linux-kernel - [PATCH v2] arm, hw-breakpoint: Remove superfluous SMP function call

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Date:	Wed,  6 Apr 2016 10:40:30 +0200
From:	Anna-Maria Gleixner <anna-maria@...utronix.de>
To:	linux-kernel@...r.kernel.org
Cc:	rt@...utronix.de, Anna-Maria Gleixner <anna-maria@...utronix.de>,
	Will Deacon <will.deacon@....com>,
	Mark Rutland <mark.rutland@....com>,
	Russell King <linux@....linux.org.uk>,
	linux-arm-kernel@...ts.infradead.org
Subject: [PATCH v2] arm, hw-breakpoint: Remove superfluous SMP function call

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@....com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Russell King <linux@....linux.org.uk>
Cc: linux-arm-kernel@...ts.infradead.org
Signed-off-by: Anna-Maria Gleixner <anna-maria@...utronix.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;
 }