1 files changed, 35 insertions, 0 deletions

diff --git a/net/sched/sch_fifo.c b/net/sched/sch_fifo.c
index 69188e8358b4..5948bafa8ce2 100644
--- a/net/sched/sch_fifo.c
+++ b/net/sched/sch_fifo.c
@@ -10,6 +10,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
@@ -43,6 +44,26 @@ static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch)
         return qdisc_reshape_fail(skb, sch);
 }
 
+static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc* sch)
+{
+        struct sk_buff *skb_head;
+        struct fifo_sched_data *q = qdisc_priv(sch);
+
+        if (likely(skb_queue_len(&sch->q) < q->limit))
+                return qdisc_enqueue_tail(skb, sch);
+
+        /* queue full, remove one skb to fulfill the limit */
+        skb_head = qdisc_dequeue_head(sch);
+        sch->bstats.bytes -= qdisc_pkt_len(skb_head);
+        sch->bstats.packets--;
+        sch->qstats.drops++;
+        kfree_skb(skb_head);
+
+        qdisc_enqueue_tail(skb, sch);
+
+        return NET_XMIT_CN;
+}
+
 static int fifo_init(struct Qdisc *sch, struct nlattr *opt)
 {
         struct fifo_sched_data *q = qdisc_priv(sch);
@@ -108,6 +129,20 @@ struct Qdisc_ops bfifo_qdisc_ops __read_mostly = {
 };
 EXPORT_SYMBOL(bfifo_qdisc_ops);
 
+struct Qdisc_ops pfifo_head_drop_qdisc_ops __read_mostly = {
+        .id             =       "pfifo_head_drop",
+        .priv_size      =       sizeof(struct fifo_sched_data),
+        .enqueue        =       pfifo_tail_enqueue,
+        .dequeue        =       qdisc_dequeue_head,
+        .peek           =       qdisc_peek_head,
+        .drop           =       qdisc_queue_drop_head,
+        .init           =       fifo_init,
+        .reset          =       qdisc_reset_queue,
+        .change         =       fifo_init,
+        .dump           =       fifo_dump,
+        .owner          =       THIS_MODULE,
+};
+
 /* Pass size change message down to embedded FIFO */
 int fifo_set_limit(struct Qdisc *q, unsigned int limit)
 {