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: 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>
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 09207c7..0690ac2 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -137,8 +137,12 @@
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 @@
int err;
err = cpu_notify(val, v);
- BUG_ON(err == NOTIFY_BAD);
+ BUG_ON(err);
}
#ifdef CONFIG_HOTPLUG_CPU
@@ -232,14 +236,13 @@
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 @@
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;
}