > > panfrost_devfreq_record_transition(pfdev, js); > panfrost_device_reset(pfdev); >
It ran successfully 10 dEQP tests without crashing the Amlogic S912 with Mali T820: Tested-by: Neil Armstrong <narmstr...@baylibre.com>
