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 <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
index 736c1d9632dd554f545b74b3f0cd94f5fe9a120c..041e22bee839c0db2769adfd858891b1d0abb029 100644 (file)
--- 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();