On Thursday, September 08, 2016 11:28:48 AM Srinivas Pandruvada wrote: > On Thu, 2016-09-08 at 20:22 +0200, Peter Zijlstra wrote: > > On Thu, Sep 08, 2016 at 11:09:28AM -0700, Tim Chen wrote: > > > > > > On Thu, Sep 08, 2016 at 09:59:55AM +0200, Peter Zijlstra wrote: > > > > > > > > I think there's a race here, if two tasks were to write to the > > > > sysctl > > > > they'd both change the value before getting stuck on the mutex in > > > > enable_sched_itmt(). > > > > > > > > One way around that is doing something like: > > > > > > > > > > > > struct ctl_table t; > > > > int val = sysctl_sched_itmt_enabled; > > > > > > > > t = *table; > > > > t.data = &val; > > > > > > > > proc_dointvec_minmax(&t, ...); > > > > > > > > /* and update the sysctl_sched_itmt_enabled value inside the > > > > mutex */ > > > > enable_sched_itmi(val); > > > > > > Peter, > > > > > > Since enable_sched_itmt is only used by sched_itmt_update_handler, > > > I've moved the mutex locking to sched_itmt_update_handler to > > > eliminate > > > the race condition in the code path you mentioned. > > > > That is indeed simpler. Thanks! > Do we need to send v3 to include these changes? Yes, please. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
