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V4L/DVB (7494): videobuf-dma-sg.c: Avoid NULL dereference and add comment about backwards compatibility

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Signed-off-by: Brandon Philips <bphilips@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This commit is contained in:
Brandon Philips 2008-04-02 18:10:59 -03:00 • committed by Mauro Carvalho Chehab
commit ce54093cef
1 changed files with 15 additions and 1 deletions
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16
drivers/media/video/videobuf-dma-sg.c
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@ -546,6 +546,14 @@ static int __videobuf_mmap_mapper(struct videobuf_queue *q,
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 @@ static int __videobuf_mmap_mapper(struct videobuf_queue *q,
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;