diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-04-08 15:01:25 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-04-08 18:53:27 +0200 |
| commit | e30e08f65c7ef6c230424264f09c3d53f117f58b (patch) | |
| tree | bc30c6a31dc53932a5f7030402e87b36d7bddc07 /kernel | |
| parent | 7333a8003cdc0470e8c0ae8b949cbc44f3165ff3 (diff) | |
perf_counter: fix NMI race in task clock
We should not be updating ctx->time from NMI context, work around that.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130408.681326666@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/perf_counter.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 863703b3158..84a39081344 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -319,8 +319,6 @@ static void __perf_counter_disable(void *info) spin_lock_irqsave(&ctx->lock, flags); - update_context_time(ctx); - /* * If the counter is on, turn it off. * If it is in error state, leave it in error state. @@ -2335,13 +2333,11 @@ static const struct hw_perf_counter_ops perf_ops_cpu_clock = { * Software counter: task time clock */ -static void task_clock_perf_counter_update(struct perf_counter *counter) +static void task_clock_perf_counter_update(struct perf_counter *counter, u64 now) { - u64 prev, now; + u64 prev; s64 delta; - now = counter->ctx->time; - prev = atomic64_xchg(&counter->hw.prev_count, now); delta = now - prev; atomic64_add(delta, &counter->count); @@ -2369,13 +2365,24 @@ static int task_clock_perf_counter_enable(struct perf_counter *counter) static void task_clock_perf_counter_disable(struct perf_counter *counter) { hrtimer_cancel(&counter->hw.hrtimer); - task_clock_perf_counter_update(counter); + task_clock_perf_counter_update(counter, counter->ctx->time); + } static void task_clock_perf_counter_read(struct perf_counter *counter) { - update_context_time(counter->ctx); - task_clock_perf_counter_update(counter); + u64 time; + + if (!in_nmi()) { + update_context_time(counter->ctx); + time = counter->ctx->time; + } else { + u64 now = perf_clock(); + u64 delta = now - counter->ctx->timestamp; + time = counter->ctx->time + delta; + } + + task_clock_perf_counter_update(counter, time); } static const struct hw_perf_counter_ops perf_ops_task_clock = { |