linux-kernel - [PATCH AUTOSEL 6.6 03/21] Revert "drm/msm/gpu: Push gpu lock down past runpm"

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Message-ID: <20240229154946.2850012-3-sashal@kernel.org>
Date: Thu, 29 Feb 2024 10:49:23 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Rob Clark <robdclark@...omium.org>,
	Sasha Levin <sashal@...nel.org>,
	robdclark@...il.com,
	quic_abhinavk@...cinc.com,
	dmitry.baryshkov@...aro.org,
	airlied@...il.com,
	daniel@...ll.ch,
	linux-arm-msm@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	freedreno@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.6 03/21] Revert "drm/msm/gpu: Push gpu lock down past runpm"

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

[ Upstream commit 917e9b7c2350e3e53162fcf5035e5f2d68e2cbed ]

This reverts commit abe2023b4cea192ab266b351fd38dc9dbd846df0.

Changing the locking order means that scheduler/msm_job_run() can race
with the recovery kthread worker, with the result that the GPU gets an
extra runpm get when we are trying to power it off.  Leaving the GPU in
an unrecovered state.

I'll need to come up with a different scheme for appeasing lockdep.

Signed-off-by: Rob Clark <robdclark@...omium.org>
Patchwork: https://patchwork.freedesktop.org/patch/573835/
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/msm/msm_gpu.c        | 11 +++++------
 drivers/gpu/drm/msm/msm_ringbuffer.c |  7 +++++--
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 7f64c66673002..5c10b559a5957 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -749,12 +749,14 @@ void msm_gpu_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	struct msm_ringbuffer *ring = submit->ring;
 	unsigned long flags;
 
-	pm_runtime_get_sync(&gpu->pdev->dev);
+	WARN_ON(!mutex_is_locked(&gpu->lock));
 
-	mutex_lock(&gpu->lock);
+	pm_runtime_get_sync(&gpu->pdev->dev);
 
 	msm_gpu_hw_init(gpu);
 
+	submit->seqno = submit->hw_fence->seqno;
+
 	update_sw_cntrs(gpu);
 
 	/*
@@ -779,11 +781,8 @@ void msm_gpu_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	gpu->funcs->submit(gpu, submit);
 	gpu->cur_ctx_seqno = submit->queue->ctx->seqno;
 
-	hangcheck_timer_reset(gpu);
-
-	mutex_unlock(&gpu->lock);
-
 	pm_runtime_put(&gpu->pdev->dev);
+	hangcheck_timer_reset(gpu);
 }
 
 /*
diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.c b/drivers/gpu/drm/msm/msm_ringbuffer.c
index 40c0bc35a44ce..7f5e0a961bba7 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.c
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.c
@@ -21,8 +21,6 @@ static struct dma_fence *msm_job_run(struct drm_sched_job *job)
 
 	msm_fence_init(submit->hw_fence, fctx);
 
-	submit->seqno = submit->hw_fence->seqno;
-
 	mutex_lock(&priv->lru.lock);
 
 	for (i = 0; i < submit->nr_bos; i++) {
@@ -34,8 +32,13 @@ static struct dma_fence *msm_job_run(struct drm_sched_job *job)
 
 	mutex_unlock(&priv->lru.lock);
 
+	/* TODO move submit path over to using a per-ring lock.. */
+	mutex_lock(&gpu->lock);
+
 	msm_gpu_submit(gpu, submit);
 
+	mutex_unlock(&gpu->lock);
+
 	return dma_fence_get(submit->hw_fence);
 }
 
-- 
2.43.0