linux-kernel - [PATCH 1/2] drm/msm: Move hangcheck timer restart

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Message-Id: <20220803172302.1976981-1-robdclark@gmail.com>
Date:   Wed,  3 Aug 2022 10:23:01 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        Rob Clark <robdclark@...omium.org>,
        Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/2] drm/msm: Move hangcheck timer restart

From: Rob Clark <robdclark@...omium.org>

Don't directly restart the hangcheck timer from the timer handler, but
instead start it after the recover_worker replays remaining jobs.

If the kthread is blocked for other reasons, there is no point to
immediately restart the timer.  Fixes a random symptom of the problem
fixed in the next patch.

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/msm/msm_gpu.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index fba85f894314..8f9c48eabf7d 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -328,6 +328,7 @@ find_submit(struct msm_ringbuffer *ring, uint32_t fence)
 }
 
 static void retire_submits(struct msm_gpu *gpu);
+static void hangcheck_timer_reset(struct msm_gpu *gpu);
 
 static void get_comm_cmdline(struct msm_gem_submit *submit, char **comm, char **cmd)
 {
@@ -420,6 +421,8 @@ static void recover_worker(struct kthread_work *work)
 	}
 
 	if (msm_gpu_active(gpu)) {
+		bool restart_hangcheck = false;
+
 		/* retire completed submits, plus the one that hung: */
 		retire_submits(gpu);
 
@@ -436,10 +439,15 @@ static void recover_worker(struct kthread_work *work)
 			unsigned long flags;
 
 			spin_lock_irqsave(&ring->submit_lock, flags);
-			list_for_each_entry(submit, &ring->submits, node)
+			list_for_each_entry(submit, &ring->submits, node) {
 				gpu->funcs->submit(gpu, submit);
+				restart_hangcheck = true;
+			}
 			spin_unlock_irqrestore(&ring->submit_lock, flags);
 		}
+
+		if (restart_hangcheck)
+			hangcheck_timer_reset(gpu);
 	}
 
 	mutex_unlock(&gpu->lock);
@@ -515,10 +523,6 @@ static void hangcheck_handler(struct timer_list *t)
 		kthread_queue_work(gpu->worker, &gpu->recover_work);
 	}
 
-	/* if still more pending work, reset the hangcheck timer: */
-	if (fence_after(ring->fctx->last_fence, ring->hangcheck_fence))
-		hangcheck_timer_reset(gpu);
-
 	/* workaround for missing irq: */
 	msm_gpu_retire(gpu);
 }
-- 
2.36.1