tcp: Revert "tcp: remove CA_ACK_SLOWPATH"

This change was a followup to the header prediction removal,
so first revert this as a prerequisite to back out hp removal.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/tcp.h b/include/net/tcp.h
index c614ff135b6619744d61a8d6f1c14a99a7e96afd..c546d13ffbca857c80443403551fe92b5f1cf23c 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -910,8 +910,9 @@ enum tcp_ca_event {
 
 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
 enum tcp_ca_ack_event_flags {
-       CA_ACK_WIN_UPDATE       = (1 << 0),     /* ACK updated window */
-       CA_ACK_ECE              = (1 << 1),     /* ECE bit is set on ack */
+       CA_ACK_SLOWPATH         = (1 << 0),     /* In slow path processing */
+       CA_ACK_WIN_UPDATE       = (1 << 1),     /* ACK updated window */
+       CA_ACK_ECE              = (1 << 2),     /* ECE bit is set on ack */
 };
 
 /*

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 7616cd76f6f6a62f395da897baef2c66c0098193..a0e436366d31707922e21c495bec7d8312d643d2 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3552,7 +3552,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
        u32 lost = tp->lost;
        int acked = 0; /* Number of packets newly acked */
        int rexmit = REXMIT_NONE; /* Flag to (re)transmit to recover losses */
-       u32 ack_ev_flags = 0;
 
        sack_state.first_sackt = 0;
        sack_state.rate = &rs;
@@ -3593,26 +3592,30 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
        if (flag & FLAG_UPDATE_TS_RECENT)
                tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
 
-       if (ack_seq != TCP_SKB_CB(skb)->end_seq)
-               flag |= FLAG_DATA;
-       else
-               NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPPUREACKS);
+       {
+               u32 ack_ev_flags = CA_ACK_SLOWPATH;
 
-       flag |= tcp_ack_update_window(sk, skb, ack, ack_seq);
+               if (ack_seq != TCP_SKB_CB(skb)->end_seq)
+                       flag |= FLAG_DATA;
+               else
+                       NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPPUREACKS);
 
-       if (TCP_SKB_CB(skb)->sacked)
-               flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una,
-                                               &sack_state);
+               flag |= tcp_ack_update_window(sk, skb, ack, ack_seq);
 
-       if (tcp_ecn_rcv_ecn_echo(tp, tcp_hdr(skb))) {
-               flag |= FLAG_ECE;
-               ack_ev_flags = CA_ACK_ECE;
-       }
+               if (TCP_SKB_CB(skb)->sacked)
+                       flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una,
+                                                       &sack_state);
+
+               if (tcp_ecn_rcv_ecn_echo(tp, tcp_hdr(skb))) {
+                       flag |= FLAG_ECE;
+                       ack_ev_flags |= CA_ACK_ECE;
+               }
 
-       if (flag & FLAG_WIN_UPDATE)
-               ack_ev_flags |= CA_ACK_WIN_UPDATE;
+               if (flag & FLAG_WIN_UPDATE)
+                       ack_ev_flags |= CA_ACK_WIN_UPDATE;
 
-       tcp_in_ack_event(sk, ack_ev_flags);
+               tcp_in_ack_event(sk, ack_ev_flags);
+       }
 
        /* We passed data and got it acked, remove any soft error
         * log. Something worked...

diff --git a/net/ipv4/tcp_westwood.c b/net/ipv4/tcp_westwood.c
index e5de8431094960fe0cec2837ed356c6a66bba667..bec9cafbe3f92938e5d79d743d629b2f33464418 100644 (file)
--- a/net/ipv4/tcp_westwood.c
+++ b/net/ipv4/tcp_westwood.c
@@ -153,6 +153,24 @@ static inline void update_rtt_min(struct westwood *w)
                w->rtt_min = min(w->rtt, w->rtt_min);
 }
 
+/*
+ * @westwood_fast_bw
+ * It is called when we are in fast path. In particular it is called when
+ * header prediction is successful. In such case in fact update is
+ * straight forward and doesn't need any particular care.
+ */
+static inline void westwood_fast_bw(struct sock *sk)
+{
+       const struct tcp_sock *tp = tcp_sk(sk);
+       struct westwood *w = inet_csk_ca(sk);
+
+       westwood_update_window(sk);
+
+       w->bk += tp->snd_una - w->snd_una;
+       w->snd_una = tp->snd_una;
+       update_rtt_min(w);
+}
+
 /*
  * @westwood_acked_count
  * This function evaluates cumul_ack for evaluating bk in case of
@@ -205,12 +223,17 @@ static u32 tcp_westwood_bw_rttmin(const struct sock *sk)
 
 static void tcp_westwood_ack(struct sock *sk, u32 ack_flags)
 {
-       struct westwood *w = inet_csk_ca(sk);
+       if (ack_flags & CA_ACK_SLOWPATH) {
+               struct westwood *w = inet_csk_ca(sk);
 
-       westwood_update_window(sk);
-       w->bk += westwood_acked_count(sk);
+               westwood_update_window(sk);
+               w->bk += westwood_acked_count(sk);
 
-       update_rtt_min(w);
+               update_rtt_min(w);
+               return;
+       }
+
+       westwood_fast_bw(sk);
 }
 
 static void tcp_westwood_event(struct sock *sk, enum tcp_ca_event event)