On 30/10/2020 10:53, Boris Brezillon wrote:
We've fixed many races in panfrost_job_timedout() but some remain. Instead of trying to fix it again, let's simplify the logic and move the reset bits to a separate work scheduled when one of the queue reports a timeout.
v2:
- Use atomic_cmpxchg() to conditionally schedule the reset work (Steven Privce)
Fixes: 1a11a88cfd9a ("drm/panfrost: Fix job timeout handling") Cc: stable@vger.kernel.org Signed-off-by: Boris Brezillon boris.brezillon@collabora.com
LGTM!
Reviewed-by: Steven Price steven.price@arm.com
drivers/gpu/drm/panfrost/panfrost_device.c | 1 - drivers/gpu/drm/panfrost/panfrost_device.h | 6 +- drivers/gpu/drm/panfrost/panfrost_job.c | 127 ++++++++++++--------- 3 files changed, 79 insertions(+), 55 deletions(-)
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c index ea8d31863c50..a83b2ff5837a 100644 --- a/drivers/gpu/drm/panfrost/panfrost_device.c +++ b/drivers/gpu/drm/panfrost/panfrost_device.c @@ -200,7 +200,6 @@ int panfrost_device_init(struct panfrost_device *pfdev) struct resource *res; mutex_init(&pfdev->sched_lock);
- mutex_init(&pfdev->reset_lock); INIT_LIST_HEAD(&pfdev->scheduled_jobs); INIT_LIST_HEAD(&pfdev->as_lru_list);
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h index 140e004a3790..597cf1459b0a 100644 --- a/drivers/gpu/drm/panfrost/panfrost_device.h +++ b/drivers/gpu/drm/panfrost/panfrost_device.h @@ -106,7 +106,11 @@ struct panfrost_device { struct panfrost_perfcnt *perfcnt; struct mutex sched_lock;
- struct mutex reset_lock;
- struct {
struct work_struct work;atomic_t pending;- } reset;
struct mutex shrinker_lock; struct list_head shrinker_list; diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c index 4902bc6624c8..14c11293791e 100644 --- a/drivers/gpu/drm/panfrost/panfrost_job.c +++ b/drivers/gpu/drm/panfrost/panfrost_job.c @@ -20,6 +20,8 @@ #include "panfrost_gpu.h" #include "panfrost_mmu.h" +#define JOB_TIMEOUT_MS 500
- #define job_write(dev, reg, data) writel(data, dev->iomem + (reg)) #define job_read(dev, reg) readl(dev->iomem + (reg))
@@ -382,19 +384,37 @@ static bool panfrost_scheduler_stop(struct panfrost_queue_state *queue, drm_sched_increase_karma(bad); queue->stopped = true; stopped = true;
/** Set the timeout to max so the timer doesn't get started* when we return from the timeout handler (restored in* panfrost_scheduler_start()).*/queue->sched.timeout = MAX_SCHEDULE_TIMEOUT;return stopped; } +static void panfrost_scheduler_start(struct panfrost_queue_state *queue) +{
- if (WARN_ON(!queue->stopped))
return;- mutex_lock(&queue->lock);
- /* Restore the original timeout before starting the scheduler. */
- queue->sched.timeout = msecs_to_jiffies(JOB_TIMEOUT_MS);
- drm_sched_start(&queue->sched, true);
- queue->stopped = false;
- mutex_unlock(&queue->lock);
+}
- static void panfrost_job_timedout(struct drm_sched_job *sched_job) { struct panfrost_job *job = to_panfrost_job(sched_job); struct panfrost_device *pfdev = job->pfdev; int js = panfrost_job_get_slot(job);
- unsigned long flags;
- int i;
/* * If the GPU managed to complete this jobs fence, the timeout is @@ -415,56 +435,9 @@ static void panfrost_job_timedout(struct drm_sched_job *sched_job) if (!panfrost_scheduler_stop(&pfdev->js->queue[js], sched_job)) return;
- if (!mutex_trylock(&pfdev->reset_lock))
return;- for (i = 0; i < NUM_JOB_SLOTS; i++) {
struct drm_gpu_scheduler *sched = &pfdev->js->queue[i].sched;/** If the queue is still active, make sure we wait for any* pending timeouts.*/if (!pfdev->js->queue[i].stopped)cancel_delayed_work_sync(&sched->work_tdr);/** If the scheduler was not already stopped, there's a tiny* chance a timeout has expired just before we stopped it, and* drm_sched_stop() does not flush pending works. Let's flush* them now so the timeout handler doesn't get called in the* middle of a reset.*/if (panfrost_scheduler_stop(&pfdev->js->queue[i], NULL))cancel_delayed_work_sync(&sched->work_tdr);/** Now that we cancelled the pending timeouts, we can safely* reset the stopped state.*/pfdev->js->queue[i].stopped = false;- }
- spin_lock_irqsave(&pfdev->js->job_lock, flags);
- for (i = 0; i < NUM_JOB_SLOTS; i++) {
if (pfdev->jobs[i]) {pm_runtime_put_noidle(pfdev->dev);panfrost_devfreq_record_idle(&pfdev->pfdevfreq);pfdev->jobs[i] = NULL;}- }
- spin_unlock_irqrestore(&pfdev->js->job_lock, flags);
- panfrost_device_reset(pfdev);
- for (i = 0; i < NUM_JOB_SLOTS; i++)
drm_sched_resubmit_jobs(&pfdev->js->queue[i].sched);- mutex_unlock(&pfdev->reset_lock);
- /* restart scheduler after GPU is usable again */
- for (i = 0; i < NUM_JOB_SLOTS; i++)
drm_sched_start(&pfdev->js->queue[i].sched, true);
- /* Schedule a reset if there's no reset in progress. */
- if (!atomic_cmpxchg(&pfdev->reset.pending, 0, 1))
schedule_work(&pfdev->reset.work);static const struct drm_sched_backend_ops panfrost_sched_ops = { @@ -531,11 +504,59 @@ static irqreturn_t panfrost_job_irq_handler(int irq, void *data) return IRQ_HANDLED; } +static void panfrost_reset(struct work_struct *work) +{
- struct panfrost_device *pfdev = container_of(work,
struct panfrost_device,reset.work);- unsigned long flags;
- unsigned int i;
- for (i = 0; i < NUM_JOB_SLOTS; i++) {
/** We want pending timeouts to be handled before we attempt* to stop the scheduler. If we don't do that and the timeout* handler is in flight, it might have removed the bad job* from the list, and we'll lose this job if the reset handler* enters the critical section in panfrost_scheduler_stop()* before the timeout handler.** Timeout is set to max to make sure the timer is not* restarted after the cancellation.*/pfdev->js->queue[i].sched.timeout = MAX_SCHEDULE_TIMEOUT;cancel_delayed_work_sync(&pfdev->js->queue[i].sched.work_tdr);panfrost_scheduler_stop(&pfdev->js->queue[i], NULL);- }
- /* All timers have been stopped, we can safely reset the pending state. */
- atomic_set(&pfdev->reset.pending, 0);
- spin_lock_irqsave(&pfdev->js->job_lock, flags);
- for (i = 0; i < NUM_JOB_SLOTS; i++) {
if (pfdev->jobs[i]) {pm_runtime_put_noidle(pfdev->dev);panfrost_devfreq_record_idle(&pfdev->pfdevfreq);pfdev->jobs[i] = NULL;}- }
- spin_unlock_irqrestore(&pfdev->js->job_lock, flags);
- panfrost_device_reset(pfdev);
- for (i = 0; i < NUM_JOB_SLOTS; i++) {
drm_sched_resubmit_jobs(&pfdev->js->queue[i].sched);panfrost_scheduler_start(&pfdev->js->queue[i]);- }
+}
- int panfrost_job_init(struct panfrost_device *pfdev) { struct panfrost_job_slot *js; int ret, j, irq;
- INIT_WORK(&pfdev->reset.work, panfrost_reset);
- pfdev->js = js = devm_kzalloc(pfdev->dev, sizeof(*js), GFP_KERNEL); if (!js) return -ENOMEM;
@@ -560,7 +581,7 @@ int panfrost_job_init(struct panfrost_device *pfdev) ret = drm_sched_init(&js->queue[j].sched, &panfrost_sched_ops,
1, 0, msecs_to_jiffies(500),
1, 0, msecs_to_jiffies(JOB_TIMEOUT_MS), "pan_js");