diff options
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.c | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index aa4e3a74e541..6be186ccef46 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -135,6 +135,7 @@ static int x86_pmu_extra_regs(u64 config, struct perf_event *event) } static atomic_t active_events; +static atomic_t pmc_refcount; static DEFINE_MUTEX(pmc_reserve_mutex); #ifdef CONFIG_X86_LOCAL_APIC @@ -271,6 +272,7 @@ msr_fail: static void hw_perf_event_destroy(struct perf_event *event) { x86_release_hardware(); + atomic_dec(&active_events); } void hw_perf_lbr_event_destroy(struct perf_event *event) @@ -324,16 +326,16 @@ int x86_reserve_hardware(void) { int err = 0; - if (!atomic_inc_not_zero(&active_events)) { + if (!atomic_inc_not_zero(&pmc_refcount)) { mutex_lock(&pmc_reserve_mutex); - if (atomic_read(&active_events) == 0) { + if (atomic_read(&pmc_refcount) == 0) { if (!reserve_pmc_hardware()) err = -EBUSY; else reserve_ds_buffers(); } if (!err) - atomic_inc(&active_events); + atomic_inc(&pmc_refcount); mutex_unlock(&pmc_reserve_mutex); } @@ -342,7 +344,7 @@ int x86_reserve_hardware(void) void x86_release_hardware(void) { - if (atomic_dec_and_mutex_lock(&active_events, &pmc_reserve_mutex)) { + if (atomic_dec_and_mutex_lock(&pmc_refcount, &pmc_reserve_mutex)) { release_pmc_hardware(); release_ds_buffers(); mutex_unlock(&pmc_reserve_mutex); @@ -371,12 +373,24 @@ int x86_add_exclusive(unsigned int what) out: mutex_unlock(&pmc_reserve_mutex); + + /* + * Assuming that all exclusive events will share the PMI handler + * (which checks active_events for whether there is work to do), + * we can bump active_events counter right here, except for + * x86_lbr_exclusive_lbr events that go through x86_pmu_event_init() + * path, which already bumps active_events for them. + */ + if (!ret && what != x86_lbr_exclusive_lbr) + atomic_inc(&active_events); + return ret; } void x86_del_exclusive(unsigned int what) { atomic_dec(&x86_pmu.lbr_exclusive[what]); + atomic_dec(&active_events); } int x86_setup_perfctr(struct perf_event *event) @@ -557,6 +571,7 @@ static int __x86_pmu_event_init(struct perf_event *event) if (err) return err; + atomic_inc(&active_events); event->destroy = hw_perf_event_destroy; event->hw.idx = -1; @@ -1429,6 +1444,10 @@ perf_event_nmi_handler(unsigned int cmd, struct pt_regs *regs) u64 finish_clock; int ret; + /* + * All PMUs/events that share this PMI handler should make sure to + * increment active_events for their events. + */ if (!atomic_read(&active_events)) return NMI_DONE; |