Messages in this thread | | | Date | Sun, 18 Aug 2013 20:55:28 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH tip/core/rcu 1/5] rcu: Add duplicate-callback tests to rcutorture |
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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" <paulmck@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 <paulmck@linux.vnet.ibm.com> > > Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> > > Cc: Sedat Dilek <sedat.dilek@gmail.com> > > Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> > > Cc: Rik van Riel <riel@surriel.com> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: Linus Torvalds <torvalds@linux-foundation.org> > > Tested-by: Sedat Dilek <sedat.dilek@gmail.com> > > Two comments below; with those fixed, > Reviewed-by: Josh Triplett <josh@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?
> > @@ -2163,6 +2178,28 @@ rcu_torture_init(void) > > firsterr = retval; > > goto unwind; > > } > > + if (object_debug) { > > +#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD > > + struct rcu_head rh1; > > + struct rcu_head rh2; > > + > > + init_rcu_head_on_stack(&rh1); > > + init_rcu_head_on_stack(&rh2); > > + pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n"); > > + local_irq_disable(); /* Make it hard to finish grace period. */ > > + call_rcu(&rh1, rcu_torture_leak_cb); /* start grace period. */ > > + call_rcu(&rh2, rcu_torture_err_cb); > > + call_rcu(&rh2, rcu_torture_err_cb); /* duplicate callback. */ > > + local_irq_enable(); > > + rcu_barrier(); > > + pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n"); > > + destroy_rcu_head_on_stack(&rh1); > > + destroy_rcu_head_on_stack(&rh2); > > +#else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ > > + pr_alert("rcutorture: !%s, not testing duplicate call_rcu()\n", > > + "CONFIG_DEBUG_OBJECTS_RCU_HEAD"); > > Why put this parameter in a separate string? That makes it harder to > grep for the full error message. (That's assuming you keep the error > message, given the comment above.)
Force of habit, fixed. ;-)
Thanx, Paul
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