linux-kernel - [PATCH 4/5] oprofile: nmi-timer: Handle the FROZEN hot plug notifier actions.

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Date:	Fri, 18 Mar 2016 22:26:10 +0100
From:	Richard Cochran <rcochran@...utronix.de>
To:	<linux-kernel@...r.kernel.org>
Cc:	<rt@...utronix.de>, Robert Richter <rric@...nel.org>,
	oprofile-list@...ts.sf.net
Subject: [PATCH 4/5] oprofile: nmi-timer: Handle the FROZEN hot plug notifier actions.

When performing a suspend operation, the kernel brings all of the
non-boot CPUs offline, calling the hot plug notifiers with the flag,
CPU_TASKS_FROZEN, set in the action code.  Similarly, during resume,
the CPUs are brought back online, but again the notifiers have the
FROZEN flag set.

While some very few drivers really need to treat suspend/resume
specially, this driver unintentionally ignores the notifications.

This patch changes the driver to react to the FROZEN hot plug events.
As a result, the NMI timer is no longer left running during the
suspended state.

Cc: Robert Richter <rric@...nel.org>
Cc: oprofile-list@...ts.sf.net
Signed-off-by: Richard Cochran <rcochran@...utronix.de>
---
 drivers/oprofile/nmi_timer_int.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/oprofile/nmi_timer_int.c b/drivers/oprofile/nmi_timer_int.c
index 9559829..37ae173 100644
--- a/drivers/oprofile/nmi_timer_int.c
+++ b/drivers/oprofile/nmi_timer_int.c
@@ -63,7 +63,7 @@ static int nmi_timer_cpu_notifier(struct notifier_block *b, unsigned long action
 				  void *data)
 {
 	int cpu = (unsigned long)data;
-	switch (action) {
+	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_DOWN_FAILED:
 	case CPU_ONLINE:
 		nmi_timer_start_cpu(cpu);
-- 
2.1.4