[PATCH v2] s390/cpum_cf: Remove superfluous SMP function call

Anna-Maria Gleixner
2016-05-02T08:59:57Z

Since commit 3b9d6da67e11 ("cpu/hotplug: Fix rollback during error-out
in __cpu_disable()") it is ensured that callbacks of CPU_ONLINE and
CPU_DOWN_PREPARE are processed on the hotplugged CPU. Due to this SMP
function calls are no longer required.

Replace smp_call_function_single() with a direct call of
setup_pmc_cpu(). To keep the calling convention, interrupts are
explicitly disabled around the call.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
Changes in v2:
- Adapt referenced commit in commit message

arch/s390/kernel/perf_cpum_cf.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -665,18 +665,21 @@ static struct pmu cpumf_pmu = {
static int cpumf_pmu_notifier(struct notifier_block *self, unsigned long action,
void *hcpu)
{
- unsigned int cpu = (long) hcpu;
int flags;

switch (action & ~CPU_TASKS_FROZEN) {
case CPU_ONLINE:
case CPU_DOWN_FAILED:
flags = PMC_INIT;
- smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1);
+ local_irq_disable();
+ setup_pmc_cpu(&flags);
+ local_irq_enable();
break;
case CPU_DOWN_PREPARE:
flags = PMC_RELEASE;
- smp_call_function_single(cpu, setup_pmc_cpu, &flags, 1);
+ local_irq_disable();
+ setup_pmc_cpu(&flags);
+ local_irq_enable();
break;
default:
break;