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Diffstat (limited to 'net/ipv4/tcp_output.c')
-rw-r--r--net/ipv4/tcp_output.c150
1 files changed, 129 insertions, 21 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 389deeb2a45..2cbe879ee16 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -413,6 +413,135 @@ static inline void tcp_tso_set_push(struct sk_buff *skb)
TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
}
+static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ if (skb->len <= tp->mss_cache_std ||
+ !(sk->sk_route_caps & NETIF_F_TSO)) {
+ /* Avoid the costly divide in the normal
+ * non-TSO case.
+ */
+ skb_shinfo(skb)->tso_segs = 1;
+ skb_shinfo(skb)->tso_size = 0;
+ } else {
+ unsigned int factor;
+
+ factor = skb->len + (tp->mss_cache_std - 1);
+ factor /= tp->mss_cache_std;
+ skb_shinfo(skb)->tso_segs = factor;
+ skb_shinfo(skb)->tso_size = tp->mss_cache_std;
+ }
+}
+
+static inline int tcp_minshall_check(const struct tcp_sock *tp)
+{
+ return after(tp->snd_sml,tp->snd_una) &&
+ !after(tp->snd_sml, tp->snd_nxt);
+}
+
+/* Return 0, if packet can be sent now without violation Nagle's rules:
+ * 1. It is full sized.
+ * 2. Or it contains FIN.
+ * 3. Or TCP_NODELAY was set.
+ * 4. Or TCP_CORK is not set, and all sent packets are ACKed.
+ * With Minshall's modification: all sent small packets are ACKed.
+ */
+
+static inline int tcp_nagle_check(const struct tcp_sock *tp,
+ const struct sk_buff *skb,
+ unsigned mss_now, int nonagle)
+{
+ return (skb->len < mss_now &&
+ !(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) &&
+ ((nonagle&TCP_NAGLE_CORK) ||
+ (!nonagle &&
+ tp->packets_out &&
+ tcp_minshall_check(tp))));
+}
+
+/* This checks if the data bearing packet SKB (usually sk->sk_send_head)
+ * should be put on the wire right now.
+ */
+static int tcp_snd_test(struct sock *sk, struct sk_buff *skb,
+ unsigned cur_mss, int nonagle)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ int pkts = tcp_skb_pcount(skb);
+
+ if (!pkts) {
+ tcp_set_skb_tso_segs(sk, skb);
+ pkts = tcp_skb_pcount(skb);
+ }
+
+ /* RFC 1122 - section 4.2.3.4
+ *
+ * We must queue if
+ *
+ * a) The right edge of this frame exceeds the window
+ * b) There are packets in flight and we have a small segment
+ * [SWS avoidance and Nagle algorithm]
+ * (part of SWS is done on packetization)
+ * Minshall version sounds: there are no _small_
+ * segments in flight. (tcp_nagle_check)
+ * c) We have too many packets 'in flight'
+ *
+ * Don't use the nagle rule for urgent data (or
+ * for the final FIN -DaveM).
+ *
+ * Also, Nagle rule does not apply to frames, which
+ * sit in the middle of queue (they have no chances
+ * to get new data) and if room at tail of skb is
+ * not enough to save something seriously (<32 for now).
+ */
+
+ /* Don't be strict about the congestion window for the
+ * final FIN frame. -DaveM
+ */
+ return (((nonagle&TCP_NAGLE_PUSH) || tp->urg_mode
+ || !tcp_nagle_check(tp, skb, cur_mss, nonagle)) &&
+ (((tcp_packets_in_flight(tp) + (pkts-1)) < tp->snd_cwnd) ||
+ (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)) &&
+ !after(TCP_SKB_CB(skb)->end_seq, tp->snd_una + tp->snd_wnd));
+}
+
+static inline int tcp_skb_is_last(const struct sock *sk,
+ const struct sk_buff *skb)
+{
+ return skb->next == (struct sk_buff *)&sk->sk_write_queue;
+}
+
+/* Push out any pending frames which were held back due to
+ * TCP_CORK or attempt at coalescing tiny packets.
+ * The socket must be locked by the caller.
+ */
+void __tcp_push_pending_frames(struct sock *sk, struct tcp_sock *tp,
+ unsigned cur_mss, int nonagle)
+{
+ struct sk_buff *skb = sk->sk_send_head;
+
+ if (skb) {
+ if (!tcp_skb_is_last(sk, skb))
+ nonagle = TCP_NAGLE_PUSH;
+ if (!tcp_snd_test(sk, skb, cur_mss, nonagle) ||
+ tcp_write_xmit(sk, nonagle))
+ tcp_check_probe_timer(sk, tp);
+ }
+ tcp_cwnd_validate(sk, tp);
+}
+
+int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp)
+{
+ struct sk_buff *skb = sk->sk_send_head;
+
+ return (skb &&
+ tcp_snd_test(sk, skb, tcp_current_mss(sk, 1),
+ (tcp_skb_is_last(sk, skb) ?
+ TCP_NAGLE_PUSH :
+ tp->nonagle)));
+}
+
+
/* Send _single_ skb sitting at the send head. This function requires
* true push pending frames to setup probe timer etc.
*/
@@ -434,27 +563,6 @@ void tcp_push_one(struct sock *sk, unsigned cur_mss)
}
}
-void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb)
-{
- struct tcp_sock *tp = tcp_sk(sk);
-
- if (skb->len <= tp->mss_cache_std ||
- !(sk->sk_route_caps & NETIF_F_TSO)) {
- /* Avoid the costly divide in the normal
- * non-TSO case.
- */
- skb_shinfo(skb)->tso_segs = 1;
- skb_shinfo(skb)->tso_size = 0;
- } else {
- unsigned int factor;
-
- factor = skb->len + (tp->mss_cache_std - 1);
- factor /= tp->mss_cache_std;
- skb_shinfo(skb)->tso_segs = factor;
- skb_shinfo(skb)->tso_size = tp->mss_cache_std;
- }
-}
-
/* Function to create two new TCP segments. Shrinks the given segment
* to the specified size and appends a new segment with the rest of the
* packet to the list. This won't be called frequently, I hope.