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| author | Peter Zijlstra <peterz@infradead.org> | 2016-03-18 17:31:27 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-03-21 09:08:17 +0100 |
| commit | e8d8a90fc5014e4cdcf1de2f320081d26c7f440f (patch) | |
| tree | adefe3bc51d02011ea1c6237d91bcadc0dec43f3 /arch/x86 | |
| parent | 91a612eea9a316c464cc170ff8492ec09e7d1c69 (diff) | |
| download | blackbird-obmc-linux-e8d8a90fc5014e4cdcf1de2f320081d26c7f440f.tar.gz blackbird-obmc-linux-e8d8a90fc5014e4cdcf1de2f320081d26c7f440f.zip | |
perf/x86/BTS: Fix RCU usage
This splat reminds us:
[ 8166.045595] [ INFO: suspicious RCU usage. ]
[ 8166.168972] [<ffffffff81127837>] lockdep_rcu_suspicious+0xe7/0x120
[ 8166.175966] [<ffffffff811e0bae>] perf_callchain+0x23e/0x250
[ 8166.182280] [<ffffffff811dda3d>] perf_prepare_sample+0x27d/0x350
[ 8166.189082] [<ffffffff8100f503>] intel_pmu_drain_bts_buffer+0x133/0x200
... that as the core code does, one should hold rcu_read_lock() over that
entire BTS event-output generation sequence as well.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/events/intel/ds.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index ce7211a07c0b..8584b90d8e0b 100644 --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -570,11 +570,12 @@ int intel_pmu_drain_bts_buffer(void) * We will overwrite the from and to address before we output * the sample. */ + rcu_read_lock(); perf_prepare_sample(&header, &data, event, ®s); if (perf_output_begin(&handle, event, header.size * (top - base - skip))) - return 1; + goto unlock; for (at = base; at < top; at++) { /* Filter out any records that contain kernel addresses. */ @@ -593,6 +594,8 @@ int intel_pmu_drain_bts_buffer(void) /* There's new data available. */ event->hw.interrupts++; event->pending_kill = POLL_IN; +unlock: + rcu_read_unlock(); return 1; } |
