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Subject[PATCH v3 09/35] drivers/perf: optimize ali_drw_get_counter_idx() by using find_and_set_bit()
Date
The function searches used_mask for a set bit in a for-loop bit by bit.
Simplify it by using atomic find_and_set_bit().

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Will Deacon <will@kernel.org>
---
drivers/perf/alibaba_uncore_drw_pmu.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/perf/alibaba_uncore_drw_pmu.c b/drivers/perf/alibaba_uncore_drw_pmu.c
index 19d459a36be5..2a3b7701d568 100644
--- a/drivers/perf/alibaba_uncore_drw_pmu.c
+++ b/drivers/perf/alibaba_uncore_drw_pmu.c
@@ -274,15 +274,9 @@ static const struct attribute_group *ali_drw_pmu_attr_groups[] = {
static int ali_drw_get_counter_idx(struct perf_event *event)
{
struct ali_drw_pmu *drw_pmu = to_ali_drw_pmu(event->pmu);
- int idx;
+ int idx = find_and_set_bit(drw_pmu->used_mask, ALI_DRW_PMU_COMMON_MAX_COUNTERS);

- for (idx = 0; idx < ALI_DRW_PMU_COMMON_MAX_COUNTERS; ++idx) {
- if (!test_and_set_bit(idx, drw_pmu->used_mask))
- return idx;
- }
-
- /* The counters are all in use. */
- return -EBUSY;
+ return idx < ALI_DRW_PMU_COMMON_MAX_COUNTERS ? idx : -EBUSY;
}

static u64 ali_drw_pmu_read_counter(struct perf_event *event)
--
2.40.1
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