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Commit e6bde73b authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds
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cpu-hotplug: return better errno on cpu hotplug failure 



Currently, onlining or offlining a CPU failure by one of the cpu notifiers
error always cause -EINVAL error.  (i.e.  writing 0 or 1 to
/sys/devices/system/cpu/cpuX/online gets EINVAL)

To get better error reporting rather than always getting -EINVAL, This
changes cpu_notify() to return -errno value with notifier_to_errno() and
fix the callers.  Now that cpu notifiers can return encapsulate errno
value.

Currently, all cpu hotplug notifiers return NOTIFY_OK, NOTIFY_BAD, or
NOTIFY_DONE.  So cpu_notify() can returns 0 or -EPERM with this change for
now.

(notifier_to_errno(NOTIFY_OK) == 0, notifier_to_errno(NOTIFY_DONE) == 0,
notifier_to_errno(NOTIFY_BAD) == -EPERM)

Forthcoming patches convert several cpu notifiers to return encapsulate
errno value with notifier_from_errno().

Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e9fb7631

kernel/cpu.c

+8 −6
Original line number Diff line number Diff line
@@ -137,8 +137,12 @@ int __ref register_cpu_notifier(struct notifier_block *nb) 
static int __cpu_notify(unsigned long val, void *v, int nr_to_call,

			int *nr_calls)

{

	return __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,

	int ret;



	ret = __raw_notifier_call_chain(&cpu_chain, val, v, nr_to_call,

					nr_calls);



	return notifier_to_errno(ret);

}



static int cpu_notify(unsigned long val, void *v)
@@ -151,7 +155,7 @@ static void cpu_notify_nofail(unsigned long val, void *v) 
	int err;



	err = cpu_notify(val, v);

	BUG_ON(err == NOTIFY_BAD);

	BUG_ON(err);

}



#ifdef CONFIG_HOTPLUG_CPU
@@ -232,14 +236,13 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) 
	cpu_hotplug_begin();

	set_cpu_active(cpu, false);

	err = __cpu_notify(CPU_DOWN_PREPARE | mod, hcpu, -1, &nr_calls);

	if (err == NOTIFY_BAD) {

	if (err) {

		set_cpu_active(cpu, true);



		nr_calls--;

		__cpu_notify(CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL);

		printk("%s: attempt to take down CPU %u failed\n",

				__func__, cpu);

		err = -EINVAL;

		goto out_release;

	}
@@ -304,11 +307,10 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen) 


	cpu_hotplug_begin();

	ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);

	if (ret == NOTIFY_BAD) {

	if (ret) {

		nr_calls--;

		printk("%s: attempt to bring up CPU %u failed\n",

				__func__, cpu);

		ret = -EINVAL;

		goto out_notify;

	}