diff options
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/kernel/perf_counter.c | 47 |
1 files changed, 42 insertions, 5 deletions
diff --git a/arch/powerpc/kernel/perf_counter.c b/arch/powerpc/kernel/perf_counter.c index cde720fc495..560dd1e7b52 100644 --- a/arch/powerpc/kernel/perf_counter.c +++ b/arch/powerpc/kernel/perf_counter.c @@ -41,6 +41,8 @@ struct power_pmu *ppmu; */ static unsigned int freeze_counters_kernel = MMCR0_FCS; +static void perf_counter_interrupt(struct pt_regs *regs); + void perf_counter_print_debug(void) { } @@ -594,6 +596,24 @@ struct hw_perf_counter_ops power_perf_ops = { .read = power_perf_read }; +/* Number of perf_counters counting hardware events */ +static atomic_t num_counters; +/* Used to avoid races in calling reserve/release_pmc_hardware */ +static DEFINE_MUTEX(pmc_reserve_mutex); + +/* + * Release the PMU if this is the last perf_counter. + */ +static void hw_perf_counter_destroy(struct perf_counter *counter) +{ + if (!atomic_add_unless(&num_counters, -1, 1)) { + mutex_lock(&pmc_reserve_mutex); + if (atomic_dec_return(&num_counters) == 0) + release_pmc_hardware(); + mutex_unlock(&pmc_reserve_mutex); + } +} + const struct hw_perf_counter_ops * hw_perf_counter_init(struct perf_counter *counter) { @@ -601,6 +621,7 @@ hw_perf_counter_init(struct perf_counter *counter) struct perf_counter *ctrs[MAX_HWCOUNTERS]; unsigned int events[MAX_HWCOUNTERS]; int n; + int err; if (!ppmu) return NULL; @@ -646,6 +667,27 @@ hw_perf_counter_init(struct perf_counter *counter) counter->hw.config = events[n]; atomic64_set(&counter->hw.period_left, counter->hw_event.irq_period); + + /* + * See if we need to reserve the PMU. + * If no counters are currently in use, then we have to take a + * mutex to ensure that we don't race with another task doing + * reserve_pmc_hardware or release_pmc_hardware. + */ + err = 0; + if (!atomic_inc_not_zero(&num_counters)) { + mutex_lock(&pmc_reserve_mutex); + if (atomic_read(&num_counters) == 0 && + reserve_pmc_hardware(perf_counter_interrupt)) + err = -EBUSY; + else + atomic_inc(&num_counters); + mutex_unlock(&pmc_reserve_mutex); + } + counter->destroy = hw_perf_counter_destroy; + + if (err) + return NULL; return &power_perf_ops; } @@ -769,11 +811,6 @@ static int init_perf_counters(void) { unsigned long pvr; - if (reserve_pmc_hardware(perf_counter_interrupt)) { - printk(KERN_ERR "Couldn't init performance monitor subsystem\n"); - return -EBUSY; - } - /* XXX should get this from cputable */ pvr = mfspr(SPRN_PVR); switch (PVR_VER(pvr)) { |