* [PATCH v2] arm, hw-breakpoint: Remove superfluous SMP function call
@ 2016-04-06 8:40 Anna-Maria Gleixner
2016-04-07 11:34 ` Will Deacon
0 siblings, 1 reply; 2+ messages in thread
From: Anna-Maria Gleixner @ 2016-04-06 8:40 UTC (permalink / raw)
To: linux-kernel
Cc: rt, Anna-Maria Gleixner, Will Deacon, Mark Rutland, Russell King,
linux-arm-kernel
Since commit 1cf4f629d9d2 ("cpu/hotplug: Move online calls to
hotplugged cpu") 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
reset_ctrl_regs(). To keep the calling convention, interrupts are
explicitly disabled around the call.
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
arch/arm/kernel/hw_breakpoint.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -1023,8 +1023,11 @@ static void reset_ctrl_regs(void *unused
static int dbg_reset_notify(struct notifier_block *self,
unsigned long action, void *cpu)
{
- if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE)
- smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1);
+ if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE) {
+ local_irq_disable();
+ reset_ctrl_regs(NULL);
+ local_irq_enable();
+ }
return NOTIFY_OK;
}
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v2] arm, hw-breakpoint: Remove superfluous SMP function call
2016-04-06 8:40 [PATCH v2] arm, hw-breakpoint: Remove superfluous SMP function call Anna-Maria Gleixner
@ 2016-04-07 11:34 ` Will Deacon
0 siblings, 0 replies; 2+ messages in thread
From: Will Deacon @ 2016-04-07 11:34 UTC (permalink / raw)
To: Anna-Maria Gleixner
Cc: linux-kernel, rt, Mark Rutland, Russell King, linux-arm-kernel
On Wed, Apr 06, 2016 at 10:40:30AM +0200, Anna-Maria Gleixner wrote:
> Since commit 1cf4f629d9d2 ("cpu/hotplug: Move online calls to
> hotplugged cpu") 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
> reset_ctrl_regs(). To keep the calling convention, interrupts are
> explicitly disabled around the call.
>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Russell King <linux@arm.linux.org.uk>
> Cc: linux-arm-kernel@lists.infradead.org
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
> ---
> arch/arm/kernel/hw_breakpoint.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> --- a/arch/arm/kernel/hw_breakpoint.c
> +++ b/arch/arm/kernel/hw_breakpoint.c
> @@ -1023,8 +1023,11 @@ static void reset_ctrl_regs(void *unused
> static int dbg_reset_notify(struct notifier_block *self,
> unsigned long action, void *cpu)
> {
> - if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE)
> - smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1);
> + if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE) {
> + local_irq_disable();
> + reset_ctrl_regs(NULL);
> + local_irq_enable();
> + }
>
> return NOTIFY_OK;
> }
Acked-by: Will Deacon <will.deacon@arm.com>
Will
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