[PATCH] ledtrig-cpu: Handle CPU hot(un)plugging

[PATCH] ledtrig-cpu: Handle CPU hot(un)plugging

[Pawel Moll]

When CPU is hot(un)plugged, no syscore notification is being
generated, nor is cpuidle involved. This leaves the CPU LED
turned on, because the dying thread is doing some work (LED on)
and than it is... well, dying (LED still on :-)

Added notifier block for hot(un)plugging operations, generating
existing trigger events.

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
---
 drivers/leds/trigger/ledtrig-cpu.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/leds/trigger/ledtrig-cpu.c b/drivers/leds/trigger/ledtrig-cpu.c
index 118335e..1c3ee9f 100644
--- a/drivers/leds/trigger/ledtrig-cpu.c
+++ b/drivers/leds/trigger/ledtrig-cpu.c
@@ -26,6 +26,7 @@
 #include <linux/percpu.h>
 #include <linux/syscore_ops.h>
 #include <linux/rwsem.h>
+#include <linux/cpu.h>
 #include "../leds.h"
 
 #define MAX_NAME_LEN	8
@@ -92,6 +93,26 @@ static struct syscore_ops ledtrig_cpu_syscore_ops = {
 	.resume		= ledtrig_cpu_syscore_resume,
 };
 
+static int ledtrig_cpu_notify(struct notifier_block *self,
+					   unsigned long action, void *hcpu)
+{
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_STARTING:
+		ledtrig_cpu(CPU_LED_START);
+		break;
+	case CPU_DYING:
+		ledtrig_cpu(CPU_LED_STOP);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+
+static struct notifier_block ledtrig_cpu_nb = {
+	.notifier_call = ledtrig_cpu_notify,
+};
+
 static int __init ledtrig_cpu_init(void)
 {
 	int cpu;
@@ -113,6 +134,7 @@ static int __init ledtrig_cpu_init(void)
 	}
 
 	register_syscore_ops(&ledtrig_cpu_syscore_ops);
+	register_cpu_notifier(&ledtrig_cpu_nb);
 
 	pr_info("ledtrig-cpu: registered to indicate activity on CPUs\n");
 
@@ -124,6 +146,8 @@ static void __exit ledtrig_cpu_exit(void)
 {
 	int cpu;
 
+	unregister_cpu_notifier(&ledtrig_cpu_nb);
+
 	for_each_possible_cpu(cpu) {
 		struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
 
-- 
1.8.3.2

Re: [PATCH] ledtrig-cpu: Handle CPU hot(un)plugging

[Pawel Moll]

On Wed, 2014-01-22 at 16:32 +0000, Pawel Moll wrote:
> When CPU is hot(un)plugged, no syscore notification is being
> generated, nor is cpuidle involved. This leaves the CPU LED
> turned on, because the dying thread is doing some work (LED on)
> and than it is... well, dying (LED still on :-)
> 
> Added notifier block for hot(un)plugging operations, generating
> existing trigger events.
> 
> Signed-off-by: Pawel Moll <pawel.moll@arm.com>

This is just a friendly and polite ping :-)

Pawel

Re: [PATCH] ledtrig-cpu: Handle CPU hot(un)plugging

[Bryan Wu]

On Thu, Feb 6, 2014 at 9:06 AM, Pawel Moll <pawel.moll@arm.com> wrote:
> On Wed, 2014-01-22 at 16:32 +0000, Pawel Moll wrote:
>> When CPU is hot(un)plugged, no syscore notification is being
>> generated, nor is cpuidle involved. This leaves the CPU LED
>> turned on, because the dying thread is doing some work (LED on)
>> and than it is... well, dying (LED still on :-)
>>
>> Added notifier block for hot(un)plugging operations, generating
>> existing trigger events.
>>
>> Signed-off-by: Pawel Moll <pawel.moll@arm.com>
>
> This is just a friendly and polite ping :-)
>

Just back from a vacation recently, start to catch up patch emails, :-)
This patch looks good to me, I will merge it.

Thanks,
-Bryan