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s390/cpum_sf: Use refcount_t instead of atomic_t

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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>
This commit is contained in:
Thomas Richter 2024-06-19 16:01:11 +02:00 committed by Vasily Gorbik
parent de9c2c66ad
commit 8a6fe8f21e
1 changed files with 12 additions and 17 deletions
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29
arch/s390/kernel/perf_cpum_sf.c
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@ -585,7 +585,7 @@ static void extend_sampling_buffer(struct sf_buffer *sfb,
} }
/* Number of perf events counting hardware events */ /* 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 */ /* Used to avoid races in calling reserve/release_cpumf_hardware */
static DEFINE_MUTEX(pmc_reserve_mutex); 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) static void hw_perf_event_destroy(struct perf_event *event)
{ {
/* Release PMC if this is the last perf event */ /* Release PMC if this is the last perf event */
if (!atomic_add_unless(&num_events, -1, 1)) { if (refcount_dec_and_mutex_lock(&num_events, &pmc_reserve_mutex)) {
mutex_lock(&pmc_reserve_mutex); release_pmc_hardware();
if (atomic_dec_return(&num_events) == 0)
release_pmc_hardware();
mutex_unlock(&pmc_reserve_mutex); 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 hws_qsi_info_block si;
struct perf_event_attr *attr = &event->attr; struct perf_event_attr *attr = &event->attr;
struct hw_perf_event *hwc = &event->hw; struct hw_perf_event *hwc = &event->hw;
int cpu, err; int cpu, err = 0;
/* Reserve CPU-measurement sampling facility */ /* Reserve CPU-measurement sampling facility */
err = 0; mutex_lock(&pmc_reserve_mutex);
if (!atomic_inc_not_zero(&num_events)) { if (!refcount_inc_not_zero(&num_events)) {
mutex_lock(&pmc_reserve_mutex); err = reserve_pmc_hardware();
if (atomic_read(&num_events) == 0 && reserve_pmc_hardware()) if (!err)
err = -EBUSY; refcount_set(&num_events, 1);
else
atomic_inc(&num_events);
mutex_unlock(&pmc_reserve_mutex);
} }
event->destroy = hw_perf_event_destroy; mutex_unlock(&pmc_reserve_mutex);
if (err) if (err)
goto out; goto out;
event->destroy = hw_perf_event_destroy;
/* Access per-CPU sampling information (query sampling info) */ /* 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. /* Ignore the notification if no events are scheduled on the PMU.
* This might be racy... * This might be racy...
*/ */
if (!atomic_read(&num_events)) if (!refcount_read(&num_events))
return 0; return 0;
local_irq_disable(); local_irq_disable();