dma-buf: Make locking consistent in dma_buf_detach()

The dma_buf_detach() locks attach->dmabuf->resv and then unlocks
dmabuf->resv, which could be a two different locks from a static
code checker perspective. In particular this triggers Smatch to
report the "double unlock" error. Make the locking pointers consistent.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/dri-devel/Y1fLfsccW3AS%2Fo+%2F@kili/
Fixes: 809d9c72c2f8 ("dma-buf: Move dma_buf_attach() to dynamic locking specification")
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221030154412.8320-2-dmitry.osipenko@collabora.com

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index c40d72d..13bfd2d 100644 (file)
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -995,10 +995,10 @@ static void __unmap_dma_buf(struct dma_buf_attachment *attach,
  */
 void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
 {
-       if (WARN_ON(!dmabuf || !attach))
+       if (WARN_ON(!dmabuf || !attach || dmabuf != attach->dmabuf))
                return;
 
-       dma_resv_lock(attach->dmabuf->resv, NULL);
+       dma_resv_lock(dmabuf->resv, NULL);
 
        if (attach->sgt) {