[PATCH net-next 9/9] net_sched: sch_fq: remove dead code dealing with retransmits

[Eric Dumazet]

With the earliest departure time model, we no longer plan
special casing TCP retransmits. We therefore remove dead
code (since most compilers understood skb_is_retransmit()
was false)

Signed-off-by: Eric Dumazet <eduma...@google.com>
---
 net/sched/sch_fq.c | 58 ++++------------------------------------------
 1 file changed, 5 insertions(+), 53 deletions(-)

diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 
77692ad6741de14025bd848741604e775742430b..628a2cdcfc6f2fa69d9402f06881949d2e1423d9
 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -106,7 +106,6 @@ struct fq_sched_data {
 
        u64             stat_gc_flows;
        u64             stat_internal_packets;
-       u64             stat_tcp_retrans;
        u64             stat_throttled;
        u64             stat_flows_plimit;
        u64             stat_pkts_too_long;
@@ -327,62 +326,17 @@ static struct sk_buff *fq_dequeue_head(struct Qdisc *sch, 
struct fq_flow *flow)
        return skb;
 }
 
-/* We might add in the future detection of retransmits
- * For the time being, just return false
- */
-static bool skb_is_retransmit(struct sk_buff *skb)
-{
-       return false;
-}
-
-/* add skb to flow queue
- * flow queue is a linked list, kind of FIFO, except for TCP retransmits
- * We special case tcp retransmits to be transmitted before other packets.
- * We rely on fact that TCP retransmits are unlikely, so we do not waste
- * a separate queue or a pointer.
- * head->  [retrans pkt 1]
- *         [retrans pkt 2]
- *         [ normal pkt 1]
- *         [ normal pkt 2]
- *         [ normal pkt 3]
- * tail->  [ normal pkt 4]
- */
 static void flow_queue_add(struct fq_flow *flow, struct sk_buff *skb)
 {
-       struct sk_buff *prev, *head = flow->head;
+       struct sk_buff *head = flow->head;
 
        skb->next = NULL;
-       if (!head) {
+       if (!head)
                flow->head = skb;
-               flow->tail = skb;
-               return;
-       }
-       if (likely(!skb_is_retransmit(skb))) {
+       else
                flow->tail->next = skb;
-               flow->tail = skb;
-               return;
-       }
 
-       /* This skb is a tcp retransmit,
-        * find the last retrans packet in the queue
-        */
-       prev = NULL;
-       while (skb_is_retransmit(head)) {
-               prev = head;
-               head = head->next;
-               if (!head)
-                       break;
-       }
-       if (!prev) { /* no rtx packet in queue, become the new head */
-               skb->next = flow->head;
-               flow->head = skb;
-       } else {
-               if (prev == flow->tail)
-                       flow->tail = skb;
-               else
-                       skb->next = prev->next;
-               prev->next = skb;
-       }
+       flow->tail = skb;
 }
 
 static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
@@ -401,8 +355,6 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc 
*sch,
        }
 
        f->qlen++;
-       if (skb_is_retransmit(skb))
-               q->stat_tcp_retrans++;
        qdisc_qstats_backlog_inc(sch, skb);
        if (fq_flow_is_detached(f)) {
                struct sock *sk = skb->sk;
@@ -874,7 +826,7 @@ static int fq_dump_stats(struct Qdisc *sch, struct 
gnet_dump *d)
 
        st.gc_flows               = q->stat_gc_flows;
        st.highprio_packets       = q->stat_internal_packets;
-       st.tcp_retrans            = q->stat_tcp_retrans;
+       st.tcp_retrans            = 0;
        st.throttled              = q->stat_throttled;
        st.flows_plimit           = q->stat_flows_plimit;
        st.pkts_too_long          = q->stat_pkts_too_long;
-- 
2.19.0.444.g18242da7ef-goog