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Diffstat (limited to 'net/ipv4/tcp_output.c')
-rw-r--r--net/ipv4/tcp_output.c120
1 files changed, 82 insertions, 38 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index ce1d7cfbecfc..8327e5e86d15 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -434,6 +434,33 @@ static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb)
}
}
+/* Does SKB fit into the send window? */
+static inline int tcp_snd_wnd_test(struct tcp_sock *tp, struct sk_buff *skb, unsigned int cur_mss)
+{
+ u32 end_seq = TCP_SKB_CB(skb)->end_seq;
+
+ return !after(end_seq, tp->snd_una + tp->snd_wnd);
+}
+
+/* Can at least one segment of SKB be sent right now, according to the
+ * congestion window rules? If so, return how many segments are allowed.
+ */
+static inline unsigned int tcp_cwnd_test(struct tcp_sock *tp, struct sk_buff *skb)
+{
+ u32 in_flight, cwnd;
+
+ /* Don't be strict about the congestion window for the final FIN. */
+ if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)
+ return 1;
+
+ in_flight = tcp_packets_in_flight(tp);
+ cwnd = tp->snd_cwnd;
+ if (in_flight < cwnd)
+ return (cwnd - in_flight);
+
+ return 0;
+}
+
static inline int tcp_minshall_check(const struct tcp_sock *tp)
{
return after(tp->snd_sml,tp->snd_una) &&
@@ -442,7 +469,7 @@ static inline int tcp_minshall_check(const struct tcp_sock *tp)
/* Return 0, if packet can be sent now without violation Nagle's rules:
* 1. It is full sized.
- * 2. Or it contains FIN.
+ * 2. Or it contains FIN. (already checked by caller)
* 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.
@@ -453,56 +480,73 @@ static inline int tcp_nagle_check(const struct tcp_sock *tp,
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.
+/* Return non-zero if the Nagle test allows this packet to be
+ * sent now.
*/
-static int tcp_snd_test(struct sock *sk, struct sk_buff *skb,
- unsigned cur_mss, int nonagle)
+static inline int tcp_nagle_test(struct tcp_sock *tp, struct sk_buff *skb,
+ unsigned int cur_mss, int nonagle)
{
- struct tcp_sock *tp = tcp_sk(sk);
- int pkts = tcp_skb_pcount(skb);
+ /* Nagle rule does not apply to frames, which sit in the middle of the
+ * write_queue (they have no chances to get new data).
+ *
+ * This is implemented in the callers, where they modify the 'nonagle'
+ * argument based upon the location of SKB in the send queue.
+ */
+ if (nonagle & TCP_NAGLE_PUSH)
+ return 1;
+
+ /* Don't use the nagle rule for urgent data (or for the final FIN). */
+ if (tp->urg_mode ||
+ (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN))
+ return 1;
+
+ if (!tcp_nagle_check(tp, skb, cur_mss, nonagle))
+ return 1;
- if (!pkts) {
+ return 0;
+}
+
+/* This must be invoked the first time we consider transmitting
+ * SKB onto the wire.
+ */
+static inline int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb)
+{
+ int tso_segs = tcp_skb_pcount(skb);
+
+ if (!tso_segs) {
tcp_set_skb_tso_segs(sk, skb);
- pkts = tcp_skb_pcount(skb);
+ tso_segs = tcp_skb_pcount(skb);
}
+ return tso_segs;
+}
- /* 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).
- */
+/* This checks if the data bearing packet SKB (usually sk->sk_send_head)
+ * should be put on the wire right now. If so, it returns the number of
+ * packets allowed by the congestion window.
+ */
+static unsigned int tcp_snd_test(struct sock *sk, struct sk_buff *skb,
+ unsigned int cur_mss, int nonagle)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ unsigned int cwnd_quota;
- /* 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));
+ tcp_init_tso_segs(sk, skb);
+
+ if (!tcp_nagle_test(tp, skb, cur_mss, nonagle))
+ return 0;
+
+ cwnd_quota = tcp_cwnd_test(tp, skb);
+ if (cwnd_quota &&
+ !tcp_snd_wnd_test(tp, skb, cur_mss))
+ cwnd_quota = 0;
+
+ return cwnd_quota;
}
static inline int tcp_skb_is_last(const struct sock *sk,