pkt_sched: Don't hold qdisc lock over qdisc_destroy().
Based upon reports by Denys Fedoryshchenko, and feedback
and help from Jarek Poplawski and Herbert Xu.
We always either:
1) Never made an external reference to this qdisc.
or
2) Did a dev_deactivate() which purged all asynchronous
references.
So do not lock the qdisc when we call qdisc_destroy(),
it's illegal anyways as when we drop the lock this is
free'd memory.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 7d7070b..d91a233 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -638,11 +638,8 @@
if (new || old)
qdisc_notify(skb, n, clid, old, new);
- if (old) {
- sch_tree_lock(old);
+ if (old)
qdisc_destroy(old);
- sch_tree_unlock(old);
- }
}
/* Graft qdisc "new" to class "classid" of qdisc "parent" or
@@ -1092,16 +1089,10 @@
graft:
if (1) {
- spinlock_t *root_lock;
-
err = qdisc_graft(dev, p, skb, n, clid, q, NULL);
if (err) {
- if (q) {
- root_lock = qdisc_root_lock(q);
- spin_lock_bh(root_lock);
+ if (q)
qdisc_destroy(q);
- spin_unlock_bh(root_lock);
- }
return err;
}
}