Messages in this thread | | | Subject | Re: [PATCH] drm/panfrost: Handle resetting on timeout better | From | Tomeu Vizoso <> | Date | Mon, 7 Oct 2019 09:14:04 -0700 |
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On 10/7/19 6:09 AM, Neil Armstrong wrote: > Hi Steven, > > 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. >> > > A Fixes: tags would be welcome here so it would be backported to v5.3 > >> Signed-off-by: Steven Price <steven.price@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); > > Indeed looks cleaner. > >> >> 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); */ > > This should be cleaned in another patch !
Seems to me that this should be some kind of TODO, see etnaviv_core_dump() for the kind of things we could be doing.
Maybe we can delete this line and mention this in the TODO file?
Cheers,
Tomeu
>> >> panfrost_devfreq_record_transition(pfdev, js); >> panfrost_device_reset(pfdev); >> > > Thanks, > Testing it right now with the last change removed (doesn't apply on v5.3 with it), > results in a few hours... or minutes ! > > > Neil >
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