linux-kernel - Re: [PATCH 6/9] torture: Address race in module cleanup

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Message-ID: <1410546516.12906.9.camel@linux-t7sj.site>
Date:	Fri, 12 Sep 2014 11:28:36 -0700
From:	Davidlohr Bueso <dave@...olabs.net>
To:	paulmck@...ux.vnet.ibm.com
Cc:	peterz@...radead.org, mingo@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/9] torture: Address race in module cleanup

On Fri, 2014-09-12 at 11:04 -0700, Paul E. McKenney wrote:
> On Thu, Sep 11, 2014 at 08:40:21PM -0700, Davidlohr Bueso wrote:
> > When performing module cleanups by calling torture_cleanup() the
> > 'torture_type' string in nullified However, callers are not necessarily
> > done, and might still need to reference the variable. This impacts
> > both rcutorture and locktorture, causing printing things like:
> > 
> > [   94.226618] (null)-torture: Stopping lock_torture_writer task
> > [   94.226624] (null)-torture: Stopping lock_torture_stats task
> > 
> > Thus delay this operation until the very end of the cleanup process.
> > The consequence (which shouldn't matter for this kid of program) is,
> > of course, that we delay the window between rmmod and modprobing,
> > for instance in module_torture_begin().
> > 
> > Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
> 
> Good catch!  I had just been ignoring the (null), and my scripting
> doesn't care, but it is better to have it taken care of.

In addition, for locktorture this issue can cause not only null but the
printing the wrong cleanup string when a new module is loaded with a
different torture_type.

Thanks,
Davidlohr

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