From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 23 May 2007 20:57:30 +0000 (-0700)
Subject: Ignore bogus ACPI info for offline CPUs
X-Git-Tag: v3.12-rc1~29350
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=72fcde966252abd17d70e4e216a0411a34523a8f;p=kernel%2Fkernel-generic.git

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 @@ 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();
 }