Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ba77813a authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: x86: fixup nmi_watchdog vs perf_counter boo-boo 



Invert the atomic_inc_not_zero() test so that we will indeed detect the
first activation.

Also rename the global num_counters, since its easy to confuse with
x86_pmu.num_counters.

[ Impact: fix non-working perfcounters on AMD CPUs, cleanup ]

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1241455664.7620.4938.camel@twins>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent b82914ce

arch/x86/kernel/cpu/perf_counter.c

+7 −7
Original line number Diff line number Diff line
@@ -171,7 +171,7 @@ x86_perf_counter_update(struct perf_counter *counter, 
	return new_raw_count;

}



static atomic_t num_counters;

static atomic_t active_counters;

static DEFINE_MUTEX(pmc_reserve_mutex);



static bool reserve_pmc_hardware(void)
@@ -224,7 +224,7 @@ static void release_pmc_hardware(void) 


static void hw_perf_counter_destroy(struct perf_counter *counter)

{

	if (atomic_dec_and_mutex_lock(&num_counters, &pmc_reserve_mutex)) {

	if (atomic_dec_and_mutex_lock(&active_counters, &pmc_reserve_mutex)) {

		release_pmc_hardware();

		mutex_unlock(&pmc_reserve_mutex);

	}
@@ -248,12 +248,12 @@ static int __hw_perf_counter_init(struct perf_counter *counter) 
		return -ENODEV;



	err = 0;

	if (atomic_inc_not_zero(&num_counters)) {

	if (!atomic_inc_not_zero(&active_counters)) {

		mutex_lock(&pmc_reserve_mutex);

		if (atomic_read(&num_counters) == 0 && !reserve_pmc_hardware())

		if (atomic_read(&active_counters) == 0 && !reserve_pmc_hardware())

			err = -EBUSY;

		else

			atomic_inc(&num_counters);

			atomic_inc(&active_counters);

		mutex_unlock(&pmc_reserve_mutex);

	}

	if (err)
@@ -871,7 +871,7 @@ perf_counter_nmi_handler(struct notifier_block *self, 
	struct pt_regs *regs;

	int ret;



	if (!atomic_read(&num_counters))

	if (!atomic_read(&active_counters))

		return NOTIFY_DONE;



	switch (cmd) {