linux-kernel - [PATCH v2] arm64: hw-breakpoint: Remove superfluous SMP function call

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Date:	Wed,  6 Apr 2016 10:42:49 +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>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	linux-arm-kernel@...ts.infradead.org
Subject: [PATCH v2] arm64: 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
hw_breakpoint_reset(). To keep the calling convention, interrupts are
explicitly disabled around the call.

Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will.deacon@....com>
Cc: linux-arm-kernel@...ts.infradead.org
Signed-off-by: Anna-Maria Gleixner <anna-maria@...utronix.de>
---
 arch/arm64/kernel/hw_breakpoint.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/arch/arm64/kernel/hw_breakpoint.c
+++ b/arch/arm64/kernel/hw_breakpoint.c
@@ -886,9 +886,11 @@ static int hw_breakpoint_reset_notify(st
 						unsigned long action,
 						void *hcpu)
 {
-	int cpu = (long)hcpu;
-	if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE)
-		smp_call_function_single(cpu, hw_breakpoint_reset, NULL, 1);
+	if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE) {
+		local_irq_disable();
+		hw_breakpoint_reset(NULL);
+		local_irq_enable();
+	}
 	return NOTIFY_OK;
 }