cpu-hotplug: return better errno on cpu hotplug failure (e6bde73b) · Commits · 戴 / test

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:

Akinobu Mita <akinobu.mita@gmail.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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;
		}

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