[PATCH net-next RESEND] sched: sfq: drop packets after root qdisc lock is released

[gfree . wind]

From: Gao Feng <gfree.w...@vip.163.com>

The commit 520ac30f4551 ("net_sched: drop packets after root qdisc lock
is released) made a big change of tc for performance. But there are
some points which are not changed in SFQ enqueue operation.
1. Fail to find the SFQ hash slot;
2. When the queue is full;

Now use qdisc_drop instead free skb directly.

Signed-off-by: Gao Feng <gfree.w...@vip.163.com>
---
 net/sched/sch_sfq.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index 82469ef..8841f4d 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -292,7 +292,7 @@ static inline void slot_queue_add(struct sfq_slot *slot, 
struct sk_buff *skb)
        slot->skblist_prev = skb;
 }
 
-static unsigned int sfq_drop(struct Qdisc *sch)
+static unsigned int sfq_drop(struct Qdisc *sch, struct sk_buff **to_free)
 {
        struct sfq_sched_data *q = qdisc_priv(sch);
        sfq_index x, d = q->cur_depth;
@@ -310,9 +310,13 @@ static unsigned int sfq_drop(struct Qdisc *sch)
                slot->backlog -= len;
                sfq_dec(q, x);
                sch->q.qlen--;
-               qdisc_qstats_drop(sch);
                qdisc_qstats_backlog_dec(sch, skb);
-               kfree_skb(skb);
+               if (likely(to_free)) {
+                       qdisc_drop(skb, sch, to_free);
+               } else {
+                       qdisc_qstats_drop(sch);
+                       kfree_skb(skb);
+               }
                return len;
        }
 
@@ -360,7 +364,7 @@ static int sfq_headdrop(const struct sfq_sched_data *q)
        if (hash == 0) {
                if (ret & __NET_XMIT_BYPASS)
                        qdisc_qstats_drop(sch);
-               kfree_skb(skb);
+               __qdisc_drop(skb, to_free);
                return ret;
        }
        hash--;
@@ -465,7 +469,7 @@ static int sfq_headdrop(const struct sfq_sched_data *q)
                return NET_XMIT_SUCCESS;
 
        qlen = slot->qlen;
-       dropped = sfq_drop(sch);
+       dropped = sfq_drop(sch, to_free);
        /* Return Congestion Notification only if we dropped a packet
         * from this flow.
         */
@@ -675,7 +679,7 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt)
 
        qlen = sch->q.qlen;
        while (sch->q.qlen > q->limit)
-               dropped += sfq_drop(sch);
+               dropped += sfq_drop(sch, NULL);
        qdisc_tree_reduce_backlog(sch, qlen - sch->q.qlen, dropped);
 
        del_timer(&q->perturb_timer);
-- 
1.9.1