V4L/DVB (7494): videobuf-dma-sg.c: Avoid NULL dereference and add comment about backwards compatibility
Signed-off-by: Brandon Philips <bphilips@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/videobuf-dma-sg.c b/drivers/media/video/videobuf-dma-sg.c
index 717783f..e6ce99f 100644
--- a/drivers/media/video/videobuf-dma-sg.c
+++ b/drivers/media/video/videobuf-dma-sg.c
@@ -546,6 +546,14 @@
goto done;
}
+ /* This function maintains backwards compatibility with V4L1 and will
+ * map more than one buffer if the vma length is equal to the combined
+ * size of multiple buffers than it will map them together. See
+ * VIDIOCGMBUF in the v4l spec
+ *
+ * TODO: Allow drivers to specify if they support this mode
+ */
+
/* look for first buffer to map */
for (first = 0; first < VIDEO_MAX_FRAME; first++) {
if (NULL == q->bufs[first])
@@ -590,10 +598,16 @@
map = kmalloc(sizeof(struct videobuf_mapping),GFP_KERNEL);
if (NULL == map)
goto done;
- for (size = 0, i = first; i <= last; size += q->bufs[i++]->bsize) {
+
+ size = 0;
+ for (i = first; i <= last; i++) {
+ if (NULL == q->bufs[i])
+ continue;
q->bufs[i]->map = map;
q->bufs[i]->baddr = vma->vm_start + size;
+ size += q->bufs[i]->bsize;
}
+
map->count = 1;
map->start = vma->vm_start;
map->end = vma->vm_end;