[PATCH v1 1/2] dma-buf: Make locking consistent in dma_buf_detach()

[Dmitry Osipenko]

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 at oracle.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 at collabora.com>
---
 drivers/dma-buf/dma-buf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index c40d72d318fd..6e33ef4fde34 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -998,9 +998,10 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
 	if (WARN_ON(!dmabuf || !attach))
 		return;
 
-	dma_resv_lock(attach->dmabuf->resv, NULL);
+	dma_resv_lock(dmabuf->resv, NULL);
 
 	if (attach->sgt) {
+		WARN_ON(dmabuf != attach->dmabuf);
 
 		__unmap_dma_buf(attach, attach->sgt, attach->dir);
 
-- 
2.37.3