"reboot" detection ...

[ratheesh kannoth]

Hi,

Is there any way to find that the machine is rebooting. ?

Say, i issued a "reboot" command in one of the Konsole shell. Is
there any way to detect this trigger in kernel space or in userspace ?
Any clue is really appreciated .

Thanks,
Ratheesh
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[Peter Hüwe]

Post by ratheesh kannoth
Is there any way to find that the machine is rebooting. ?
Say, i issued a "reboot" command in one of the Konsole shell. Is
there any way to detect this trigger in kernel space or in userspace ?
Any clue is really appreciated .

Hi ratheesh,

in the kernel it's pretty easy.
Simply use register_reboot_notifier from kernel/sys.c and you'll get notified
(via a callback you register) when the system gets rebooted.

You can use this stub driver as a reference (not actually tested):
---
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/reboot.h>

static int my_reboot_callback(struct notifier_block *self,
unsigned long val,
void *data){
if (val == SYS_RESTART)
pr_debug("We're rebooting\n");
return NOTIFY_DONE;
}

static struct notifier_block my_reboot_notifier = {
.notifier_call = my_reboot_callback,
};

static int __init my_reboot_init(void)
{
return register_reboot_notifier(&my_reboot_notifier);
}

static void __exit my_reboot_exit(void)
{
register_reboot_notifier(&my_reboot_notifier);
}

module_init(my_reboot_init);
module_exit(my_reboot_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Peter Huewe <***@gmx.de>");

---
regards,
Peter

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[Anatoly Sivov]

Post by Peter Hüwe
static void __exit my_reboot_exit(void)
{
register_reboot_notifier(&my_reboot_notifier);
}

Surely, this one should call unregister_reboot_notifier.
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[Peter Hüwe]

Post by Anatoly Sivov

Post by Peter Hüwe
static void __exit my_reboot_exit(void)
{
register_reboot_notifier(&my_reboot_notifier);
}

Surely, this one should call unregister_reboot_notifier.

Hehe, yes. This was just a test to see if you pay attention.

Peter

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