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From: Greg KH <greg@kroah.com>
To: Hans Verkuil <hverkuil@xs4all.nl>
Cc: linux-kernel@vger.kernel.org, v4l <video4linux-list@redhat.com>,
	Laurent Pinchart <laurent.pinchart@skynet.be>
Subject: Re: [BUG] cdev_put() race condition
Date: Wed, 17 Dec 2008 10:16:45 -0800	[thread overview]
Message-ID: <20081217181645.GA26161@kroah.com> (raw)
In-Reply-To: <200812171437.33695.hverkuil@xs4all.nl>

On Wed, Dec 17, 2008 at 02:37:33PM +0100, Hans Verkuil wrote:
> > Again, don't use cdev's reference counting for your own object
> > lifecycle, it is different and will cause problems, like you have found
> > out.
> 
> Sigh. It has nothing to do with how v4l uses it. And to demonstrate this, 
> here is how you reproduce it with the sg module (tested it with my USB 
> harddisk).
> 
> 1) apply this patch to char_dev.c:

<snip>

Ok, since I can't convince you that using a cdev for your reference
counting is incorrect, I'll have to go change the cdev code to prevent
you from doing this :(

Anyway, do you have a patch for the cdev code to propose how to fix this
issue you are having?

thanks,

greg k-h

  parent reply	other threads:[~2008-12-17 18:18 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-12-08 20:56 [BUG] cdev_put() race condition Hans Verkuil
2008-12-08 20:56 ` Hans Verkuil
2008-12-16 10:06 ` Hans Verkuil
2008-12-16 10:06   ` Hans Verkuil
2008-12-16 20:22 ` Greg KH
2008-12-16 21:00   ` Hans Verkuil
2008-12-16 21:00     ` Hans Verkuil
2008-12-16 21:21     ` Greg KH
2008-12-16 23:23       ` Hans Verkuil
2008-12-16 23:23         ` Hans Verkuil
2008-12-16 23:30         ` Greg KH
2008-12-17 13:37           ` Hans Verkuil
2008-12-17 13:37             ` Hans Verkuil
2008-12-17 14:52             ` Boaz Harrosh
2008-12-17 15:07               ` Hans Verkuil
2008-12-17 15:07                 ` Hans Verkuil
2008-12-17 16:09                 ` Boaz Harrosh
2008-12-17 17:33                   ` Hans Verkuil
2008-12-17 17:33                     ` Hans Verkuil
2008-12-17 18:08                     ` Al Viro
2008-12-18  8:12                       ` Boaz Harrosh
2008-12-18  8:25                     ` Boaz Harrosh
2008-12-17 18:16             ` Greg KH [this message]
2008-12-17 19:27               ` Laurent Pinchart
2008-12-17 19:27                 ` Laurent Pinchart
2008-12-17 19:35                 ` Greg KH
2008-12-17 19:30               ` Hans Verkuil
2008-12-17 19:30                 ` Hans Verkuil
2008-12-17 19:38                 ` Greg KH
2008-12-17 19:39                 ` Hans Verkuil
2008-12-17 19:39                   ` Hans Verkuil
2008-12-17 19:53                   ` Greg KH
2008-12-17 20:18                     ` Hans Verkuil
2008-12-17 20:18                       ` Hans Verkuil
2008-12-17 20:52                       ` Greg KH

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