diff options
| author | Will Deacon <will.deacon@arm.com> | 2011-07-01 14:38:12 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-08-03 12:42:27 -0700 |
| commit | d00726a966330f798b9cb055611be5d11547dbdd (patch) | |
| tree | bbefc68b1ff1114c114e7c5a16b29457b2248e6d | |
| parent | f26417930bc1b60ffd1a0ffc11e4a86a48e9d9bc (diff) | |
ARM: 6989/1: perf: do not start the PMU when no events are present
commit f4f38430c94c38187db73a2cf3892cc8b12a2713 upstream.
armpmu_enable can be called in situations where no events are present
(for example, from the event rotation tick after a profiled task has
exited). In this case, we currently start the PMU anyway which may
leave it active inevitably without any events being monitored.
This patch adds a simple check to the enabling code so that we avoid
starting the PMU when no events are present.
Reported-by: Ashwin Chaugle <ashwinc@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | arch/arm/kernel/perf_event.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c index 139e3c82736..d284a30b98e 100644 --- a/arch/arm/kernel/perf_event.c +++ b/arch/arm/kernel/perf_event.c @@ -588,7 +588,7 @@ static int armpmu_event_init(struct perf_event *event) static void armpmu_enable(struct pmu *pmu) { /* Enable all of the perf events on hardware. */ - int idx; + int idx, enabled = 0; struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); if (!armpmu) @@ -601,9 +601,11 @@ static void armpmu_enable(struct pmu *pmu) continue; armpmu->enable(&event->hw, idx); + enabled = 1; } - armpmu->start(); + if (enabled) + armpmu->start(); } static void armpmu_disable(struct pmu *pmu) |