tcp: kill eff_sacks "cache", the sole user can calculate itself

Also fixes insignificant bug that would cause sending of stale
SACK block (would occur in some corner cases).

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 9 insertions, 21 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 03f5ede87224..e4442a293eb0 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4099,7 +4099,6 @@ static void tcp_dsack_set(struct sock *sk, u32 seq, u32 end_seq)
                 tp->rx_opt.dsack = 1;
                 tp->duplicate_sack[0].start_seq = seq;
                 tp->duplicate_sack[0].end_seq = end_seq;
-                tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks + 1;
         }
 }
 
@@ -4154,8 +4153,6 @@ static void tcp_sack_maybe_coalesce(struct tcp_sock *tp)
                          * Decrease num_sacks.
                          */
                         tp->rx_opt.num_sacks--;
-                        tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks +
-                                               tp->rx_opt.dsack;
                         for (i = this_sack; i < tp->rx_opt.num_sacks; i++)
                                 sp[i] = sp[i + 1];
                         continue;
@@ -4218,7 +4215,6 @@ new_sack:
         sp->start_seq = seq;
         sp->end_seq = end_seq;
         tp->rx_opt.num_sacks++;
-        tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack;
 }
 
 /* RCV.NXT advances, some SACKs should be eaten. */
@@ -4232,7 +4228,6 @@ static void tcp_sack_remove(struct tcp_sock *tp)
         /* Empty ofo queue, hence, all the SACKs are eaten. Clear. */
         if (skb_queue_empty(&tp->out_of_order_queue)) {
                 tp->rx_opt.num_sacks = 0;
-                tp->rx_opt.eff_sacks = tp->rx_opt.dsack;
                 return;
         }
 
@@ -4253,11 +4248,8 @@ static void tcp_sack_remove(struct tcp_sock *tp)
                 this_sack++;
                 sp++;
         }
-        if (num_sacks != tp->rx_opt.num_sacks) {
+        if (num_sacks != tp->rx_opt.num_sacks)
                 tp->rx_opt.num_sacks = num_sacks;
-                tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks +
-                                       tp->rx_opt.dsack;
-        }
 }
 
 /* This one checks to see if we can put data from the
@@ -4333,10 +4325,8 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
 
         TCP_ECN_accept_cwr(tp, skb);
 
-        if (tp->rx_opt.dsack) {
+        if (tp->rx_opt.dsack)
                 tp->rx_opt.dsack = 0;
-                tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks;
-        }
 
         /*  Queue data for delivery to the user.
          *  Packets in sequence go to the receive queue.
@@ -4456,7 +4446,6 @@ drop:
                 if (tcp_is_sack(tp)) {
                         tp->rx_opt.num_sacks = 1;
                         tp->rx_opt.dsack     = 0;
-                        tp->rx_opt.eff_sacks = 1;
                         tp->selective_acks[0].start_seq = TCP_SKB_CB(skb)->seq;
                         tp->selective_acks[0].end_seq =
                                                 TCP_SKB_CB(skb)->end_seq;
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index f67effbb102b..bb3d8b35f19a 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -434,9 +434,8 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
                 newtp->rx_opt.saw_tstamp = 0;
 
                 newtp->rx_opt.dsack = 0;
-                newtp->rx_opt.eff_sacks = 0;
-
                 newtp->rx_opt.num_sacks = 0;
+
                 newtp->urg_data = 0;
 
                 if (sock_flag(newsk, SOCK_KEEPOPEN))
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 61445b57610c..1555bb73b638 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -441,10 +441,8 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
                         *ptr++ = htonl(sp[this_sack].end_seq);
                 }
 
-                if (tp->rx_opt.dsack) {
+                if (tp->rx_opt.dsack)
                         tp->rx_opt.dsack = 0;
-                        tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks;
-                }
         }
 }
 
@@ -550,6 +548,7 @@ static unsigned tcp_established_options(struct sock *sk, struct sk_buff *skb,
         struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL;
         struct tcp_sock *tp = tcp_sk(sk);
         unsigned size = 0;
+        unsigned int eff_sacks;
 
 #ifdef CONFIG_TCP_MD5SIG
         *md5 = tp->af_specific->md5_lookup(sk, sk);
@@ -568,10 +567,11 @@ static unsigned tcp_established_options(struct sock *sk, struct sk_buff *skb,
                 size += TCPOLEN_TSTAMP_ALIGNED;
         }
 
-        if (unlikely(tp->rx_opt.eff_sacks)) {
+        eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack;
+        if (unlikely(eff_sacks)) {
                 const unsigned remaining = MAX_TCP_OPTION_SPACE - size;
                 opts->num_sack_blocks =
-                        min_t(unsigned, tp->rx_opt.eff_sacks,
+                        min_t(unsigned, eff_sacks,
                               (remaining - TCPOLEN_SACK_BASE_ALIGNED) /
                               TCPOLEN_SACK_PERBLOCK);
                 size += TCPOLEN_SACK_BASE_ALIGNED +
@@ -1418,7 +1418,7 @@ static int tcp_mtu_probe(struct sock *sk)
             icsk->icsk_mtup.probe_size ||
             inet_csk(sk)->icsk_ca_state != TCP_CA_Open ||
             tp->snd_cwnd < 11 ||
-            tp->rx_opt.eff_sacks)
+            tp->rx_opt.num_sacks || tp->rx_opt.dsack)
                 return -1;
 
         /* Very simple search strategy: just double the MSS. */