[2/3] drm/v3d: Correctly restart the timer when progress is made

Commit Message

Yukimasa Sugizaki Sept. 4, 2020, 8:15 a.m. UTC

The V3D scheduler wants a timed-out job to continue running if it made
progress.  However, the current DRM scheduler removes the timed-out job
from ring_mirror_list and thus the timer is not restarted automatically,
resulting in an infinite timeout.  We need stop and restart the DRM
scheduler to rearm the timer.

Fixes: 135517d3565b ("drm/scheduler: Avoid accessing freed bad job.")
Signed-off-by: Yukimasa Sugizaki <[e-mail]>
---
 drivers/gpu/drm/v3d/v3d_sched.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

--
2.7.4

Patch

diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
index 001216f22017..feef0c749e68 100644
--- a/drivers/gpu/drm/v3d/v3d_sched.c
+++ b/drivers/gpu/drm/v3d/v3d_sched.c
@@ -312,9 +312,24 @@  v3d_cl_job_timedout(struct drm_sched_job *sched_job, enum v3d_queue q,
 	u32 ctca = V3D_CORE_READ(0, V3D_CLE_CTNCA(q));
 	u32 ctra = V3D_CORE_READ(0, V3D_CLE_CTNRA(q));

+	/* If we've made progress, skip reset and let the timer get
+	 * rearmed.
+	 */
 	if (*timedout_ctca != ctca || *timedout_ctra != ctra) {
 		*timedout_ctca = ctca;
 		*timedout_ctra = ctra;
+
+		/* Because the timed-out job has been removed from
+		 * ring_mirror_list in drm_sched_job_timedout(), we need to
+		 * stop and restart the scheduler to rearm the timer.
+		 * Holding the reset_lock is necessary for concurrent
+		 * v3d_gpu_reset_for_timeout().
+		 */
+		mutex_lock(&v3d->reset_lock);
+		drm_sched_stop(sched_job->sched, sched_job);
+		drm_sched_start(sched_job->sched, sched_job);
+		mutex_unlock(&v3d->reset_lock);
+
 		return;
 	}

@@ -359,6 +374,18 @@  v3d_csd_job_timedout(struct drm_sched_job *sched_job)
 	 */
 	if (job->timedout_batches != batches) {
 		job->timedout_batches = batches;
+
+		/* Because the timed-out job has been removed from
+		 * ring_mirror_list in drm_sched_job_timedout(), we need to
+		 * stop and restart the scheduler to rearm the timer.
+		 * Holding the reset_lock is necessary for concurrent
+		 * v3d_gpu_reset_for_timeout().
+		 */
+		mutex_lock(&v3d->reset_lock);
+		drm_sched_stop(sched_job->sched, sched_job);
+		drm_sched_start(sched_job->sched, sched_job);
+		mutex_unlock(&v3d->reset_lock);
+
 		return;
 	}