Messages in this thread | | | Date | Thu, 13 Aug 2009 10:29:01 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 4/2] perf_counter: Fix swcounter context invariance |
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On Thu, Aug 13, 2009 at 10:22:58AM +0200, Peter Zijlstra wrote: > On Thu, 2009-08-13 at 10:05 +0200, Frederic Weisbecker wrote: > > On Thu, Aug 13, 2009 at 09:51:55AM +0200, Peter Zijlstra wrote: > > > Not really related to this topic, but it needs posting anyway. > > > > > > --- > > > > > > Subject: perf_counter: Fix swcounter context invariance > > > From: Peter Zijlstra <a.p.zijlstra@chello.nl> > > > Date: Fri Aug 07 13:29:13 CEST 2009 > > > > > > perf_swcounter_is_counting() uses a lock, which means we cannot use > > > swcounters from NMI or when holding that particular lock, this is > > > unintended. > > > > > > The below removes the lock, this opens up race window, but not worse > > > than the swcounters already experience due to RCU traversal of the > > > context in perf_swcounter_ctx_event(). > > > > > > Cc: Paul Mackerras <paulus@samba.org> > > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> > > > > > > > > As a side effect, it's possible this also fixes the hard lockups > > while opening a lockdep tracepoint counter. > > It will -- not a side-effect at all, intended consequence :-)
Great then! Important fix for .31 :-)
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