pkt_sched: Fix qdisc list locking
Since some qdiscs call qdisc_tree_decrease_qlen() (so qdisc_lookup())
without rtnl_lock(), adding and deleting from a qdisc list needs
additional locking. This patch adds global spinlock qdisc_list_lock
and wrapper functions for modifying the list. It is considered as a
temporary solution until hfsc_dequeue(), netem_dequeue() and
tbf_dequeue() (or qdisc_tree_decrease_qlen()) are redone.
With feedback from Herbert Xu and David S. Miller.
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index c3ed4d4..5f0ade7 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -526,10 +526,9 @@
!atomic_dec_and_test(&qdisc->refcnt))
return;
- if (qdisc->parent)
- list_del(&qdisc->list);
-
#ifdef CONFIG_NET_SCHED
+ qdisc_list_del(qdisc);
+
qdisc_put_stab(qdisc->stab);
#endif
gen_kill_estimator(&qdisc->bstats, &qdisc->rate_est);