media: videobuf2: Assert held reservation lock for dma-buf mmapping

When userspace mmaps dma-buf's fd, the dma-buf reservation lock must be
held. Add locking sanity checks to the dma-buf mmaping callbacks to ensure
that the locking assumptions won't regress in the future.
Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Acked-by: Tomasz Figa <tfiga@chromium.org>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221110201349.351294-6-dmitry.osipenko@collabora.com

drivers/media/common/videobuf2/videobuf2-dma-contig.c

@@ -11,6 +11,7 @@
  */
 
 #include <linux/dma-buf.h>
+#include <linux/dma-resv.h>
 #include <linux/module.h>
 #include <linux/refcount.h>
 #include <linux/scatterlist.h>
@@ -455,6 +456,8 @@ static int vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf, struct iosys_map *map)
 static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
 	struct vm_area_struct *vma)
 {
+	dma_resv_assert_held(dbuf->resv);
+
 	return vb2_dc_mmap(dbuf->priv, vma);
 }
 

drivers/media/common/videobuf2/videobuf2-dma-sg.c

@@ -10,6 +10,7 @@
  * the Free Software Foundation.
  */
 
+#include <linux/dma-resv.h>
 #include <linux/module.h>
 #include <linux/mm.h>
 #include <linux/refcount.h>
@@ -495,6 +496,8 @@ static int vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf,
 static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
 	struct vm_area_struct *vma)
 {
+	dma_resv_assert_held(dbuf->resv);
+
 	return vb2_dma_sg_mmap(dbuf->priv, vma);
 }
 

drivers/media/common/videobuf2/videobuf2-vmalloc.c

@@ -10,6 +10,7 @@
  * the Free Software Foundation.
  */
 
+#include <linux/dma-resv.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/mm.h>
@@ -316,6 +317,8 @@ static int vb2_vmalloc_dmabuf_ops_vmap(struct dma_buf *dbuf,
 static int vb2_vmalloc_dmabuf_ops_mmap(struct dma_buf *dbuf,
 	struct vm_area_struct *vma)
 {
+	dma_resv_assert_held(dbuf->resv);
+
 	return vb2_vmalloc_mmap(dbuf->priv, vma);
 }