ARM: perf: Remove unnecessary armpmu->enable()s

Currently, armpmu_enable iterates through the events for a given
counter set, calling armpmu->enable on each before calling
armpmu->start to start the PMU's counters.

As armpmu->enable is called when each event is added, each event is
already configured in hardware. Due to this, calling armpmu->enable
in armpmu_enable is unnecessary and confusing.

This patch removes the unnecessary calls to armpmu->enable.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 2 insertions, 12 deletions

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index aaa631b8cbc2..e6e5d7c84f1a 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -12,6 +12,7 @@
  */
 #define pr_fmt(fmt) "hw perfevents: " fmt
 
+#include <linux/bitmap.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -557,20 +558,9 @@ static int armpmu_event_init(struct perf_event *event)
 
 static void armpmu_enable(struct pmu *pmu)
 {
-        /* Enable all of the perf events on hardware. */
         struct arm_pmu *armpmu = to_arm_pmu(pmu);
-        int idx, enabled = 0;
         struct pmu_hw_events *hw_events = armpmu->get_hw_events();
-
-        for (idx = 0; idx < armpmu->num_events; ++idx) {
-                struct perf_event *event = hw_events->events[idx];
-
-                if (!event)
-                        continue;
-
-                armpmu->enable(&event->hw, idx);
-                enabled = 1;
-        }
+        int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events);
 
         if (enabled)
                 armpmu->start();