linux-kernel - Re: [PATCH] drivers-core: nullify private pointer on device-release

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Message-ID: <Pine.LNX.4.64.0910051011280.4337@axis700.grange>
Date:	Mon, 5 Oct 2009 10:11:50 +0200 (CEST)
From:	Guennadi Liakhovetski <g.liakhovetski@....de>
To:	Greg KH <greg@...ah.com>
cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers-core: nullify private pointer on device-release

On Thu, 1 Oct 2009, Greg KH wrote:

> On Thu, Oct 01, 2009 at 03:45:56PM +0200, Guennadi Liakhovetski wrote:
> > On Thu, 1 Oct 2009, Greg KH wrote:
> > 
> > > On Thu, Oct 01, 2009 at 10:02:08AM +0200, Guennadi Liakhovetski wrote:
> > > > Device structures can be reused over multiple device_add / device_release 
> > > > cycles.
> > > 
> > > They shouldn't be as they should be dynamic, not static.
> > 
> > Should they? I'm pretty sure this is not the first time this comes up - 
> > there are several drivers and / or subsystems, that re-use driver objects. 
> 
> Then those drivers and subsystems should be fixed, as that is incorrect.
> 
> > But finding in mail archives wouldn't be very easy. And it worked until 
> > now - why should we break it?
> 
> I would argue that this code was always broken.
> When did this problem show up for you?

Since commit b4028437876866aba4747a655ede00f892089e14

> > > What device is having this problem?
> > 
> > My problem case is the soc-camera framework. There device struct is 
> > embedded into the video client object, which are kept as long as the 
> > driver is loaded.
> 
> struct device is a dynamic structure, it is supposed to be able to be
> freed when the last reference goes away.  Static struct device usage is
> wrong.  It sounds like the video client object code is incorrect, please
> fix it.

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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