linux-kernel - [PATCH 18/20] x86/oprofile/nmi: Remove superfluous smp_function_call

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Message-Id: <20161117183541.8588-19-bigeasy@linutronix.de>
Date:   Thu, 17 Nov 2016 19:35:39 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     rt@...uxtronix.de, Anna-Maria Gleixner <anna-maria@...utronix.de>,
        Robert Richter <rric@...nel.org>, x86@...nel.org,
        oprofile-list@...ts.sf.net,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 18/20] x86/oprofile/nmi: Remove superfluous smp_function_call_single()

From: Anna-Maria Gleixner <anna-maria@...utronix.de>

Since commit 1cf4f629d9d2 ("cpu/hotplug: Move online calls to
hotplugged cpu") the CPU_ONLINE and CPU_DOWN_PREPARE notifiers are
always run on the hot plugged CPU, and as of commit 3b9d6da67e11
("cpu/hotplug: Fix rollback during error-out in __cpu_disable()")
the CPU_DOWN_FAILED notifier also runs on the hot plugged CPU.
This patch converts the SMP functional calls into direct calls.

smp_call_function_single() executes the function with interrupts
disabled. This calling convention is preserved.

Cc: Robert Richter <rric@...nel.org>
Cc: x86@...nel.org
Cc: oprofile-list@...ts.sf.net
Signed-off-by: Anna-Maria Gleixner <anna-maria@...utronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 arch/x86/oprofile/nmi_int.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/arch/x86/oprofile/nmi_int.c b/arch/x86/oprofile/nmi_int.c
index 28c04123b6dd..c39172cd6c87 100644
--- a/arch/x86/oprofile/nmi_int.c
+++ b/arch/x86/oprofile/nmi_int.c
@@ -387,20 +387,24 @@ static void nmi_cpu_shutdown(void *dummy)
 	nmi_cpu_restore_registers(msrs);
 }
 
-static void nmi_cpu_up(void *dummy)
+static void nmi_cpu_up(void)
 {
+	local_irq_disable();
 	if (nmi_enabled)
-		nmi_cpu_setup(dummy);
+		nmi_cpu_setup(NULL);
 	if (ctr_running)
-		nmi_cpu_start(dummy);
+		nmi_cpu_start(NULL);
+	local_irq_enable();
 }
 
-static void nmi_cpu_down(void *dummy)
+static void nmi_cpu_down(void)
 {
+	local_irq_disable();
 	if (ctr_running)
-		nmi_cpu_stop(dummy);
+		nmi_cpu_stop(NULL);
 	if (nmi_enabled)
-		nmi_cpu_shutdown(dummy);
+		nmi_cpu_shutdown(NULL);
+	local_irq_enable();
 }
 
 static int nmi_create_files(struct dentry *root)
@@ -436,15 +440,13 @@ static int nmi_create_files(struct dentry *root)
 static int oprofile_cpu_notifier(struct notifier_block *b, unsigned long action,
 				 void *data)
 {
-	int cpu = (unsigned long)data;
-
 	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_DOWN_FAILED:
 	case CPU_ONLINE:
-		smp_call_function_single(cpu, nmi_cpu_up, NULL, 0);
+		nmi_cpu_up();
 		break;
 	case CPU_DOWN_PREPARE:
-		smp_call_function_single(cpu, nmi_cpu_down, NULL, 1);
+		nmi_cpu_down();
 		break;
 	}
 	return NOTIFY_DONE;
-- 
2.10.2