On Sun, Aug 18, 2013 at 08:55:28PM -0700, Paul E. McKenney wrote: > On Sat, Aug 17, 2013 at 07:54:20PM -0700, Josh Triplett wrote: > > On Sat, Aug 17, 2013 at 07:25:13PM -0700, Paul E. McKenney wrote: > > > From: "Paul E. McKenney" <paul...@linux.vnet.ibm.com> > > > > > > This commit adds a object_debug option to rcutorture to allow the > > > debug-object-based checks for duplicate call_rcu() invocations to > > > be deterministically tested. > > > > > > Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com> > > > Cc: Mathieu Desnoyers <mathieu.desnoy...@efficios.com> > > > Cc: Sedat Dilek <sedat.di...@gmail.com> > > > Cc: Davidlohr Bueso <davidlohr.bu...@hp.com> > > > Cc: Rik van Riel <r...@surriel.com> > > > Cc: Thomas Gleixner <t...@linutronix.de> > > > Cc: Linus Torvalds <torva...@linux-foundation.org> > > > Tested-by: Sedat Dilek <sedat.di...@gmail.com> > > > > Two comments below; with those fixed, > > Reviewed-by: Josh Triplett <j...@joshtriplett.org> > > > > > --- > > > @@ -100,6 +101,8 @@ module_param(fqs_stutter, int, 0444); > > > MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)"); > > > module_param(n_barrier_cbs, int, 0444); > > > MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier > > > testing"); > > > +module_param(object_debug, int, 0444); > > > +MODULE_PARM_DESC(object_debug, "Enable debug-object double call_rcu() > > > testing"); > > > > modules-next has a change to ignore and warn about > > unknown module parameters. Thus, I'd suggest wrapping the ifdef around > > this module parameter, so it doesn't exist at all without > > CONFIG_DEBUG_OBJECTS_RCU_HEAD. > > > > Alternatively, consider providing the test unconditionally, and just > > printing a big warning message saying that it's going to cause > > corruption in the !CONFIG_DEBUG_OBJECTS_RCU_HEAD case. > > I currently do something like the above. The module parameter > is defined unconditionally, but the actual tests are under #ifdef > CONFIG_DEBUG_OBJECTS_RCU_HEAD. If you specify object_debug for a > !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel, the pr_alert() below happens, > and the test is omitted, thus avoiding the list corruption. > > Seem reasonable?
That's exactly the bit I was commenting on. I'm saying that you should either make the test unconditional (perhaps with a warning saying it's about to cause list corruption), or you should compile out the module parameter as well and then you don't need the pr_alert (since current kernels will emit a warning when you pass a non-existent module parameter). Personally, I'd go with the latter. - Josh Triplett -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
