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SubjectRe: [PATCH 1/4] media: pxa_camera: fix the buffer free path (fwd)
Hi Robert,

No idea why this mail hasn't been delivered... Sorry, resending.

Thanks
Guennadi

---------- Forwarded message ----------
Date: Sun, 31 May 2015 21:34:50 +0200 (CEST)
From: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Subject: Re: [PATCH 1/4] media: pxa_camera: fix the buffer free path

Hi Robert,

Thanks for the patch.

On Sun, 22 Mar 2015, Robert Jarzmik wrote:

> From: Robert Jarzmik <robert.jarzmik@intel.com>

free_buffer() is called from two locations: from the .buf_release()
callback and on the error path in .buf_prepare(). In the first case it
does the complete freeing of the buffers and DMA channels, in the latter
case the error path, including buffer freeing can _only_ be entered if
buffer allocation has been attempted, i.e. buffer state is
VIDEOBUF_NEEDS_INIT. Which is exactly the case you're catching below.
Following your patch, in this case free_buffer() shouldn't be called at
all, because videobuf_waiton() isn't needed either. That can be achieved
easier:

fail_u:
dma_free_coherent(dev, buf->dmas[0].sg_size,
buf->dmas[0].sg_cpu, buf->dmas[0].sg_dma);
-fail:
- free_buffer(vq, buf);
out:
buf->inwork = 0;
return ret;

But tbh I don't understand why videobuf_dma_free() and
videobuf_dma_unmap() shouldn't be called if videobuf_iolock() was
successful, are you sure about that?

Thanks
Guennadi

> Fix the error path where the video buffer wasn't allocated nor
> mapped. In this case, in the driver free path don't try to unmap memory
> which was not mapped in the first place.
>
> Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
> ---
> drivers/media/platform/soc_camera/pxa_camera.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/platform/soc_camera/pxa_camera.c b/drivers/media/platform/soc_camera/pxa_camera.c
> index 8d6e343..3ca33f0 100644
> --- a/drivers/media/platform/soc_camera/pxa_camera.c
> +++ b/drivers/media/platform/soc_camera/pxa_camera.c
> @@ -272,8 +272,8 @@ static void free_buffer(struct videobuf_queue *vq, struct pxa_buffer *buf)
> * longer in STATE_QUEUED or STATE_ACTIVE
> */
> videobuf_waiton(vq, &buf->vb, 0, 0);
> - videobuf_dma_unmap(vq->dev, dma);
> - videobuf_dma_free(dma);
> + if (buf->vb.state == VIDEOBUF_NEEDS_INIT)
> + return;
>
> for (i = 0; i < ARRAY_SIZE(buf->dmas); i++) {
> if (buf->dmas[i].sg_cpu)
> @@ -283,6 +283,8 @@ static void free_buffer(struct videobuf_queue *vq, struct pxa_buffer *buf)
> buf->dmas[i].sg_dma);
> buf->dmas[i].sg_cpu = NULL;
> }
> + videobuf_dma_unmap(vq->dev, dma);
> + videobuf_dma_free(dma);
>
> buf->vb.state = VIDEOBUF_NEEDS_INIT;
> }
> --
> 2.1.4
>


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