Messages in this thread Patch in this message | | | Date | Wed, 12 Aug 2009 17:35:31 +0200 | From | Peter Zijlstra <> | Subject | [PATCH 2/2] perf_counter: Fix an ipi-deadlock |
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perf_pending_counter() is called from IRQ context and will call perf_counter_disable(), however perf_counter_disable() uses smp_call_function_single() which doesn't fancy being used with IRQs disabled due to IPI deadlocks.
Fix this by making it use the local __perf_counter_disable() call and teaching the counter_sched_out() code about pending disables as well.
This should cover the case where a counter migrates before the pending queue gets processed.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> --- kernel/perf_counter.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
Index: linux-2.6/kernel/perf_counter.c =================================================================== --- linux-2.6.orig/kernel/perf_counter.c +++ linux-2.6/kernel/perf_counter.c @@ -307,6 +307,10 @@ counter_sched_out(struct perf_counter *c return; counter->state = PERF_COUNTER_STATE_INACTIVE; + if (counter->pending_disable) { + counter->pending_disable = 0; + counter->state = PERF_COUNTER_STATE_OFF; + } counter->tstamp_stopped = ctx->time; counter->pmu->disable(counter); counter->oncpu = -1; @@ -2315,7 +2319,7 @@ static void perf_pending_counter(struct if (counter->pending_disable) { counter->pending_disable = 0; - perf_counter_disable(counter); + __perf_counter_disable(counter); } if (counter->pending_wakeup) { --
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