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

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Message-ID: <20140912190328.GK4775@linux.vnet.ibm.com>
Date:	Fri, 12 Sep 2014 12:03:28 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Davidlohr Bueso <dave@...olabs.net>
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, Sep 12, 2014 at 11:28:36AM -0700, Davidlohr Bueso wrote:
> 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.

That would be even more annoying.  ;-)

							Thanx, Paul

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