[PATCH 3.16 190/305] net_sched: introduce qdisc_replace() helper

[Ben Hutchings]

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: WANG Cong <xiyou.wangcong@xxxxxxxxx>

commit 86a7996cc8a078793670d82ed97d5a99bb4e8496 upstream.

Remove nearly duplicated code and prepare for the following patch.

Cc: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Acked-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 include/net/sch_generic.h | 17 +++++++++++++++++
 net/sched/sch_cbq.c       |  7 +------
 net/sched/sch_drr.c       |  6 +-----
 net/sched/sch_dsmark.c    |  8 +-------
 net/sched/sch_hfsc.c      |  6 +-----
 net/sched/sch_htb.c       |  9 +--------
 net/sched/sch_multiq.c    |  8 +-------
 net/sched/sch_netem.c     | 10 +---------
 net/sched/sch_prio.c      |  8 +-------
 net/sched/sch_qfq.c       |  6 +-----
 net/sched/sch_red.c       |  7 +------
 net/sched/sch_sfb.c       |  7 +------
 net/sched/sch_tbf.c       |  8 +-------
 13 files changed, 29 insertions(+), 78 deletions(-)

--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -608,6 +608,23 @@ static inline void qdisc_reset_queue(str
 	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)
 {
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -1643,13 +1643,8 @@ static int cbq_graft(struct Qdisc *sch,
 			new->reshape_fail = cbq_reshape_fail;
 #endif
 	}
-	sch_tree_lock(sch);
-	*old = cl->q;
-	cl->q = new;
-	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
-	qdisc_reset(*old);
-	sch_tree_unlock(sch);
 
+	*old = qdisc_replace(sch, new, &cl->q);
 	return 0;
 }
 
--- a/net/sched/sch_drr.c
+++ b/net/sched/sch_drr.c
@@ -224,11 +224,7 @@ static int drr_graft_class(struct Qdisc
 			new = &noop_qdisc;
 	}
 
-	sch_tree_lock(sch);
-	drr_purge_queue(cl);
-	*old = cl->qdisc;
-	cl->qdisc = new;
-	sch_tree_unlock(sch);
+	*old = qdisc_replace(sch, new, &cl->qdisc);
 	return 0;
 }
 
--- a/net/sched/sch_dsmark.c
+++ b/net/sched/sch_dsmark.c
@@ -67,13 +67,7 @@ static int dsmark_graft(struct Qdisc *sc
 			new = &noop_qdisc;
 	}
 
-	sch_tree_lock(sch);
-	*old = p->q;
-	p->q = new;
-	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
-	qdisc_reset(*old);
-	sch_tree_unlock(sch);
-
+	*old = qdisc_replace(sch, new, &p->q);
 	return 0;
 }
 
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -1212,11 +1212,7 @@ hfsc_graft_class(struct Qdisc *sch, unsi
 			new = &noop_qdisc;
 	}
 
-	sch_tree_lock(sch);
-	hfsc_purge_queue(sch, cl);
-	*old = cl->qdisc;
-	cl->qdisc = new;
-	sch_tree_unlock(sch);
+	*old = qdisc_replace(sch, new, &cl->qdisc);
 	return 0;
 }
 
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1164,14 +1164,7 @@ static int htb_graft(struct Qdisc *sch,
 				     cl->common.classid)) == NULL)
 		return -ENOBUFS;
 
-	sch_tree_lock(sch);
-	*old = cl->un.leaf.q;
-	cl->un.leaf.q = new;
-	if (*old != NULL) {
-		qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
-		qdisc_reset(*old);
-	}
-	sch_tree_unlock(sch);
+	*old = qdisc_replace(sch, new, &cl->un.leaf.q);
 	return 0;
 }
 
--- a/net/sched/sch_multiq.c
+++ b/net/sched/sch_multiq.c
@@ -302,13 +302,7 @@ static int multiq_graft(struct Qdisc *sc
 	if (new == NULL)
 		new = &noop_qdisc;
 
-	sch_tree_lock(sch);
-	*old = q->queues[band];
-	q->queues[band] = new;
-	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
-	qdisc_reset(*old);
-	sch_tree_unlock(sch);
-
+	*old = qdisc_replace(sch, new, &q->queues[band]);
 	return 0;
 }
 
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -1050,15 +1050,7 @@ static int netem_graft(struct Qdisc *sch
 {
 	struct netem_sched_data *q = qdisc_priv(sch);
 
-	sch_tree_lock(sch);
-	*old = q->qdisc;
-	q->qdisc = new;
-	if (*old) {
-		qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
-		qdisc_reset(*old);
-	}
-	sch_tree_unlock(sch);
-
+	*old = qdisc_replace(sch, new, &q->qdisc);
 	return 0;
 }
 
--- a/net/sched/sch_prio.c
+++ b/net/sched/sch_prio.c
@@ -266,13 +266,7 @@ static int prio_graft(struct Qdisc *sch,
 	if (new == NULL)
 		new = &noop_qdisc;
 
-	sch_tree_lock(sch);
-	*old = q->queues[band];
-	q->queues[band] = new;
-	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
-	qdisc_reset(*old);
-	sch_tree_unlock(sch);
-
+	*old = qdisc_replace(sch, new, &q->queues[band]);
 	return 0;
 }
 
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -616,11 +616,7 @@ static int qfq_graft_class(struct Qdisc
 			new = &noop_qdisc;
 	}
 
-	sch_tree_lock(sch);
-	qfq_purge_queue(cl);
-	*old = cl->qdisc;
-	cl->qdisc = new;
-	sch_tree_unlock(sch);
+	*old = qdisc_replace(sch, new, &cl->qdisc);
 	return 0;
 }
 
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -313,12 +313,7 @@ static int red_graft(struct Qdisc *sch,
 	if (new == NULL)
 		new = &noop_qdisc;
 
-	sch_tree_lock(sch);
-	*old = q->qdisc;
-	q->qdisc = new;
-	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
-	qdisc_reset(*old);
-	sch_tree_unlock(sch);
+	*old = qdisc_replace(sch, new, &q->qdisc);
 	return 0;
 }
 
--- a/net/sched/sch_sfb.c
+++ b/net/sched/sch_sfb.c
@@ -612,12 +612,7 @@ static int sfb_graft(struct Qdisc *sch,
 	if (new == NULL)
 		new = &noop_qdisc;
 
-	sch_tree_lock(sch);
-	*old = q->qdisc;
-	q->qdisc = new;
-	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
-	qdisc_reset(*old);
-	sch_tree_unlock(sch);
+	*old = qdisc_replace(sch, new, &q->qdisc);
 	return 0;
 }
 
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -501,13 +501,7 @@ static int tbf_graft(struct Qdisc *sch,
 	if (new == NULL)
 		new = &noop_qdisc;
 
-	sch_tree_lock(sch);
-	*old = q->qdisc;
-	q->qdisc = new;
-	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
-	qdisc_reset(*old);
-	sch_tree_unlock(sch);
-
+	*old = qdisc_replace(sch, new, &q->qdisc);
 	return 0;
 }