[PATCH] ARM: perf: do not handle deleted counter in irq handler to avoid oops

[Will Deacon]

On Tue, Feb 21, 2012 at 03:34:58PM +0000, Ming Lei wrote:
> On Tue, Feb 21, 2012 at 11:19 PM, Will Deacon <will.deacon at arm.com> wrote:
> > On Tue, Feb 21, 2012 at 02:02:32PM +0000, Ming Lei wrote:
> >> On Tue, Feb 21, 2012 at 9:32 PM, Will Deacon <will.deacon at arm.com> wrote:
> >> > I have a couple of patches that solve this by (a) clearing the overflow flag
> >> > when disabling the counter for ARMv7 and (b) adding the event checks to the
> >>
> >> Maybe ARMv6 and xscale need to be fixed too if the overflow flag will be kept
> >> even after the counter is disabled.
> >
> > I don't think so - seems like we clear the overflow flag already for those
> > PMUs in the disable path (note that we write ~mask).
> 
> mask is only the counters enable bits, both v6 and xscale don't clear their
> overflow flag in disable callback.

Sure they do. When we read-modify-write the pmcr we &= ~mask, so we end up
writing the overflow flags back if they are set, which is sufficient to
clear them.

Will