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