Re: powerpc/powernv: Fix race in updating core_idle_state

2015-07-05 Thread Shreyas B Prabhu
> > What are the symptoms of this bug? > In the cases where we hit this race and the core enters fastsleep, code mistakes an idle thread as running. Because of this, the first thread waking up from fastsleep which is supposed to resync timebase skips it. So we can end up having a core with sta

Re: powerpc/powernv: Fix race in updating core_idle_state

2015-07-05 Thread Michael Ellerman
On Wed, 2015-01-07 at 06:34:10 UTC, "Shreyas B. Prabhu" wrote: > core_idle_state is maintained for each core. It uses 0-7 bits to track > whether a thread in the core has entered fastsleep or winkle. 8th bit is > used as a lock bit. > The lock bit is set in these 2 scenarios- > - The thread is fir