ARM: 6989/1: perf: do not start the PMU when no events are
commit64779cb190a6ba7a03b658cd0584cef74fb9c208
authorWill Deacon <will.deacon@arm.com>
Fri, 1 Jul 2011 13:38:12 +0000 (1 14:38 +0100)
committerAndi Kleen <ak@linux.intel.com>
Mon, 1 Aug 2011 20:55:04 +0000 (1 13:55 -0700)
tree624050de234886de90dbfe91dab403819fca0ac9
parent225686544fb9af569ea70a46e11fe130c6da5bd2
ARM: 6989/1: perf: do not start the PMU when no events are

[ upstream commit f4f38430c94c38187db73a2cf3892cc8b12a2713 ]
 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>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
arch/arm/kernel/perf_event.c