linux-kernel - Re: [PATCH] ibmphp: Fix module ref count underflow

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Message-ID: <20081211012834.GA3262@localhost.localdomain>
Date:	Wed, 10 Dec 2008 20:28:34 -0500
From:	Neil Horman <nhorman@...driver.com>
To:	Greg KH <greg@...ah.com>
Cc:	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org
Subject: Re: [PATCH] ibmphp: Fix module ref count underflow

On Wed, Dec 10, 2008 at 02:28:12PM -0800, Greg KH wrote:
> On Wed, Dec 10, 2008 at 02:43:34PM -0500, Neil Horman wrote:
> > Hey-
> > 	I happened to notice that the ibmphp hotplug driver does something
> > rather silly in its init routine.  It purposely calls module_put so as to
> > underflow its module ref count to avoid being removed from the kernel.  This is
> > bad practice, and wrong, since it provides a window for subsequent module_gets
> > to reset the refcount to zero, allowing an unload to race in and cause all sorts
> > of mysterious panics.  If the module is unsafe to load, it should inform the
> > kernel as such with a call to __unsafe.  The patch below does that.
> > 
> > Regards
> > Neil
> > 
> > Signed-off-by: Neil Horman <nhorman@...driver.com>
> 
> Jesse is the PCI maintainer now, you should send this to him to verify
> that it goes in.
> 
> Feel free to add my:
> 	Acked-by: Greg Kroah-Hartman <gregkh@...e.de>
> 
> to this, nice job.
> 
Thanks!  I've forwarded the patch on to Jesse.

Best
Neil

> thanks,
> 
> greg k-h
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