linux-kernel - [PATCH v2 02/23] drm/msm: Move submit bo flags update from obj lock

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Message-Id: <20230320144356.803762-3-robdclark@gmail.com>
Date:   Mon, 20 Mar 2023 07:43:24 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Daniel Vetter <daniel@...ll.ch>, freedreno@...ts.freedesktop.org,
        linux-arm-msm@...r.kernel.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@...il.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2 02/23] drm/msm: Move submit bo flags update from obj lock

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

The flags are only accessed (1) when submit is constructed, before
enqueuing to gpu sched (ie. when still visible to only the task calling
the submit ioctl), (2) here, where we own a reference to the submit and
are serialized on the gpu sched thread, and (3) after the submit is
retired and last reference is dropped, which is serialized on the
submit's reference count.  Hence locking is unneeded here.

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/msm/msm_ringbuffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.c b/drivers/gpu/drm/msm/msm_ringbuffer.c
index a62b45e5a8c3..a80447c8764e 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.c
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.c
@@ -26,8 +26,8 @@ static struct dma_fence *msm_job_run(struct drm_sched_job *job)
 		msm_gem_lock(obj);
 		msm_gem_unpin_vma_fenced(submit->bos[i].vma, fctx);
 		msm_gem_unpin_locked(obj);
-		submit->bos[i].flags &= ~(BO_VMA_PINNED | BO_OBJ_PINNED);
 		msm_gem_unlock(obj);
+		submit->bos[i].flags &= ~(BO_VMA_PINNED | BO_OBJ_PINNED);
 	}
 
 	/* TODO move submit path over to using a per-ring lock.. */
-- 
2.39.2