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

From	Steven Rostedt <rostedt@goodmis.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] ARM64: smp: Silence suspicious RCU usage with ipi tracepoints
Date	2015-06-25 03:10 +0200
Message-ID	<pF3PX-1xZ-7@gated-at.bofh.it> (permalink)
References	<pEZjj-3sv-7@gated-at.bofh.it> <pF0p4-4YX-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, 24 Jun 2015 23:29:30 +0200
Peter Zijlstra <peterz@infradead.org> 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'.

Agreed, otherwise Acked-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve
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Re: [PATCH] ARM64: smp: Silence suspicious RCU usage with ipi  tracepoints Peter Zijlstra <peterz@infradead.org> - 2015-06-24 23:30 +0200
  Re: [PATCH] ARM64: smp: Silence suspicious RCU usage with ipi tracepoints Stephen Boyd <sboyd@codeaurora.org> - 2015-06-25 00:10 +0200
  Re: [PATCH] ARM64: smp: Silence suspicious RCU usage with ipi  tracepoints Steven Rostedt <rostedt@goodmis.org> - 2015-06-25 03:10 +0200

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