On Tue, Jan 29, 2019 at 7:16 AM Peter Zijlstra <[email protected]> wrote: > > On Tue, Jan 29, 2019 at 01:38:43PM +0100, Peter Zijlstra wrote: > > On Thu, Jan 24, 2019 at 01:15:18PM -0800, Suren Baghdasaryan wrote: > > > + atomic_set(&group->polling, polling); > > > + /* > > > + * Memory barrier is needed to order group->polling > > > + * write before times[] read in collect_percpu_times() > > > + */ > > > + smp_mb__after_atomic(); > > > > That's broken, smp_mb__{before,after}_atomic() can only be used on > > atomic RmW operations, something atomic_set() is _not_. > > Also; the comment should explain _why_ not only what.
Got it. Will change the comment to something like: Order group->polling=0 before reading times[] in collect_percpu_times() to detect possible race with hotpath that modifies times[] before it sets group->polling=1 (see Race #1 in the comments at the top). > -- > You received this message because you are subscribed to the Google Groups > "kernel-team" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. >
