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!
