sched: fix incorrect assumption that cpu 0 exists

This patch:

commit 9b5b77512dce239fa168183fa71896712232e95a
Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Date:   Mon Oct 15 17:00:09 2007 +0200

    sched: clean up code under CONFIG_FAIR_GROUP_SCHED

Introduced an assumption of the existence of CPU0 via this line

cfs_rq = tg->cfs_rq[0];

If you have no CPU0, that will be NULL.  The fix seems to be just to
take whatever cfs_rq queue comes out of the for_each_possible_cpu()
loop, since they're all equally good for the destruction operation.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 74dbb4020cf5..235952b100eb 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7041,7 +7041,7 @@ static void free_sched_group(struct rcu_head *rhp)
 /* Destroy runqueue etc associated with a task group */
 void sched_destroy_group(struct task_group *tg)
 {
-        struct cfs_rq *cfs_rq;
+        struct cfs_rq *cfs_rq = NULL;
         int i;
 
         for_each_possible_cpu(i) {
@@ -7049,7 +7049,7 @@ void sched_destroy_group(struct task_group *tg)
                 list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
         }
 
-        cfs_rq = tg->cfs_rq[0];
+        BUG_ON(!cfs_rq);
 
         /* wait for possible concurrent references to cfs_rqs complete */
         call_rcu(&cfs_rq->rcu, free_sched_group);