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authorWill Deacon <will.deacon@arm.com>2011-07-01 14:38:12 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-07-05 12:37:23 +0100
commitf4f38430c94c38187db73a2cf3892cc8b12a2713 (patch)
treee8101e5202bfe600f928f3f2400dfd5afa4b54f6 /arch/arm
parent178783622ce0fd629fad21b33b8f8f56b64c5e45 (diff)
ARM: 6989/1: perf: do not start the PMU when no events are present
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. Cc: <stable@kernel.org> 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>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/kernel/perf_event.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index d53c0abc4dd..2b5b1421596 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -583,7 +583,7 @@ 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)
@@ -596,9 +596,11 @@ 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)