drm/panthor: Make the timeout per-queue instead of per-job

The timeout logic provided by drm_sched leads to races when we try to suspend it while the drm_sched workqueue queues more jobs. Let's overhaul the timeout handling in panthor to have our own delayed work that's resumed/suspended when a group is resumed/suspended. When an actual timeout occurs, we call drm_sched_fault() to report it through drm_sched, still. But otherwise, the drm_sched timeout is disabled (set to MAX_SCHEDULE_TIMEOUT), which leaves us in control of how we protect modifications on the timer. One issue seems to be when we call drm_sched_suspend_timeout() from both queue_run_job() and tick_work() which could lead to races due to drm_sched_suspend_timeout() not having a lock. Another issue seems to be in queue_run_job() if the group is not scheduled, we suspend the timeout again which undoes what drm_sched_job_begin() did when calling drm_sched_start_timeout(). So the timeout does not reset when a job is finished. v2: - Fix syntax error v3: - Split the changes in two commits v4: - No changes v5: - No changes v6: - Fix a NULL deref in group_can_run(), and narrow the group variable scope to avoid such mistakes in the future - Add an queue_timeout_is_suspended() helper to clarify things v7: - No changes v8: - Don't touch drm_gpu_scheduler::timeout in queue_timedout_job() Fixes: de85488138 ("drm/panthor: Add the scheduler logical block") Reviewed-by: Steven Price <steven.price@arm.com> Reviewed-by: Liviu Dudau <liviu.dudau@arm.com> Reviewed-by: Adrián Larumbe <adrian.larumbe@collabora.com> Signed-off-by: Ashley Smith <ashley.smith@collabora.com> Co-developed-by: Boris Brezillon <boris.brezillon@collabora.com> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com> Link: https://patch.msgid.link/20251113105734.1520338-2-boris.brezillon@collabora.com
2026-04-05 11:55:31 -04:00 · 2025-11-13 11:57:33 +01:00
parent 922682d48d
commit 345c5b7cc0
1 changed files with 201 additions and 80 deletions
--- a/drivers/gpu/drm/panthor/panthor_sched.c
+++ b/drivers/gpu/drm/panthor/panthor_sched.c
@@ -364,17 +364,20 @@ struct panthor_queue {
 	/** @name: DRM scheduler name for this queue. */
 	char *name;

-	/**
-	 * @remaining_time: Time remaining before the job timeout expires.
-	 *
-	 * The job timeout is suspended when the queue is not scheduled by the
-	 * FW. Every time we suspend the timer, we need to save the remaining
-	 * time so we can restore it later on.
-	 */
-	unsigned long remaining_time;
+	/** @timeout: Queue timeout related fields. */
+	struct {
+		/** @timeout.work: Work executed when a queue timeout occurs. */
+		struct delayed_work work;

-	/** @timeout_suspended: True if the job timeout was suspended. */
-	bool timeout_suspended;
+		/**
+		 * @timeout.remaining: Time remaining before a queue timeout.
+		 *
+		 * When the timer is running, this value is set to MAX_SCHEDULE_TIMEOUT.
+		 * When the timer is suspended, it's set to the time remaining when the
+		 * timer was suspended.
+		 */
+		unsigned long remaining;
+	} timeout;

 	/**
 	 * @doorbell_id: Doorbell assigned to this queue.
@@ -899,6 +902,10 @@ static void group_free_queue(struct panthor_group *group, struct panthor_queue *
 	if (IS_ERR_OR_NULL(queue))
 		return;

+	/* This should have been disabled before that point. */
+	drm_WARN_ON(&group->ptdev->base,
+		    disable_delayed_work_sync(&queue->timeout.work));
+
 	if (queue->entity.fence_context)
 		drm_sched_entity_destroy(&queue->entity);

@@ -1046,6 +1053,115 @@ group_unbind_locked(struct panthor_group *group)
 	return 0;
 }

+static bool
+group_is_idle(struct panthor_group *group)
+{
+	struct panthor_device *ptdev = group->ptdev;
+	u32 inactive_queues;
+
+	if (group->csg_id >= 0)
+		return ptdev->scheduler->csg_slots[group->csg_id].idle;
+
+	inactive_queues = group->idle_queues | group->blocked_queues;
+	return hweight32(inactive_queues) == group->queue_count;
+}
+
+static void
+queue_reset_timeout_locked(struct panthor_queue *queue)
+{
+	lockdep_assert_held(&queue->fence_ctx.lock);
+
+	if (queue->timeout.remaining != MAX_SCHEDULE_TIMEOUT) {
+		mod_delayed_work(queue->scheduler.timeout_wq,
+				 &queue->timeout.work,
+				 msecs_to_jiffies(JOB_TIMEOUT_MS));
+	}
+}
+
+static bool
+group_can_run(struct panthor_group *group)
+{
+	return group->state != PANTHOR_CS_GROUP_TERMINATED &&
+	       group->state != PANTHOR_CS_GROUP_UNKNOWN_STATE &&
+	       !group->destroyed && group->fatal_queues == 0 &&
+	       !group->timedout;
+}
+
+static bool
+queue_timeout_is_suspended(struct panthor_queue *queue)
+{
+	/* When running, the remaining time is set to MAX_SCHEDULE_TIMEOUT. */
+	return queue->timeout.remaining != MAX_SCHEDULE_TIMEOUT;
+}
+
+static void
+queue_suspend_timeout_locked(struct panthor_queue *queue)
+{
+	unsigned long qtimeout, now;
+	struct panthor_group *group;
+	struct panthor_job *job;
+	bool timer_was_active;
+
+	lockdep_assert_held(&queue->fence_ctx.lock);
+
+	/* Already suspended, nothing to do. */
+	if (queue_timeout_is_suspended(queue))
+		return;
+
+	job = list_first_entry_or_null(&queue->fence_ctx.in_flight_jobs,
+				       struct panthor_job, node);
+	group = job ? job->group : NULL;
+
+	/* If the queue is blocked and the group is idle, we want the timer to
+	 * keep running because the group can't be unblocked by other queues,
+	 * so it has to come from an external source, and we want to timebox
+	 * this external signalling.
+	 */
+	if (group && group_can_run(group) &&
+	    (group->blocked_queues & BIT(job->queue_idx)) &&
+	    group_is_idle(group))
+		return;
+
+	now = jiffies;
+	qtimeout = queue->timeout.work.timer.expires;
+
+	/* Cancel the timer. */
+	timer_was_active = cancel_delayed_work(&queue->timeout.work);
+	if (!timer_was_active || !job)
+		queue->timeout.remaining = msecs_to_jiffies(JOB_TIMEOUT_MS);
+	else if (time_after(qtimeout, now))
+		queue->timeout.remaining = qtimeout - now;
+	else
+		queue->timeout.remaining = 0;
+
+	if (WARN_ON_ONCE(queue->timeout.remaining > msecs_to_jiffies(JOB_TIMEOUT_MS)))
+		queue->timeout.remaining = msecs_to_jiffies(JOB_TIMEOUT_MS);
+}
+
+static void
+queue_suspend_timeout(struct panthor_queue *queue)
+{
+	spin_lock(&queue->fence_ctx.lock);
+	queue_suspend_timeout_locked(queue);
+	spin_unlock(&queue->fence_ctx.lock);
+}
+
+static void
+queue_resume_timeout(struct panthor_queue *queue)
+{
+	spin_lock(&queue->fence_ctx.lock);
+
+	if (queue_timeout_is_suspended(queue)) {
+		mod_delayed_work(queue->scheduler.timeout_wq,
+				 &queue->timeout.work,
+				 queue->timeout.remaining);
+
+		queue->timeout.remaining = MAX_SCHEDULE_TIMEOUT;
+	}
+
+	spin_unlock(&queue->fence_ctx.lock);
+}
+
 /**
 * cs_slot_prog_locked() - Program a queue slot
 * @ptdev: Device.
@@ -1084,10 +1200,8 @@ cs_slot_prog_locked(struct panthor_device *ptdev, u32 csg_id, u32 cs_id)
 			       CS_IDLE_EMPTY |
 			       CS_STATE_MASK |
 			       CS_EXTRACT_EVENT);
-	if (queue->iface.input->insert != queue->iface.input->extract && queue->timeout_suspended) {
-		drm_sched_resume_timeout(&queue->scheduler, queue->remaining_time);
-		queue->timeout_suspended = false;
-	}
+	if (queue->iface.input->insert != queue->iface.input->extract)
+		queue_resume_timeout(queue);
 }

 /**
@@ -1114,14 +1228,7 @@ cs_slot_reset_locked(struct panthor_device *ptdev, u32 csg_id, u32 cs_id)
 			       CS_STATE_STOP,
 			       CS_STATE_MASK);

-	/* If the queue is blocked, we want to keep the timeout running, so
-	 * we can detect unbounded waits and kill the group when that happens.
-	 */
-	if (!(group->blocked_queues & BIT(cs_id)) && !queue->timeout_suspended) {
-		queue->remaining_time = drm_sched_suspend_timeout(&queue->scheduler);
-		queue->timeout_suspended = true;
-		WARN_ON(queue->remaining_time > msecs_to_jiffies(JOB_TIMEOUT_MS));
-	}
+	queue_suspend_timeout(queue);

 	return 0;
 }
@@ -1921,28 +2028,6 @@ tick_ctx_is_full(const struct panthor_scheduler *sched,
 	return ctx->group_count == sched->csg_slot_count;
 }

-static bool
-group_is_idle(struct panthor_group *group)
-{
-	struct panthor_device *ptdev = group->ptdev;
-	u32 inactive_queues;
-
-	if (group->csg_id >= 0)
-		return ptdev->scheduler->csg_slots[group->csg_id].idle;
-
-	inactive_queues = group->idle_queues | group->blocked_queues;
-	return hweight32(inactive_queues) == group->queue_count;
-}
-
-static bool
-group_can_run(struct panthor_group *group)
-{
-	return group->state != PANTHOR_CS_GROUP_TERMINATED &&
-	       group->state != PANTHOR_CS_GROUP_UNKNOWN_STATE &&
-	       !group->destroyed && group->fatal_queues == 0 &&
-	       !group->timedout;
-}
-
 static void
 tick_ctx_pick_groups_from_list(const struct panthor_scheduler *sched,
 			       struct panthor_sched_tick_ctx *ctx,
@@ -2624,6 +2709,7 @@ static void group_schedule_locked(struct panthor_group *group, u32 queue_mask)
 static void queue_stop(struct panthor_queue *queue,
 		       struct panthor_job *bad_job)
 {
+	disable_delayed_work_sync(&queue->timeout.work);
 	drm_sched_stop(&queue->scheduler, bad_job ? &bad_job->base : NULL);
 }

@@ -2635,6 +2721,7 @@ static void queue_start(struct panthor_queue *queue)
 	list_for_each_entry(job, &queue->scheduler.pending_list, base.list)
 		job->base.s_fence->parent = dma_fence_get(job->done_fence);

+	enable_delayed_work(&queue->timeout.work);
 	drm_sched_start(&queue->scheduler, 0);
 }

@@ -2701,7 +2788,6 @@ void panthor_sched_suspend(struct panthor_device *ptdev)
 {
 	struct panthor_scheduler *sched = ptdev->scheduler;
 	struct panthor_csg_slots_upd_ctx upd_ctx;
-	struct panthor_group *group;
 	u32 suspended_slots;
 	u32 i;

@@ -2791,8 +2877,8 @@ void panthor_sched_suspend(struct panthor_device *ptdev)

 	for (i = 0; i < sched->csg_slot_count; i++) {
 		struct panthor_csg_slot *csg_slot = &sched->csg_slots[i];
+		struct panthor_group *group = csg_slot->group;

-		group = csg_slot->group;
 		if (!group)
 			continue;

@@ -2921,35 +3007,47 @@ void panthor_fdinfo_gather_group_samples(struct panthor_file *pfile)
 	xa_unlock(&gpool->xa);
 }

-static void group_sync_upd_work(struct work_struct *work)
+static bool queue_check_job_completion(struct panthor_queue *queue)
 {
-	struct panthor_group *group =
-		container_of(work, struct panthor_group, sync_upd_work);
+	struct panthor_syncobj_64b *syncobj = NULL;
 	struct panthor_job *job, *job_tmp;
+	bool cookie, progress = false;
 	LIST_HEAD(done_jobs);
-	u32 queue_idx;
-	bool cookie;

 	cookie = dma_fence_begin_signalling();
-	for (queue_idx = 0; queue_idx < group->queue_count; queue_idx++) {
-		struct panthor_queue *queue = group->queues[queue_idx];
-		struct panthor_syncobj_64b *syncobj;
+	spin_lock(&queue->fence_ctx.lock);
+	list_for_each_entry_safe(job, job_tmp, &queue->fence_ctx.in_flight_jobs, node) {
+		if (!syncobj) {
+			struct panthor_group *group = job->group;

-		if (!queue)
-			continue;
-
-		syncobj = group->syncobjs->kmap + (queue_idx * sizeof(*syncobj));
-
-		spin_lock(&queue->fence_ctx.lock);
-		list_for_each_entry_safe(job, job_tmp, &queue->fence_ctx.in_flight_jobs, node) {
-			if (syncobj->seqno < job->done_fence->seqno)
-				break;
-
-			list_move_tail(&job->node, &done_jobs);
-			dma_fence_signal_locked(job->done_fence);
+			syncobj = group->syncobjs->kmap +
+				  (job->queue_idx * sizeof(*syncobj));
 		}
-		spin_unlock(&queue->fence_ctx.lock);
+
+		if (syncobj->seqno < job->done_fence->seqno)
+			break;
+
+		list_move_tail(&job->node, &done_jobs);
+		dma_fence_signal_locked(job->done_fence);
 	}
+
+	if (list_empty(&queue->fence_ctx.in_flight_jobs)) {
+		/* If we have no job left, we cancel the timer, and reset remaining
+		 * time to its default so it can be restarted next time
+		 * queue_resume_timeout() is called.
+		 */
+		queue_suspend_timeout_locked(queue);
+
+		/* If there's no job pending, we consider it progress to avoid a
+		 * spurious timeout if the timeout handler and the sync update
+		 * handler raced.
+		 */
+		progress = true;
+	} else if (!list_empty(&done_jobs)) {
+		queue_reset_timeout_locked(queue);
+		progress = true;
+	}
+	spin_unlock(&queue->fence_ctx.lock);
 	dma_fence_end_signalling(cookie);

 	list_for_each_entry_safe(job, job_tmp, &done_jobs, node) {
@@ -2959,6 +3057,27 @@ static void group_sync_upd_work(struct work_struct *work)
 		panthor_job_put(&job->base);
 	}

+	return progress;
+}
+
+static void group_sync_upd_work(struct work_struct *work)
+{
+	struct panthor_group *group =
+		container_of(work, struct panthor_group, sync_upd_work);
+	u32 queue_idx;
+	bool cookie;
+
+	cookie = dma_fence_begin_signalling();
+	for (queue_idx = 0; queue_idx < group->queue_count; queue_idx++) {
+		struct panthor_queue *queue = group->queues[queue_idx];
+
+		if (!queue)
+			continue;
+
+		queue_check_job_completion(queue);
+	}
+	dma_fence_end_signalling(cookie);
+
 	group_put(group);
 }

@@ -3206,17 +3325,6 @@ queue_run_job(struct drm_sched_job *sched_job)
 	queue->iface.input->insert = job->ringbuf.end;

 	if (group->csg_id < 0) {
-		/* If the queue is blocked, we want to keep the timeout running, so we
-		 * can detect unbounded waits and kill the group when that happens.
-		 * Otherwise, we suspend the timeout so the time we spend waiting for
-		 * a CSG slot is not counted.
-		 */
-		if (!(group->blocked_queues & BIT(job->queue_idx)) &&
-		    !queue->timeout_suspended) {
-			queue->remaining_time = drm_sched_suspend_timeout(&queue->scheduler);
-			queue->timeout_suspended = true;
-		}
-
 		group_schedule_locked(group, BIT(job->queue_idx));
 	} else {
 		gpu_write(ptdev, CSF_DOORBELL(queue->doorbell_id), 1);
@@ -3225,6 +3333,7 @@ queue_run_job(struct drm_sched_job *sched_job)
 			pm_runtime_get(ptdev->base.dev);
 			sched->pm.has_ref = true;
 		}
+		queue_resume_timeout(queue);
 		panthor_devfreq_record_busy(sched->ptdev);
 	}

@@ -3274,7 +3383,6 @@ queue_timedout_job(struct drm_sched_job *sched_job)
 	mutex_unlock(&sched->lock);

 	queue_start(queue);
-
 	return DRM_GPU_SCHED_STAT_RESET;
 }

@@ -3317,6 +3425,17 @@ static u32 calc_profiling_ringbuf_num_slots(struct panthor_device *ptdev,
 	return DIV_ROUND_UP(cs_ringbuf_size, min_profiled_job_instrs * sizeof(u64));
 }

+static void queue_timeout_work(struct work_struct *work)
+{
+	struct panthor_queue *queue = container_of(work, struct panthor_queue,
+						   timeout.work.work);
+	bool progress;
+
+	progress = queue_check_job_completion(queue);
+	if (!progress)
+		drm_sched_fault(&queue->scheduler);
+}
+
 static struct panthor_queue *
 group_create_queue(struct panthor_group *group,
 		   const struct drm_panthor_queue_create *args,
@@ -3333,7 +3452,7 @@ group_create_queue(struct panthor_group *group,
 		 * their profiling status.
 		 */
 		.credit_limit = args->ringbuf_size / sizeof(u64),
-		.timeout = msecs_to_jiffies(JOB_TIMEOUT_MS),
+		.timeout = MAX_SCHEDULE_TIMEOUT,
 		.timeout_wq = group->ptdev->reset.wq,
 		.dev = group->ptdev->base.dev,
 	};
@@ -3355,6 +3474,8 @@ group_create_queue(struct panthor_group *group,
 	if (!queue)
 		return ERR_PTR(-ENOMEM);

+	queue->timeout.remaining = msecs_to_jiffies(JOB_TIMEOUT_MS);
+	INIT_DELAYED_WORK(&queue->timeout.work, queue_timeout_work);
 	queue->fence_ctx.id = dma_fence_context_alloc(1);
 	spin_lock_init(&queue->fence_ctx.lock);
 	INIT_LIST_HEAD(&queue->fence_ctx.in_flight_jobs);