1 files changed, 43 insertions, 11 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 149ceb5c94ff..3f7bd7ae7d7a 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -100,6 +100,7 @@ int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
 #define FLAG_UPDATE_TS_RECENT	0x4000 /* tcp_replace_ts_recent() */
 #define FLAG_NO_CHALLENGE_ACK	0x8000 /* do not call tcp_send_challenge_ack()	*/
 #define FLAG_ACK_MAYBE_DELAYED	0x10000 /* Likely a delayed ACK */
+#define FLAG_DSACK_TLP		0x20000 /* DSACK for tail loss probe */
 
 #define FLAG_ACKED		(FLAG_DATA_ACKED|FLAG_SYN_ACKED)
 #define FLAG_NOT_DUP		(FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED)
@@ -454,11 +455,12 @@ static void tcp_sndbuf_expand(struct sock *sk)
  */
 
 /* Slow part of check#2. */
-static int __tcp_grow_window(const struct sock *sk, const struct sk_buff *skb)
+static int __tcp_grow_window(const struct sock *sk, const struct sk_buff *skb,
+			     unsigned int skbtruesize)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	/* Optimize this! */
-	int truesize = tcp_win_from_space(sk, skb->truesize) >> 1;
+	int truesize = tcp_win_from_space(sk, skbtruesize) >> 1;
 	int window = tcp_win_from_space(sk, sock_net(sk)->ipv4.sysctl_tcp_rmem[2]) >> 1;
 
 	while (tp->rcv_ssthresh <= window) {
@@ -471,7 +473,27 @@ static int __tcp_grow_window(const struct sock *sk, const struct sk_buff *skb)
 	return 0;
 }
 
-static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb)
+/* Even if skb appears to have a bad len/truesize ratio, TCP coalescing
+ * can play nice with us, as sk_buff and skb->head might be either
+ * freed or shared with up to MAX_SKB_FRAGS segments.
+ * Only give a boost to drivers using page frag(s) to hold the frame(s),
+ * and if no payload was pulled in skb->head before reaching us.
+ */
+static u32 truesize_adjust(bool adjust, const struct sk_buff *skb)
+{
+	u32 truesize = skb->truesize;
+
+	if (adjust && !skb_headlen(skb)) {
+		truesize -= SKB_TRUESIZE(skb_end_offset(skb));
+		/* paranoid check, some drivers might be buggy */
+		if (unlikely((int)truesize < (int)skb->len))
+			truesize = skb->truesize;
+	}
+	return truesize;
+}
+
+static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb,
+			    bool adjust)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	int room;
@@ -480,15 +502,16 @@ static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb)
 
 	/* Check #1 */
 	if (room > 0 && !tcp_under_memory_pressure(sk)) {
+		unsigned int truesize = truesize_adjust(adjust, skb);
 		int incr;
 
 		/* Check #2. Increase window, if skb with such overhead
 		 * will fit to rcvbuf in future.
 		 */
-		if (tcp_win_from_space(sk, skb->truesize) <= skb->len)
+		if (tcp_win_from_space(sk, truesize) <= skb->len)
 			incr = 2 * tp->advmss;
 		else
-			incr = __tcp_grow_window(sk, skb);
+			incr = __tcp_grow_window(sk, skb, truesize);
 
 		if (incr) {
 			incr = max_t(int, incr, 2 * skb->len);
@@ -782,7 +805,7 @@ static void tcp_event_data_recv(struct sock *sk, struct sk_buff *skb)
 	tcp_ecn_check_ce(sk, skb);
 
 	if (skb->len >= 128)
-		tcp_grow_window(sk, skb);
+		tcp_grow_window(sk, skb, true);
 }
 
 /* Called to compute a smoothed rtt estimate. The data fed to this
@@ -969,6 +992,8 @@ static u32 tcp_dsack_seen(struct tcp_sock *tp, u32 start_seq,
 		return 0;
 	if (seq_len > tp->mss_cache)
 		dup_segs = DIV_ROUND_UP(seq_len, tp->mss_cache);
+	else if (tp->tlp_high_seq && tp->tlp_high_seq == end_seq)
+		state->flag |= FLAG_DSACK_TLP;
 
 	tp->dsack_dups += dup_segs;
 	/* Skip the DSACK if dup segs weren't retransmitted by sender */
@@ -976,7 +1001,14 @@ static u32 tcp_dsack_seen(struct tcp_sock *tp, u32 start_seq,
 		return 0;
 
 	tp->rx_opt.sack_ok |= TCP_DSACK_SEEN;
-	tp->rack.dsack_seen = 1;
+	/* We increase the RACK ordering window in rounds where we receive
+	 * DSACKs that may have been due to reordering causing RACK to trigger
+	 * a spurious fast recovery. Thus RACK ignores DSACKs that happen
+	 * without having seen reordering, or that match TLP probes (TLP
+	 * is timer-driven, not triggered by RACK).
+	 */
+	if (tp->reord_seen && !(state->flag & FLAG_DSACK_TLP))
+		tp->rack.dsack_seen = 1;
 
 	state->flag |= FLAG_DSACKING_ACK;
 	/* A spurious retransmission is delivered */
@@ -3628,7 +3660,7 @@ static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
 	if (!tp->tlp_retrans) {
 		/* TLP of new data has been acknowledged */
 		tp->tlp_high_seq = 0;
-	} else if (flag & FLAG_DSACKING_ACK) {
+	} else if (flag & FLAG_DSACK_TLP) {
 		/* This DSACK means original and TLP probe arrived; no loss */
 		tp->tlp_high_seq = 0;
 	} else if (after(ack, tp->tlp_high_seq)) {
@@ -4769,7 +4801,7 @@ coalesce_done:
 		 * and trigger fast retransmit.
 		 */
 		if (tcp_is_sack(tp))
-			tcp_grow_window(sk, skb);
+			tcp_grow_window(sk, skb, true);
 		kfree_skb_partial(skb, fragstolen);
 		skb = NULL;
 		goto add_sack;
@@ -4857,7 +4889,7 @@ end:
 		 * and trigger fast retransmit.
 		 */
 		if (tcp_is_sack(tp))
-			tcp_grow_window(sk, skb);
+			tcp_grow_window(sk, skb, false);
 		skb_condense(skb);
 		skb_set_owner_r(skb, sk);
 	}
@@ -5383,7 +5415,7 @@ static void tcp_new_space(struct sock *sk)
 		tp->snd_cwnd_stamp = tcp_jiffies32;
 	}
 
-	sk->sk_write_space(sk);
+	INDIRECT_CALL_1(sk->sk_write_space, sk_stream_write_space, sk);
 }
 
 static void tcp_check_space(struct sock *sk)