From 8a6fe8f21ec4f049a7b1fe120ad50a5065a9c7a8 Mon Sep 17 00:00:00 2001 From: Thomas Richter Date: Wed, 19 Jun 2024 16:01:11 +0200 Subject: [PATCH] s390/cpum_sf: Use refcount_t instead of atomic_t Replace atomic_t by refcount_t for reference counting of events. Signed-off-by: Thomas Richter Acked-by: Sumanth Korikkar Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Alexander Gordeev Signed-off-by: Vasily Gorbik --- arch/s390/kernel/perf_cpum_sf.c | 29 ++++++++++++----------------- 1 file changed, 12 insertions(+), 17 deletions(-) diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c index 736c1d9632dd..041e22bee839 100644 --- a/arch/s390/kernel/perf_cpum_sf.c +++ b/arch/s390/kernel/perf_cpum_sf.c @@ -585,7 +585,7 @@ static void extend_sampling_buffer(struct sf_buffer *sfb, } /* Number of perf events counting hardware events */ -static atomic_t num_events; +static refcount_t num_events; /* Used to avoid races in calling reserve/release_cpumf_hardware */ static DEFINE_MUTEX(pmc_reserve_mutex); @@ -644,10 +644,8 @@ static int reserve_pmc_hardware(void) static void hw_perf_event_destroy(struct perf_event *event) { /* Release PMC if this is the last perf event */ - if (!atomic_add_unless(&num_events, -1, 1)) { - mutex_lock(&pmc_reserve_mutex); - if (atomic_dec_return(&num_events) == 0) - release_pmc_hardware(); + if (refcount_dec_and_mutex_lock(&num_events, &pmc_reserve_mutex)) { + release_pmc_hardware(); mutex_unlock(&pmc_reserve_mutex); } } @@ -810,22 +808,19 @@ static int __hw_perf_event_init(struct perf_event *event) struct hws_qsi_info_block si; struct perf_event_attr *attr = &event->attr; struct hw_perf_event *hwc = &event->hw; - int cpu, err; + int cpu, err = 0; /* Reserve CPU-measurement sampling facility */ - err = 0; - if (!atomic_inc_not_zero(&num_events)) { - mutex_lock(&pmc_reserve_mutex); - if (atomic_read(&num_events) == 0 && reserve_pmc_hardware()) - err = -EBUSY; - else - atomic_inc(&num_events); - mutex_unlock(&pmc_reserve_mutex); + mutex_lock(&pmc_reserve_mutex); + if (!refcount_inc_not_zero(&num_events)) { + err = reserve_pmc_hardware(); + if (!err) + refcount_set(&num_events, 1); } - event->destroy = hw_perf_event_destroy; - + mutex_unlock(&pmc_reserve_mutex); if (err) goto out; + event->destroy = hw_perf_event_destroy; /* Access per-CPU sampling information (query sampling info) */ /* @@ -2143,7 +2138,7 @@ static int cpusf_pmu_setup(unsigned int cpu, int flags) /* Ignore the notification if no events are scheduled on the PMU. * This might be racy... */ - if (!atomic_read(&num_events)) + if (!refcount_read(&num_events)) return 0; local_irq_disable();