linux-kernel - [PATCH V4] amdgpu: reduce no need mutex

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Date:   Tue, 21 Apr 2020 00:36:21 -0700
From:   Bernard Zhao <bernard@...o.com>
To:     Felix Kuehling <Felix.Kuehling@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "David (ChunMing) Zhou" <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     opensource.kernel@...o.com, Bernard Zhao <bernard@...o.com>
Subject: [PATCH V4] amdgpu: reduce no need mutex_lock area

Maybe we could reduce the mutex_lock(&mem->lock)`s protected code area,
and no need to protect pr_debug.

Signed-off-by: Bernard Zhao <bernard@...o.com>

Changes since V1:
*commit message improve

Changes since V2:
*move comment along with the mutex_unlock

Changes since V3:
*lock protect the if check, there is some possibility of multi-threaded
 racing modify.

Link for V1:
*https://lore.kernel.org/patchwork/patch/1226588/
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 327317c54f7c..549bdb429883 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -1289,9 +1289,9 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
 	mutex_lock(&mem->lock);
 
 	if (mem->mapped_to_gpu_memory > 0) {
+		mutex_unlock(&mem->lock);
 		pr_debug("BO VA 0x%llx size 0x%lx is still mapped.\n",
 				mem->va, bo_size);
-		mutex_unlock(&mem->lock);
 		return -EBUSY;
 	}
 
-- 
2.26.2