linux-kernel - Re: [linux-usb-devel] Bug creating USB endpoints in 2.6.20.x (kernel bug 8198)

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Message-ID: <4641CD01.6010309@gmail.com>
Date:	Wed, 09 May 2007 15:30:41 +0200
From:	Tejun Heo <htejun@...il.com>
To:	Chris Rankin <rankincj@...oo.com>
CC:	Alan Stern <stern@...land.harvard.edu>,
	linux-usb-devel@...ts.sourceforge.net,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Greg K-H <greg@...ah.com>
Subject: Re: [linux-usb-devel] Bug creating USB endpoints in 2.6.20.x (kernel
 bug 8198)

Chris Rankin wrote:
> --- Tejun Heo <htejun@...il.com> wrote:
>> So, we can fix the problem Chris is seeing by breaking module unload (by
>> allowing it to unload too early).  It doesn't sound too hot but module
>> unloading race is much less likely than sysfs node deletion/open race.
> 
> Yikes! Just temporary breakage, I hope :-)!! The only modules I unload on a regular basis these
> days are things like "microcode", which the init scripts take care of as part of the boot-up
> process.

Okay, here's a half-assed fix.  With this patch applied, if you try to
unload a module while you're opening it's dev attribute, kernel will
oops later when the file is accessed or closed later but it should fix
the bug winecfg triggers.  I really dunno how to fix this the right way
in the stable kernel.  Better ideas?  Anyone?

-- 
tejun

View attachment "sysfs-race-fix.patch" of type "text/x-patch" (2414 bytes)