Re: [PATCH tip/core/rcu 2/3] rcutorture: Test both RCU-sched and RCU-bh for Tiny RCU

[Josh Triplett <josh@joshtriplett.org>]

On Wed, May 13, 2015 at 06:07:28AM -0700, Paul E. McKenney wrote:
> On Tue, May 12, 2015 at 05:59:29PM -0700, josh@joshtriplett.org wrote:
> > On Tue, May 12, 2015 at 03:49:12PM -0700, Paul E. McKenney wrote:
> > > From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> > > 
> > > Reported-by: "Ahmed, Iftekhar" <ahmedi@onid.oregonstate.edu>
> > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> > 
> > Could you elaborate a bit more on this patch (ideally in its commit
> > message)?  I see an addition of a command-line parameter to test rcu_bh;
> > is rcu-sched already tested elsewhere by some other config, or does this
> > parameter somehow enable testing both?
> 
> The commit log now reads as follows, does that help?
> 
> 							Thanx, Paul
> 
> ------------------------------------------------------------------------
> 
> rcutorture: Test both RCU-sched and RCU-bh for Tiny RCU
> 
> Tiny RCU supports both RCU-sched and RCU-bh, but only RCU-sched is
> currently tested by the rcutorture scripts.  This commit therefore
> changes the TINY02 configuration to test RCU-bh, with TINY01 continuing
> to test RCU-sched.
> 
> This shortcoming of the current rcutorture tests was located by mutation
> testing by Iftekhar.  The idea behind mutation testing is to automatically
> mutate the code under test.  If a given mutant is not caught by testing,
> this is a hint that the testing might need to be improved, as was the
> case here.  Note that this is only a hint because it is possible to mutate
> the code into something else that still works.  For example, a mutation
> that removes (say) a WARN_ON() will not normally result in a test failure.
> 
> This change resulted in the test failure caused by list mishandling,
> which is fixed by the next commit.
> 
> Reported-by: "Ahmed, Iftekhar" <ahmedi@onid.oregonstate.edu>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> 
Much better, thanks.  In particular, the information about TINY01 and
TINY02 was not obvious from the patch.
Reviewed-by: Josh Triplett <josh@joshtriplett.org>