[PATCH 3/3] dma-buf: validate the attachment before asserting its reservation lock

[Davidlohr Bueso]

dma_buf_phys_vec_to_sgt() asserts the reservation lock before its
NULL checks run. Validate first, then assert.

Fixes: 3aa31a8bb11e ("dma-buf: provide phys_vec to scatter-gather mapping 
routine")
Signed-off-by: Davidlohr Bueso <d...@stgolabs.net>
---
 drivers/dma-buf/dma-buf-mapping.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/dma-buf-mapping.c 
b/drivers/dma-buf/dma-buf-mapping.c
index 833be519e1e6..12674d89b23e 100644
--- a/drivers/dma-buf/dma-buf-mapping.c
+++ b/drivers/dma-buf/dma-buf-mapping.c
@@ -111,12 +111,12 @@ struct sg_table *dma_buf_phys_vec_to_sgt(struct 
dma_buf_attachment *attach,
        size_t i;
        int ret;
 
-       dma_resv_assert_held(attach->dmabuf->resv);
-
        if (WARN_ON(!attach || !attach->dmabuf || !provider))
                /* This function is supposed to work on MMIO memory only */
                return ERR_PTR(-EINVAL);
 
+       dma_resv_assert_held(attach->dmabuf->resv);
+
        dma = kzalloc_obj(*dma);
        if (!dma)
                return ERR_PTR(-ENOMEM);
-- 
2.39.5