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

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

[Anna-Maria Gleixner]

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_sf.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -1510,7 +1510,6 @@ static void cpumf_measurement_alert(stru
 static int cpumf_pmu_notifier(struct notifier_block *self,
 			      unsigned long action, void *hcpu)
 {
-	unsigned int cpu = (long) hcpu;
 	int flags;
 
 	/* Ignore the notification if no events are scheduled on the PMU.
@@ -1523,11 +1522,15 @@ static int cpumf_pmu_notifier(struct not
 	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;

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

[Heiko Carstens]

On Mon, May 02, 2016 at 11:00:12AM +0200, Anna-Maria Gleixner wrote:
> 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_sf.c |    9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)

Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>

Same here: Martin, can you pick this one up, please?

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

[Martin Schwidefsky]

On Mon, 2 May 2016 12:43:56 +0200
Heiko Carstens <heiko.carstens@de.ibm.com> wrote:

> On Mon, May 02, 2016 at 11:00:12AM +0200, Anna-Maria Gleixner wrote:
> > 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_sf.c |    9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
> 
> Same here: Martin, can you pick this one up, please?

Applied as well.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.