[PATCH][2.5] Don't schedule tasks on offline cpus

[Zwane Mwaikambo]

We don't want to allow a cpu going offline to keep doing scheduler work so 
let it exit early, otherwise we'd keep pulling in tasks every timer tick.

diff -u -r1.1.1.1 sched.c
--- linux-2.5.61-trojan/kernel/sched.c	15 Feb 2003 12:32:44 -0000	1.1.1.1
+++ linux-2.5.61-trojan/kernel/sched.c	15 Feb 2003 16:04:51 -0000
@@ -939,6 +948,11 @@
 	struct list_head *head, *curr;
 	task_t *tmp;
 
+	/* CPU going down is a special case: we don't pull more tasks
+	   onboard */
+	if (unlikely(!cpu_online(this_cpu)))
+		goto out;
+
 	busiest = find_busiest_queue(this_rq, this_cpu, idle, &imbalance,
 					cpus_to_balance(this_cpu, this_rq));
 	if (!busiest)