Re: 2.6.30-rc2-git2: Reported regressions from 2.6.29

Rafael J. Wysocki
2009-04-18T12:33:09Z

On Saturday 18 April 2009, leiming wrote:
> On Fri, 17 Apr 2009 19:55:29 -0700 (PDT)
> Linus Torvalds <torvalds@linux-foundation.org> wrote:
>
> > > @@ -742,7 +742,7 @@ static int uvc_alloc_urb_buffers(struct
> > > uvc_video_device *video,
> > > /* Buffers are already allocated, bail out. */
> > > if (video->urb_size)
> > > - return 0;
> > > + return DIV_ROUND_UP(video->urb_size, psize);
> >
> > I don't think this is right. It should round _down_.
> >
> > It's supposed to return 'npackets', but if you pass it a different
> > packet size than it was passed originally, it can now return a
> > potentially bigger number than the already allocated buffer, no?
> >
> > So I think it should round down (ie use a regular divide). No?
>
> Yes,you are correct, please ignore my last reply, and following is
> the fixed patch.
>
> Thanks.

Thanks for the patch, I've updated the bug entry to point to it.

Best,
Rafael

> From a3b3d72cdd57a0699fb643b41b78eb7beb211ff5 Mon Sep 17 00:00:00 2001
> From: Ming Lei <tom.leiming@gmail.com>
> Date: Wed, 15 Apr 2009 22:32:51 +0800
> Subject: [PATCH] V4L/DVB:usbvideo:fix uvc resume failed(v2)
>
> Now urb buffers is not freed before suspend, so uvc_alloc_urb_buffers
> should return packet counts allocated originally during uvc resume
> , instead of zero.
>
> This version uses round down to return packet counts on Linus's
> suggestions, or else may lead to buffer destructed if packet size
> is changed before calling uvc_alloc_urb_buffers() in this kind of
> case.
>
> This patch is against v2.6.30-rc2.
>
> Signed-off-by: Ming Lei <tom.leiming@gmail.com>
> ---
> drivers/media/video/uvc/uvc_video.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/media/video/uvc/uvc_video.c b/drivers/media/video/uvc/uvc_video.c
> index a95e173..6ce974d 100644
> --- a/drivers/media/video/uvc/uvc_video.c
> +++ b/drivers/media/video/uvc/uvc_video.c
> @@ -742,7 +742,7 @@ static int uvc_alloc_urb_buffers(struct uvc_video_device *video,
>
> /* Buffers are already allocated, bail out. */
> if (video->urb_size)
> - return 0;
> + return video->urb_size / psize;
>
> /* Compute the number of packets. Bulk endpoints might transfer UVC
> * payloads accross multiple URBs.
> --
> 1.6.0.GIT