net_sched: introduce qdisc_replace() helper

Remove nearly duplicated code and prepare for the following patch.

Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 0 deletions

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 636a362a0e03..8fdad9f7a2fb 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -707,6 +707,23 @@ static inline void qdisc_reset_queue(struct Qdisc *sch)
         sch->qstats.backlog = 0;
 }
 
+static inline struct Qdisc *qdisc_replace(struct Qdisc *sch, struct Qdisc *new,
+                                          struct Qdisc **pold)
+{
+        struct Qdisc *old;
+
+        sch_tree_lock(sch);
+        old = *pold;
+        *pold = new;
+        if (old != NULL) {
+                qdisc_tree_decrease_qlen(old, old->q.qlen);
+                qdisc_reset(old);
+        }
+        sch_tree_unlock(sch);
+
+        return old;
+}
+
 static inline unsigned int __qdisc_queue_drop(struct Qdisc *sch,
                                               struct sk_buff_head *list)
 {