Commit 72fcde96 authored May 23, 2007 by Thomas Gleixner Committed by Linus Torvalds May 23, 2007

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>

parent 88f18ba0

kernel/time/tick-broadcast.c

+12 −5

Original line number	Diff line number	Diff line
		@@ -243,11 +243,18 @@ void tick_broadcast_on_off(unsigned long reason, int *oncpu)
		{
		int cpu = get_cpu();

		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,
		smp_call_function_single(*oncpu,
		tick_do_broadcast_on_off,
		&reason, 1, 1);
		}
		put_cpu();
		}