Ignore bogus ACPI info for offline CPUs
Booting a SMP kernel with maxcpus=1 on a SMP system leads to a hard hang,
because ACPI ignores the maxcpus setting and sends timer broadcast info for
the offline CPUs. This results in a stuck for ever call to
smp_call_function_single() on an offline CPU.
Ignore the bogus information and print a kernel error to remind ACPI
folks to fix it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index eadfce2..8001d37 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -243,11 +243,18 @@
{
int cpu = get_cpu();
- if (cpu == *oncpu)
- tick_do_broadcast_on_off(&reason);
- else
- smp_call_function_single(*oncpu, tick_do_broadcast_on_off,
- &reason, 1, 1);
+ if (!cpu_isset(*oncpu, cpu_online_map)) {
+ printk(KERN_ERR "tick-braodcast: ignoring broadcast for "
+ "offline CPU #%d\n", *oncpu);
+ } else {
+
+ if (cpu == *oncpu)
+ tick_do_broadcast_on_off(&reason);
+ else
+ smp_call_function_single(*oncpu,
+ tick_do_broadcast_on_off,
+ &reason, 1, 1);
+ }
put_cpu();
}