Commit 1054598c authored Aug 06, 2009 by Peter Zijlstra Committed by Ingo Molnar Aug 06, 2009

perf_counter: Fix double list iteration in per task precise stats



Brice Goglin reported this crash with per task precise stats:

> I finally managed to test the threaded perfcounter statistics (thanks a
> lot for implementing it). I am running 2.6.31-rc5 (with the AMD
> magny-cours patches but I don't think they matter here). I am trying to
> measure local/remote memory accesses per thread during the well-known
> stream benchmark. It's compiled with OpenMP using 16 threads on a
> quad-socket quad-core barcelona machine.
>
> Command line is:
>  /mnt/scratch/bgoglin/cpunode/linux-2.6.31/tools/perf/perf record -f -s
> -e r1000001e0 -e r1000002e0 -e r1000004e0 -e r1000008e0 ./stream
>
> It seems to work fine with a single -e <counter> on the command line
> while it crashes when there are at least 2 of them.
> It seems to work fine without -s as well.

A silly copy-paste resulted in a messed up iteration which would
cause the OOPS.

Reported-by: Brice Goglin <Brice.Goglin@inria.fr>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Brice Goglin <Brice.Goglin@inria.fr>
LKML-Reference: <1249574786.32113.550.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 9424edc2

kernel/perf_counter.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1104,7 +1104,7 @@ static void perf_counter_sync_stat(struct perf_counter_context *ctx,
		__perf_counter_sync_stat(counter, next_counter);

		counter = list_next_entry(counter, event_entry);
		next_counter = list_next_entry(counter, event_entry);
		next_counter = list_next_entry(next_counter, event_entry);
		}
		}

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