[PATCH] ARM64: smp: Silence suspicious RCU usage with ipi tracepoints

Catalin Marinas catalin.marinas at arm.com
Thu Jun 25 06:24:54 PDT 2015

On Wed, Jun 24, 2015 at 02:59:30PM -0700, Stephen Boyd wrote:
> On 06/24/2015 02:29 PM, Peter Zijlstra wrote:
> > On Wed, Jun 24, 2015 at 01:14:18PM -0700, Stephen Boyd wrote:
> >> John Stultz reported an RCU splat on ARM with ipi trace events
> >> enabled. It looks like the same problem exists on ARM64.
> >>
> >> At this point in the IPI handling path we haven't called
> >> irq_enter() yet, so RCU doesn't know that we're about to exit
> >> idle and properly warns that we're using RCU from an idle CPU.
> >> Use trace_ipi_entry_rcuidle() instead of trace_ipi_entry() so
> >> that RCU is informed about our exit from idle.
> > I have a problem with $subject. It says 'silence', whereas afaict this
> > fixes an actual bug, so it should be 'fixes'.
> Fair enough. I can resend or whoever applies this patch can
> s/Silence/Fix/ on the $subject.

I'll apply the patch and change the subject as well.



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