2014-01-07 13:56:00

by Ricardo Ribalda Delgado

Subject: [PATCH] vb2: Check if there are buffers before streamon

This patch adds a test preventing streamon() if there is no buffer
ready.

Without this patch, a user could call streamon() before
preparing any buffer. This leads to a situation where if he calls
close() before calling streamoff() the device is kept streaming.

Signed-off-by: Ricardo Ribalda Delgado <[email protected]>
---
drivers/media/v4l2-core/videobuf2-core.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 098df28..6f20e5a 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1776,6 +1776,11 @@ static int vb2_internal_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
return 0;
}

+ if (!q->num_buffers) {
+ dprintk(1, "streamon: no frames have been requested\n");
+ return -EINVAL;
+ }
+
/*
* If any buffers were queued before streamon,
* we can now pass them to driver for processing.
--
1.8.5.2

2014-01-07 15:38:34

by Marek Szyprowski

Subject: Re: [PATCH] vb2: Check if there are buffers before streamon

Hi,

On 2014-01-07 14:55, Ricardo Ribalda Delgado wrote:
> This patch adds a test preventing streamon() if there is no buffer
> ready.
>
> Without this patch, a user could call streamon() before
> preparing any buffer. This leads to a situation where if he calls
> close() before calling streamoff() the device is kept streaming.
>
> Signed-off-by: Ricardo Ribalda Delgado <[email protected]>
> ---
> drivers/media/v4l2-core/videobuf2-core.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index 098df28..6f20e5a 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -1776,6 +1776,11 @@ static int vb2_internal_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
> return 0;
> }
>
> + if (!q->num_buffers) {
> + dprintk(1, "streamon: no frames have been requested\n");

I think that "streamon: error - no buffers have been allocated\n"
message is a bit
more descriptive and it matches the definitions used elsewhere in the
debug messages.
Please don't mix buffers and frames.

> + return -EINVAL;
> + }
> +
> /*
> * If any buffers were queued before streamon,
> * we can now pass them to driver for processing.

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland