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

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Message-ID: <20090418125111.6646e997@linux-lm>
Date:	Sat, 18 Apr 2009 12:51:11 +0800
From:	leiming <tom.leiming@...il.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Adrian Bunk <bunk@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Natalie Protasevich <protasnb@...il.com>,
	Kernel Testers List <kernel-testers@...r.kernel.org>,
	Network Development <netdev@...r.kernel.org>,
	Linux ACPI <linux-acpi@...r.kernel.org>,
	Linux PM List <linux-pm@...ts.linux-foundation.org>,
	Linux SCSI List <linux-scsi@...r.kernel.org>,
	video4linux-list@...hat.com, laurent.pinchart@...net.be,
	mchehab@...radead.org
Subject: Re: 2.6.30-rc2-git2: Reported regressions from 2.6.29

On Fri, 17 Apr 2009 19:55:29 -0700 (PDT)
Linus Torvalds <torvalds@...ux-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.

>From a3b3d72cdd57a0699fb643b41b78eb7beb211ff5 Mon Sep 17 00:00:00 2001
From: Ming Lei <tom.leiming@...il.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@...il.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





-- 
Lei Ming
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