Commit 19119f29 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: take care of compressed acks in tcp_add_reno_sack() 



Neal pointed out that non sack flows might suffer from ACK compression
added in the following patch ("tcp: implement coalescing on backlog queue")

Instead of tweaking tcp_add_backlog() we can take into
account how many ACK were coalesced, this information
will be available in skb_shinfo(skb)->gso_segs

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ebeef4bc

net/ipv4/tcp_input.c

+33 −25
Original line number Diff line number Diff line
@@ -1865,17 +1865,21 @@ static void tcp_check_reno_reordering(struct sock *sk, const int addend) 


/* Emulate SACKs for SACKless connection: account for a new dupack. */



static void tcp_add_reno_sack(struct sock *sk)

static void tcp_add_reno_sack(struct sock *sk, int num_dupack)

{

	if (num_dupack) {

		struct tcp_sock *tp = tcp_sk(sk);

		u32 prior_sacked = tp->sacked_out;

		s32 delivered;



	tp->sacked_out++;

		tp->sacked_out += num_dupack;

		tcp_check_reno_reordering(sk, 0);

	if (tp->sacked_out > prior_sacked)

		tp->delivered++; /* Some out-of-order packet is delivered */

		delivered = tp->sacked_out - prior_sacked;

		if (delivered > 0)

			tp->delivered += delivered;

		tcp_verify_left_out(tp);

	}

}



/* Account for ACK, ACKing some data in Reno Recovery phase. */
@@ -2636,7 +2640,7 @@ void tcp_enter_recovery(struct sock *sk, bool ece_ack) 
/* Process an ACK in CA_Loss state. Move to CA_Open if lost data are

 * recovered or spurious. Otherwise retransmits more on partial ACKs.

 */

static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack,

static void tcp_process_loss(struct sock *sk, int flag, int num_dupack,

			     int *rexmit)

{

	struct tcp_sock *tp = tcp_sk(sk);
@@ -2655,7 +2659,7 @@ static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack, 
			return;



		if (after(tp->snd_nxt, tp->high_seq)) {

			if (flag & FLAG_DATA_SACKED || is_dupack)

			if (flag & FLAG_DATA_SACKED || num_dupack)

				tp->frto = 0; /* Step 3.a. loss was real */

		} else if (flag & FLAG_SND_UNA_ADVANCED && !recovered) {

			tp->high_seq = tp->snd_nxt;
@@ -2681,8 +2685,8 @@ static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack, 
		/* A Reno DUPACK means new data in F-RTO step 2.b above are

		 * delivered. Lower inflight to clock out (re)tranmissions.

		 */

		if (after(tp->snd_nxt, tp->high_seq) && is_dupack)

			tcp_add_reno_sack(sk);

		if (after(tp->snd_nxt, tp->high_seq) && num_dupack)

			tcp_add_reno_sack(sk, num_dupack);

		else if (flag & FLAG_SND_UNA_ADVANCED)

			tcp_reset_reno_sack(tp);

	}
@@ -2759,12 +2763,12 @@ static bool tcp_force_fast_retransmit(struct sock *sk) 
 * tcp_xmit_retransmit_queue().

 */

static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una,

				  bool is_dupack, int *ack_flag, int *rexmit)

				  int num_dupack, int *ack_flag, int *rexmit)

{

	struct inet_connection_sock *icsk = inet_csk(sk);

	struct tcp_sock *tp = tcp_sk(sk);

	int fast_rexmit = 0, flag = *ack_flag;

	bool do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&

	bool do_lost = num_dupack || ((flag & FLAG_DATA_SACKED) &&

				      tcp_force_fast_retransmit(sk));



	if (!tp->packets_out && tp->sacked_out)
@@ -2812,8 +2816,8 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una, 
	switch (icsk->icsk_ca_state) {

	case TCP_CA_Recovery:

		if (!(flag & FLAG_SND_UNA_ADVANCED)) {

			if (tcp_is_reno(tp) && is_dupack)

				tcp_add_reno_sack(sk);

			if (tcp_is_reno(tp))

				tcp_add_reno_sack(sk, num_dupack);

		} else {

			if (tcp_try_undo_partial(sk, prior_snd_una))

				return;
@@ -2828,7 +2832,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una, 
		tcp_identify_packet_loss(sk, ack_flag);

		break;

	case TCP_CA_Loss:

		tcp_process_loss(sk, flag, is_dupack, rexmit);

		tcp_process_loss(sk, flag, num_dupack, rexmit);

		tcp_identify_packet_loss(sk, ack_flag);

		if (!(icsk->icsk_ca_state == TCP_CA_Open ||

		      (*ack_flag & FLAG_LOST_RETRANS)))
@@ -2839,8 +2843,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una, 
		if (tcp_is_reno(tp)) {

			if (flag & FLAG_SND_UNA_ADVANCED)

				tcp_reset_reno_sack(tp);

			if (is_dupack)

				tcp_add_reno_sack(sk);

			tcp_add_reno_sack(sk, num_dupack);

		}



		if (icsk->icsk_ca_state <= TCP_CA_Disorder)
@@ -3562,7 +3565,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) 
	bool is_sack_reneg = tp->is_sack_reneg;

	u32 ack_seq = TCP_SKB_CB(skb)->seq;

	u32 ack = TCP_SKB_CB(skb)->ack_seq;

	bool is_dupack = false;

	int num_dupack = 0;

	int prior_packets = tp->packets_out;

	u32 delivered = tp->delivered;

	u32 lost = tp->lost;
@@ -3673,8 +3676,13 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) 
		tcp_set_xmit_timer(sk);



	if (tcp_ack_is_dubious(sk, flag)) {

		is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));

		tcp_fastretrans_alert(sk, prior_snd_una, is_dupack, &flag,

		if (!(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP))) {

			num_dupack = 1;

			/* Consider if pure acks were aggregated in tcp_add_backlog() */

			if (!(flag & FLAG_DATA))

				num_dupack = max_t(u16, 1, skb_shinfo(skb)->gso_segs);

		}

		tcp_fastretrans_alert(sk, prior_snd_una, num_dupack, &flag,

				      &rexmit);

	}
@@ -3692,7 +3700,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) 
no_queue:

	/* If data was DSACKed, see if we can undo a cwnd reduction. */

	if (flag & FLAG_DSACKING_ACK) {

		tcp_fastretrans_alert(sk, prior_snd_una, is_dupack, &flag,

		tcp_fastretrans_alert(sk, prior_snd_una, num_dupack, &flag,

				      &rexmit);

		tcp_newly_delivered(sk, delivered, flag);

	}
@@ -3717,7 +3725,7 @@ old_ack: 
	if (TCP_SKB_CB(skb)->sacked) {

		flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una,

						&sack_state);

		tcp_fastretrans_alert(sk, prior_snd_una, is_dupack, &flag,

		tcp_fastretrans_alert(sk, prior_snd_una, num_dupack, &flag,

				      &rexmit);

		tcp_newly_delivered(sk, delivered, flag);

		tcp_xmit_recovery(sk, rexmit);

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