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 <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
mna · May 24, 2007 · 72fcde9 · 72fcde9
1 parent 88f18ba
commit 72fcde9
Showing 1 changed file with 12 additions and 5 deletions.
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
@@ -243,11 +243,18 @@ void tick_broadcast_on_off(unsigned long reason, int *oncpu)
 {
 	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();
 }