net: qdisc: use rcu prefix and silence sparse warnings

Add __rcu notation to qdisc handling by doing this we can make
smatch output more legible. And anyways some of the cases should
be using rcu_dereference() see qdisc_all_tx_empty(),
qdisc_tx_chainging(), and so on.

Also *wake_queue() API is commonly called from driver timer routines
without rcu lock or rtnl lock. So I added rcu_read_lock() blocks
around netif_wake_subqueue and netif_tx_wake_queue.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 5 deletions

diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c
index aaa8d03ed054..5cd291bd00e4 100644
--- a/net/sched/sch_teql.c
+++ b/net/sched/sch_teql.c
@@ -96,11 +96,14 @@ teql_dequeue(struct Qdisc *sch)
         struct teql_sched_data *dat = qdisc_priv(sch);
         struct netdev_queue *dat_queue;
         struct sk_buff *skb;
+        struct Qdisc *q;
 
         skb = __skb_dequeue(&dat->q);
         dat_queue = netdev_get_tx_queue(dat->m->dev, 0);
+        q = rcu_dereference_bh(dat_queue->qdisc);
+
         if (skb == NULL) {
-                struct net_device *m = qdisc_dev(dat_queue->qdisc);
+                struct net_device *m = qdisc_dev(q);
                 if (m) {
                         dat->m->slaves = sch;
                         netif_wake_queue(m);
@@ -108,7 +111,7 @@ teql_dequeue(struct Qdisc *sch)
         } else {
                 qdisc_bstats_update(sch, skb);
         }
-        sch->q.qlen = dat->q.qlen + dat_queue->qdisc->q.qlen;
+        sch->q.qlen = dat->q.qlen + q->q.qlen;
         return skb;
 }
 
@@ -157,9 +160,9 @@ teql_destroy(struct Qdisc *sch)
                                                 txq = netdev_get_tx_queue(master->dev, 0);
                                                 master->slaves = NULL;
 
-                                                root_lock = qdisc_root_sleeping_lock(txq->qdisc);
+                                                root_lock = qdisc_root_sleeping_lock(rtnl_dereference(txq->qdisc));
                                                 spin_lock_bh(root_lock);
-                                                qdisc_reset(txq->qdisc);
+                                                qdisc_reset(rtnl_dereference(txq->qdisc));
                                                 spin_unlock_bh(root_lock);
                                         }
                                 }
@@ -266,7 +269,7 @@ static inline int teql_resolve(struct sk_buff *skb,
         struct dst_entry *dst = skb_dst(skb);
         int res;
 
-        if (txq->qdisc == &noop_qdisc)
+        if (rcu_access_pointer(txq->qdisc) == &noop_qdisc)
                 return -ENODEV;
 
         if (!dev->header_ops || !dst)