drm/scheduler: Set sched->thread to NULL on failure

This patch adds two new functions to help client drivers suspend and resume the scheduler job timeout. This can be useful in cases where the hardware has preemption support enabled. Using this, it is possible to have the timeout active only for the ring which is active on the ringbuffer. This patch also makes the job_list_lock IRQ safe.

Suggested-by Christian Koenig <[email protected]>

Signed-off-by Sharat Masetty <[email protected]>

---
  drivers/gpu/drm/etnaviv/etnaviv_dump.c |  9 ++--
  drivers/gpu/drm/scheduler/sched_main.c | 91 ++++++++++++++++++++++++++++------
  include/drm/gpu_scheduler.h            |  4 ++
  3 files changed, 86 insertions(+), 18 deletions(-)

drivers/gpu/drm/etnaviv/etnaviv_dump.c +5 -4

index 9146e30..fd6bad2 100644
@@ -118,6 +118,7 @@ void etnaviv_core_dump(struct etnaviv_gpu *gpu)
  	unsigned int n_obj, n_bomap_pages;
  	size_t file_size, mmu_size;
  	__le64 *bomap, *bomap_start;
+	unsigned long flags;
 
  	/* Only catch the first event, or when manually re-armed */
  	if (!etnaviv_dump_core)

@@ -134,13 +135,13 @@ void etnaviv_core_dump(struct etnaviv_gpu *gpu)
  		    mmu_size + gpu->buffer.size;
 
  	/* Add in the active command buffers */
-	spin_lock(&gpu->sched.job_list_lock);
+	spin_lock_irqsave(&sched->job_list_lock, flags);
  	list_for_each_entry(s_job, &gpu->sched.ring_mirror_list, node) {
  		submit = to_etnaviv_submit(s_job);
  		file_size += submit->cmdbuf.size;
  		n_obj++;
  	}
-	spin_unlock(&gpu->sched.job_list_lock);
+	spin_unlock_irqrestore(&sched->job_list_lock, flags);
 
  	/* Add in the active buffer objects */
  	list_for_each_entry(vram, &gpu->mmu->mappings, mmu_node) {

@@ -182,14 +183,14 @@ void etnaviv_core_dump(struct etnaviv_gpu *gpu)
  			      gpu->buffer.size,
  			      etnaviv_cmdbuf_get_va(&gpu->buffer));
 
-	spin_lock(&gpu->sched.job_list_lock);
+	spin_lock_irqsave(&sched->job_list_lock, flags);
  	list_for_each_entry(s_job, &gpu->sched.ring_mirror_list, node) {
  		submit = to_etnaviv_submit(s_job);
  		etnaviv_core_dump_mem(&iter, ETDUMP_BUF_CMD,
  				      submit->cmdbuf.vaddr, submit->cmdbuf.size,
  				      etnaviv_cmdbuf_get_va(&submit->cmdbuf));
  	}
-	spin_unlock(&gpu->sched.job_list_lock);
+	spin_unlock_irqrestore(&sched->job_list_lock, flags);
 
  	/* Reserve space for the bomap */
  	if (n_bomap_pages) {

drivers/gpu/drm/scheduler/sched_main.c +77 -14

index c993d10..ca09b4e 100644
@@ -196,10 +196,68 @@ static void drm_sched_start_timeout(struct drm_gpu_scheduler *sched)
  		schedule_delayed_work(&sched->work_tdr, sched->timeout);
  }
 
+/**
+ * drm_sched_suspend_timeout - Suspend scheduler job timeout
+ *
+ * @sched: scheduler instance for which to suspend the timeout
+ *
+ * Suspend the delayed work timeout for the scheduler. This is done by
+ * modifying the delayed work timeout to an arbitrary large value,
+ * MAX_SCHEDULE_TIMEOUT in this case. Note that this function can be
+ * called from an IRQ context.
+ *
+ * Returns the timeout remaining
+ *
+ */
+unsigned long drm_sched_suspend_timeout(struct drm_gpu_scheduler *sched)
+{
+	unsigned long sched_timeout, now = jiffies;
+
+	sched_timeout = sched->work_tdr.timer.expires;
+
+	/*
+	 * Modify the timeout to an arbitrarily large value. This also prevents
+	 * the timeout to be restarted when new submissions arrive
+	 */
+	if (mod_delayed_work(system_wq, &sched->work_tdr, MAX_SCHEDULE_TIMEOUT)
+			&& time_after(sched_timeout, now))
+		return sched_timeout - now;
+	else
+		return sched->timeout;
+}
+EXPORT_SYMBOL(drm_sched_suspend_timeout);
+
+/**
+ * drm_sched_resume_timeout - Resume scheduler job timeout
+ *
+ * @sched: scheduler instance for which to resume the timeout
+ * @remaining: remaining timeout
+ *
+ * Resume the delayed work timeout for the scheduler. Note that
+ * this function can be called from an IRQ context.
+ */
+void drm_sched_resume_timeout(struct drm_gpu_scheduler *sched,
+		unsigned long remaining)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&sched->job_list_lock, flags);
+
+	if (list_empty(&sched->ring_mirror_list))
+		cancel_delayed_work(&sched->work_tdr);
+	else
+		mod_delayed_work(system_wq, &sched->work_tdr, remaining);
+
+	spin_unlock_irqrestore(&sched->job_list_lock, flags);
+}
+EXPORT_SYMBOL(drm_sched_resume_timeout);
+
  /* job_finish is called after hw fence signaled
   */
  static void drm_sched_job_finish(struct work_struct *work)
  {
+	unsigned long flags;
+
  	struct drm_sched_job *s_job = container_of(work, struct drm_sched_job,
  						   finish_work);
  	struct drm_gpu_scheduler *sched = s_job->sched;

@@ -213,12 +271,12 @@ static void drm_sched_job_finish(struct work_struct *work)
  	 */
  	cancel_delayed_work_sync(&sched->work_tdr);
 
-	spin_lock(&sched->job_list_lock);
+	spin_lock_irqsave(&sched->job_list_lock, flags);
  	/* remove job from ring_mirror_list */
  	list_del(&s_job->node);
  	/* queue TDR for next job */
  	drm_sched_start_timeout(sched);
-	spin_unlock(&sched->job_list_lock);
+	spin_unlock_irqrestore(&sched->job_list_lock, flags);
 
  	dma_fence_put(&s_job->s_fence->finished);
  	sched->ops->free_job(s_job);

@@ -234,15 +292,17 @@ static void drm_sched_job_finish_cb(struct dma_fence *f,
 
  static void drm_sched_job_begin(struct drm_sched_job *s_job)
  {
+	unsigned long flags;
+
  	struct drm_gpu_scheduler *sched = s_job->sched;
 
  	dma_fence_add_callback(&s_job->s_fence->finished, &s_job->finish_cb,
  			       drm_sched_job_finish_cb);
 
-	spin_lock(&sched->job_list_lock);
+	spin_lock_irqsave(&sched->job_list_lock, flags);
  	list_add_tail(&s_job->node, &sched->ring_mirror_list);
  	drm_sched_start_timeout(sched);
-	spin_unlock(&sched->job_list_lock);
+	spin_unlock_irqrestore(&sched->job_list_lock, flags);
  }
 
  static void drm_sched_job_timedout(struct work_struct *work)

@@ -250,10 +310,11 @@ static void drm_sched_job_timedout(struct work_struct *work)
  	struct drm_gpu_scheduler *sched;
  	struct drm_sched_job *job;
  	int r;
+	unsigned long flags;
 
  	sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
 
-	spin_lock(&sched->job_list_lock);
+	spin_lock_irqsave(&sched->job_list_lock, flags);
  	list_for_each_entry_reverse(job, &sched->ring_mirror_list, node) {
  		struct drm_sched_fence *fence = job->s_fence;
 

@@ -263,12 +324,12 @@ static void drm_sched_job_timedout(struct work_struct *work)
 
  	job = list_first_entry_or_null(&sched->ring_mirror_list,
  				       struct drm_sched_job, node);
-	spin_unlock(&sched->job_list_lock);
+	spin_unlock_irqrestore(&sched->job_list_lock, flags);
 
  	if (job)
  		sched->ops->timedout_job(job);
 
-	spin_lock(&sched->job_list_lock);
+	spin_lock_irqsave(&sched->job_list_lock, flags);
  	list_for_each_entry(job, &sched->ring_mirror_list, node) {
  		struct drm_sched_fence *fence = job->s_fence;
 

@@ -283,7 +344,7 @@ static void drm_sched_job_timedout(struct work_struct *work)
  already_signaled:
  		;
  	}
-	spin_unlock(&sched->job_list_lock);
+	spin_unlock_irqrestore(&sched->job_list_lock, flags);
  }
 
  /**

@@ -298,8 +359,9 @@ void drm_sched_hw_job_reset(struct drm_gpu_scheduler *sched, struct drm_sched_jo
  	struct drm_sched_job *s_job;
  	struct drm_sched_entity *entity, *tmp;
  	int i;
+	unsigned long flags;
 
-	spin_lock(&sched->job_list_lock);
+	spin_lock_irqsave(&sched->job_list_lock, flags);
  	list_for_each_entry_reverse(s_job, &sched->ring_mirror_list, node) {
  		if (s_job->s_fence->parent &&
  		    dma_fence_remove_callback(s_job->s_fence->parent,

@@ -309,7 +371,7 @@ void drm_sched_hw_job_reset(struct drm_gpu_scheduler *sched, struct drm_sched_jo
  			atomic_dec(&sched->hw_rq_count);
  		}
  	}
-	spin_unlock(&sched->job_list_lock);
+	spin_unlock_irqrestore(&sched->job_list_lock, flags);
 
  	if (bad && bad->s_priority != DRM_SCHED_PRIORITY_KERNEL) {
  		atomic_inc(&bad->karma);

@@ -348,8 +410,9 @@ void drm_sched_job_recovery(struct drm_gpu_scheduler *sched)
  	struct drm_sched_job *s_job, *tmp;
  	bool found_guilty = false;
  	int r;
+	unsigned long flags;
 
-	spin_lock(&sched->job_list_lock);
+	spin_lock_irqsave(&sched->job_list_lock, flags);
  	list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list, node) {
  		struct drm_sched_fence *s_fence = s_job->s_fence;
  		struct dma_fence *fence;

@@ -363,7 +426,7 @@ void drm_sched_job_recovery(struct drm_gpu_scheduler *sched)
  		if (found_guilty && s_job->s_fence->scheduled.context == guilty_context)
  			dma_fence_set_error(&s_fence->finished, -ECANCELED);
 
-		spin_unlock(&sched->job_list_lock);
+		spin_unlock_irqrestore(&sched->job_list_lock, flags);
  		fence = sched->ops->run_job(s_job);
  		atomic_inc(&sched->hw_rq_count);
 

@@ -380,10 +443,10 @@ void drm_sched_job_recovery(struct drm_gpu_scheduler *sched)
  		} else {
  			drm_sched_process_job(NULL, &s_fence->cb);
  		}
-		spin_lock(&sched->job_list_lock);
+		spin_lock_irqsave(&sched->job_list_lock, flags);
  	}
  	drm_sched_start_timeout(sched);
-	spin_unlock(&sched->job_list_lock);
+	spin_unlock_irqrestore(&sched->job_list_lock, flags);
  }
  EXPORT_SYMBOL(drm_sched_job_recovery);
 

include/drm/gpu_scheduler.h +0 -0

index d87b268..c9657a8 100644

In cases where the scheduler instance is used as a base object of another driver object, it's not clear if the driver can call scheduler cleanup on the fail path. So, Set the sched->thread to NULL, so that the driver can safely call drm_sched_fini() during cleanup.

Signed-off-by Sharat Masetty <[email protected]>

---
  drivers/gpu/drm/scheduler/sched_main.c | 6 ++++--
  1 file changed, 4 insertions(+), 2 deletions(-)

drivers/gpu/drm/scheduler/sched_main.c +1 -1

index 44fe587..c993d10 100644
@@ -594,7 +594,7 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
  		   long timeout,
  		   const char *name)
  {
-	int i;
+	int i, ret;
  	sched->ops = ops;
  	sched->hw_submission_limit = hw_submission;
  	sched->name = name;

@@ -615,8 +615,10 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
  	/* Each scheduler will run on a seperate kernel thread */