linux-kernel - [PATCH v2 1/2] drm/msm: Drop update

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Message-Id: <20220618161120.3451993-1-robdclark@gmail.com>
Date:   Sat, 18 Jun 2022 09:11:18 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Rob Clark <robdclark@...omium.org>,
        Steev Klimaszewski <steev@...i.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 v2 1/2] drm/msm: Drop update_fences()

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

I noticed while looking at some traces, that we could miss calls to
msm_update_fence(), as the irq could have raced with retire_submits()
which could have already popped the last submit on a ring out of the
queue of in-flight submits.  But walking the list of submits in the
irq handler isn't really needed, as dma_fence_is_signaled() will dtrt.
So lets just drop it entirely.

v2: use spin_lock_irqsave/restore as we are no longer protected by the
    spin_lock_irqsave/restore() in update_fences()

Reported-by: Steev Klimaszewski <steev@...i.org>
Fixes: 95d1deb02a9c ("drm/msm/gem: Add fenced vma unpin")
Signed-off-by: Rob Clark <robdclark@...omium.org>
Tested-by: Steev Klimaszewski <steev@...i.org>
---
 drivers/gpu/drm/msm/msm_fence.c |  8 +++++---
 drivers/gpu/drm/msm/msm_gpu.c   | 22 ++--------------------
 2 files changed, 7 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_fence.c b/drivers/gpu/drm/msm/msm_fence.c
index 3df255402a33..38e3323bc232 100644
--- a/drivers/gpu/drm/msm/msm_fence.c
+++ b/drivers/gpu/drm/msm/msm_fence.c
@@ -46,12 +46,14 @@ bool msm_fence_completed(struct msm_fence_context *fctx, uint32_t fence)
 		(int32_t)(*fctx->fenceptr - fence) >= 0;
 }
 
-/* called from workqueue */
+/* called from irq handler and workqueue (in recover path) */
 void msm_update_fence(struct msm_fence_context *fctx, uint32_t fence)
 {
-	spin_lock(&fctx->spinlock);
+	unsigned long flags;
+
+	spin_lock_irqsave(&fctx->spinlock, flags);
 	fctx->completed_fence = max(fence, fctx->completed_fence);
-	spin_unlock(&fctx->spinlock);
+	spin_unlock_irqrestore(&fctx->spinlock, flags);
 }
 
 struct msm_fence {
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 244511f85044..cedc88cf8083 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -164,24 +164,6 @@ int msm_gpu_hw_init(struct msm_gpu *gpu)
 	return ret;
 }
 
-static void update_fences(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
-		uint32_t fence)
-{
-	struct msm_gem_submit *submit;
-	unsigned long flags;
-
-	spin_lock_irqsave(&ring->submit_lock, flags);
-	list_for_each_entry(submit, &ring->submits, node) {
-		if (fence_after(submit->seqno, fence))
-			break;
-
-		msm_update_fence(submit->ring->fctx,
-			submit->hw_fence->seqno);
-		dma_fence_signal(submit->hw_fence);
-	}
-	spin_unlock_irqrestore(&ring->submit_lock, flags);
-}
-
 #ifdef CONFIG_DEV_COREDUMP
 static ssize_t msm_gpu_devcoredump_read(char *buffer, loff_t offset,
 		size_t count, void *data, size_t datalen)
@@ -438,7 +420,7 @@ static void recover_worker(struct kthread_work *work)
 		if (ring == cur_ring)
 			fence++;
 
-		update_fences(gpu, ring, fence);
+		msm_update_fence(ring->fctx, fence);
 	}
 
 	if (msm_gpu_active(gpu)) {
@@ -736,7 +718,7 @@ void msm_gpu_retire(struct msm_gpu *gpu)
 	int i;
 
 	for (i = 0; i < gpu->nr_rings; i++)
-		update_fences(gpu, gpu->rb[i], gpu->rb[i]->memptrs->fence);
+		msm_update_fence(gpu->rb[i]->fctx, gpu->rb[i]->memptrs->fence);
 
 	kthread_queue_work(gpu->worker, &gpu->retire_work);
 	update_sw_cntrs(gpu);
-- 
2.36.1