Hi all,
I'm extending v4l2-compliance with support for VIDIOC_REQBUFS and
VIDIOC_CREATE_BUFS,
and I ran into an undefined issue: what happens if VIDIOC_CREATE_BUFS is called
with
count set to 0?
I think there should be a separate test for that. Right now queue_setup will
receive
a request for 0 buffers, and I don't know if drivers expect a zero value there.
I suggest that CREATE_BUFS with a count of 0 will only check whether memory and
format.type are valid, and if they are it will just return 0 and do nothing.
Also note that this code in vb2_create_bufs is wrong:
ret = __vb2_queue_alloc(q, create->memory, num_buffers,
num_planes);
if (ret < 0) {
dprintk(1, "Memory allocation failed with error: %d\n", ret);
return ret;
}
It should be:
if (ret == 0) {
__vb2_queue_alloc() returns the number of buffers it managed to allocate,
which is never < 0.
I propose to add the patch included below.
Comments are welcome!
Regards,
Hans
diff --git a/drivers/media/video/videobuf2-core.c
b/drivers/media/video/videobuf2-core.c
index a0702fd..01a8312 100644
--- a/drivers/media/video/videobuf2-core.c
+++ b/drivers/media/video/videobuf2-core.c
@@ -647,6 +647,9 @@ int vb2_create_bufs(struct vb2_queue *q, struct
v4l2_create_buffers *create)
return -EINVAL;
}
+ if (create->count == 0)
+ return 0;
+
if (q->num_buffers == VIDEO_MAX_FRAME) {
dprintk(1, "%s(): maximum number of buffers already
allocated\n",
__func__);
@@ -675,7 +678,7 @@ int vb2_create_bufs(struct vb2_queue *q, struct
v4l2_create_buffers *create)
/* Finally, allocate buffers and video memory */
ret = __vb2_queue_alloc(q, create->memory, num_buffers,
num_planes);
- if (ret < 0) {
+ if (ret == 0) {
dprintk(1, "Memory allocation failed with error: %d\n", ret);
return ret;
}
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