linux-kernel - [PATCH] v4l: saa7134: fix race between opening and closing the device

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Message-ID: <20080609190854.GA5855@joi>
Date:	Mon, 9 Jun 2008 21:08:57 +0200
From:	Marcin Slusarz <marcin.slusarz@...il.com>
To:	video4linux-list@...hat.com, LKML <linux-kernel@...r.kernel.org>
Cc:	Mauro Carvalho Chehab <mchehab@...radead.org>
Subject: [PATCH] v4l: saa7134: fix race between opening and closing the
	device

On Sun, Jun 08, 2008 at 08:31:04AM +0200, Marcin Slusarz wrote:
> On Sun, Jun 08, 2008 at 12:48:35AM +0200, Marcin Slusarz wrote:
> > (...)
> 
> This patch is stupid. Please ignore.

Ok, I think this one should be considered for inclusion.
I don't think it has anything to do with oops in empress_querycap,
but who knows ;)
Compile tested only.
---
From: Marcin Slusarz <marcin.slusarz@...il.com>
Subject: [PATCH] v4l: saa7134: fix race between opening and closing the device

decrementing dev->empress_users should be done as last action of ts_release,
because it sleeps and write access to dev->empress_started is not protected
in any way
(additionally closing thread could mute audio after opening thread unmuted it)

Signed-off-by: Marcin Slusarz <marcin.slusarz@...il.com>
Cc: Mauro Carvalho Chehab <mchehab@...radead.org>
Cc: video4linux-list@...hat.com
---
 drivers/media/video/saa7134/saa7134-empress.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/media/video/saa7134/saa7134-empress.c b/drivers/media/video/saa7134/saa7134-empress.c
index 81431ee..0da683a 100644
--- a/drivers/media/video/saa7134/saa7134-empress.c
+++ b/drivers/media/video/saa7134/saa7134-empress.c
@@ -112,7 +112,6 @@ static int ts_release(struct inode *inode, struct file *file)
 
 	videobuf_stop(&dev->empress_tsq);
 	videobuf_mmap_free(&dev->empress_tsq);
-	dev->empress_users--;
 
 	/* stop the encoder */
 	ts_reset_encoder(dev);
@@ -121,6 +120,8 @@ static int ts_release(struct inode *inode, struct file *file)
 	saa_writeb(SAA7134_AUDIO_MUTE_CTRL,
 		saa_readb(SAA7134_AUDIO_MUTE_CTRL) | (1 << 6));
 
+	dev->empress_users--;
+
 	return 0;
 }
 
-- 
1.5.4.5

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