sched: cpu hotplug fix

rq_attach_root() does a kfree() with the runqueue lock held.

That's not a very wise move, fix it.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 3 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index c1d0ed360088..410eec404133 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6944,20 +6944,26 @@ static void free_rootdomain(struct root_domain *rd)
 
 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
 {
+        struct root_domain *old_rd = NULL;
         unsigned long flags;
 
         spin_lock_irqsave(&rq->lock, flags);
 
         if (rq->rd) {
-                struct root_domain *old_rd = rq->rd;
+                old_rd = rq->rd;
 
                 if (cpumask_test_cpu(rq->cpu, old_rd->online))
                         set_rq_offline(rq);
 
                 cpumask_clear_cpu(rq->cpu, old_rd->span);
 
-                if (atomic_dec_and_test(&old_rd->refcount))
-                        free_rootdomain(old_rd);
+                /*
+                 * If we dont want to free the old_rt yet then
+                 * set old_rd to NULL to skip the freeing later
+                 * in this function:
+                 */
+                if (!atomic_dec_and_test(&old_rd->refcount))
+                        old_rd = NULL;
         }
 
         atomic_inc(&rd->refcount);
@@ -6968,6 +6974,9 @@ static void rq_attach_root(struct rq *rq, struct root_domain *rd)
                 set_rq_online(rq);
 
         spin_unlock_irqrestore(&rq->lock, flags);
+
+        if (old_rd)
+                free_rootdomain(old_rd);
 }
 
 static int __init_refok init_rootdomain(struct root_domain *rd, bool bootmem)