1 files changed, 31 insertions, 278 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 53de1424c13c..d73903fe8c83 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -103,7 +103,6 @@ int sysctl_tcp_invalid_ratelimit __read_mostly = HZ/2;
 #define FLAG_DATA_SACKED	0x20 /* New SACK.				*/
 #define FLAG_ECE		0x40 /* ECE in this ACK				*/
 #define FLAG_LOST_RETRANS	0x80 /* This ACK marks some retransmission lost */
-#define FLAG_SLOWPATH		0x100 /* Do not skip RFC checks for window update.*/
 #define FLAG_ORIG_SACK_ACKED	0x200 /* Never retransmitted data are (s)acked	*/
 #define FLAG_SND_UNA_ADVANCED	0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */
 #define FLAG_DSACKING_ACK	0x800 /* SACK blocks contained D-SACK info */
@@ -1952,6 +1951,7 @@ void tcp_enter_loss(struct sock *sk)
 	    !after(tp->high_seq, tp->snd_una) ||
 	    (icsk->icsk_ca_state == TCP_CA_Loss && !icsk->icsk_retransmits)) {
 		tp->prior_ssthresh = tcp_current_ssthresh(sk);
+		tp->prior_cwnd = tp->snd_cwnd;
 		tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
 		tcp_ca_event(sk, CA_EVENT_LOSS);
 		tcp_init_undo(tp);
@@ -3372,12 +3372,6 @@ static int tcp_ack_update_window(struct sock *sk, const struct sk_buff *skb, u32
 		if (tp->snd_wnd != nwin) {
 			tp->snd_wnd = nwin;
 
-			/* Note, it is the only place, where
-			 * fast path is recovered for sending TCP.
-			 */
-			tp->pred_flags = 0;
-			tcp_fast_path_check(sk);
-
 			if (tcp_send_head(sk))
 				tcp_slow_start_after_idle_check(sk);
 
@@ -3559,6 +3553,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	u32 lost = tp->lost;
 	int acked = 0; /* Number of packets newly acked */
 	int rexmit = REXMIT_NONE; /* Flag to (re)transmit to recover losses */
+	u32 ack_ev_flags = 0;
 
 	sack_state.first_sackt = 0;
 	sack_state.rate = &rs;
@@ -3599,42 +3594,26 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	if (flag & FLAG_UPDATE_TS_RECENT)
 		tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
 
-	if (!(flag & FLAG_SLOWPATH) && after(ack, prior_snd_una)) {
-		/* Window is constant, pure forward advance.
-		 * No more checks are required.
-		 * Note, we use the fact that SND.UNA>=SND.WL2.
-		 */
-		tcp_update_wl(tp, ack_seq);
-		tcp_snd_una_update(tp, ack);
-		flag |= FLAG_WIN_UPDATE;
-
-		tcp_in_ack_event(sk, CA_ACK_WIN_UPDATE);
-
-		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPHPACKS);
-	} else {
-		u32 ack_ev_flags = CA_ACK_SLOWPATH;
-
-		if (ack_seq != TCP_SKB_CB(skb)->end_seq)
-			flag |= FLAG_DATA;
-		else
-			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPPUREACKS);
+	if (ack_seq != TCP_SKB_CB(skb)->end_seq)
+		flag |= FLAG_DATA;
+	else
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPPUREACKS);
 
-		flag |= tcp_ack_update_window(sk, skb, ack, ack_seq);
+	flag |= tcp_ack_update_window(sk, skb, ack, ack_seq);
 
-		if (TCP_SKB_CB(skb)->sacked)
-			flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una,
-							&sack_state);
+	if (TCP_SKB_CB(skb)->sacked)
+		flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una,
+						&sack_state);
 
-		if (tcp_ecn_rcv_ecn_echo(tp, tcp_hdr(skb))) {
-			flag |= FLAG_ECE;
-			ack_ev_flags |= CA_ACK_ECE;
-		}
+	if (tcp_ecn_rcv_ecn_echo(tp, tcp_hdr(skb))) {
+		flag |= FLAG_ECE;
+		ack_ev_flags = CA_ACK_ECE;
+	}
 
-		if (flag & FLAG_WIN_UPDATE)
-			ack_ev_flags |= CA_ACK_WIN_UPDATE;
+	if (flag & FLAG_WIN_UPDATE)
+		ack_ev_flags |= CA_ACK_WIN_UPDATE;
 
-		tcp_in_ack_event(sk, ack_ev_flags);
-	}
+	tcp_in_ack_event(sk, ack_ev_flags);
 
 	/* We passed data and got it acked, remove any soft error
 	 * log. Something worked...
@@ -4402,8 +4381,6 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
 		return;
 	}
 
-	/* Disable header prediction. */
-	tp->pred_flags = 0;
 	inet_csk_schedule_ack(sk);
 
 	NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPOFOQUEUE);
@@ -4592,8 +4569,8 @@ err:
 static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
-	bool fragstolen = false;
-	int eaten = -1;
+	bool fragstolen;
+	int eaten;
 
 	if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
 		__kfree_skb(skb);
@@ -4615,32 +4592,13 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
 			goto out_of_window;
 
 		/* Ok. In sequence. In window. */
-		if (tp->ucopy.task == current &&
-		    tp->copied_seq == tp->rcv_nxt && tp->ucopy.len &&
-		    sock_owned_by_user(sk) && !tp->urg_data) {
-			int chunk = min_t(unsigned int, skb->len,
-					  tp->ucopy.len);
-
-			__set_current_state(TASK_RUNNING);
-
-			if (!skb_copy_datagram_msg(skb, 0, tp->ucopy.msg, chunk)) {
-				tp->ucopy.len -= chunk;
-				tp->copied_seq += chunk;
-				eaten = (chunk == skb->len);
-				tcp_rcv_space_adjust(sk);
-			}
-		}
-
-		if (eaten <= 0) {
 queue_and_out:
-			if (eaten < 0) {
-				if (skb_queue_len(&sk->sk_receive_queue) == 0)
-					sk_forced_mem_schedule(sk, skb->truesize);
-				else if (tcp_try_rmem_schedule(sk, skb, skb->truesize))
-					goto drop;
-			}
-			eaten = tcp_queue_rcv(sk, skb, 0, &fragstolen);
-		}
+		if (skb_queue_len(&sk->sk_receive_queue) == 0)
+			sk_forced_mem_schedule(sk, skb->truesize);
+		else if (tcp_try_rmem_schedule(sk, skb, skb->truesize))
+			goto drop;
+
+		eaten = tcp_queue_rcv(sk, skb, 0, &fragstolen);
 		tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq);
 		if (skb->len)
 			tcp_event_data_recv(sk, skb);
@@ -4660,8 +4618,6 @@ queue_and_out:
 		if (tp->rx_opt.num_sacks)
 			tcp_sack_remove(tp);
 
-		tcp_fast_path_check(sk);
-
 		if (eaten > 0)
 			kfree_skb_partial(skb, fragstolen);
 		if (!sock_flag(sk, SOCK_DEAD))
@@ -4987,7 +4943,6 @@ static int tcp_prune_queue(struct sock *sk)
 	NET_INC_STATS(sock_net(sk), LINUX_MIB_RCVPRUNED);
 
 	/* Massive buffer overcommit. */
-	tp->pred_flags = 0;
 	return -1;
 }
 
@@ -5159,9 +5114,6 @@ static void tcp_check_urg(struct sock *sk, const struct tcphdr *th)
 
 	tp->urg_data = TCP_URG_NOTYET;
 	tp->urg_seq = ptr;
-
-	/* Disable header prediction. */
-	tp->pred_flags = 0;
 }
 
 /* This is the 'fast' part of urgent handling. */
@@ -5190,26 +5142,6 @@ static void tcp_urg(struct sock *sk, struct sk_buff *skb, const struct tcphdr *t
 	}
 }
 
-static int tcp_copy_to_iovec(struct sock *sk, struct sk_buff *skb, int hlen)
-{
-	struct tcp_sock *tp = tcp_sk(sk);
-	int chunk = skb->len - hlen;
-	int err;
-
-	if (skb_csum_unnecessary(skb))
-		err = skb_copy_datagram_msg(skb, hlen, tp->ucopy.msg, chunk);
-	else
-		err = skb_copy_and_csum_datagram_msg(skb, hlen, tp->ucopy.msg);
-
-	if (!err) {
-		tp->ucopy.len -= chunk;
-		tp->copied_seq += chunk;
-		tcp_rcv_space_adjust(sk);
-	}
-
-	return err;
-}
-
 /* Accept RST for rcv_nxt - 1 after a FIN.
  * When tcp connections are abruptly terminated from Mac OSX (via ^C), a
  * FIN is sent followed by a RST packet. The RST is sent with the same
@@ -5340,201 +5272,29 @@ discard:
 
 /*
  *	TCP receive function for the ESTABLISHED state.
- *
- *	It is split into a fast path and a slow path. The fast path is
- * 	disabled when:
- *	- A zero window was announced from us - zero window probing
- *        is only handled properly in the slow path.
- *	- Out of order segments arrived.
- *	- Urgent data is expected.
- *	- There is no buffer space left
- *	- Unexpected TCP flags/window values/header lengths are received
- *	  (detected by checking the TCP header against pred_flags)
- *	- Data is sent in both directions. Fast path only supports pure senders
- *	  or pure receivers (this means either the sequence number or the ack
- *	  value must stay constant)
- *	- Unexpected TCP option.
- *
- *	When these conditions are not satisfied it drops into a standard
- *	receive procedure patterned after RFC793 to handle all cases.
- *	The first three cases are guaranteed by proper pred_flags setting,
- *	the rest is checked inline. Fast processing is turned on in
- *	tcp_data_queue when everything is OK.
  */
 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
-			 const struct tcphdr *th, unsigned int len)
+			 const struct tcphdr *th)
 {
+	unsigned int len = skb->len;
 	struct tcp_sock *tp = tcp_sk(sk);
 
 	tcp_mstamp_refresh(tp);
 	if (unlikely(!sk->sk_rx_dst))
 		inet_csk(sk)->icsk_af_ops->sk_rx_dst_set(sk, skb);
-	/*
-	 *	Header prediction.
-	 *	The code loosely follows the one in the famous
-	 *	"30 instruction TCP receive" Van Jacobson mail.
-	 *
-	 *	Van's trick is to deposit buffers into socket queue
-	 *	on a device interrupt, to call tcp_recv function
-	 *	on the receive process context and checksum and copy
-	 *	the buffer to user space. smart...
-	 *
-	 *	Our current scheme is not silly either but we take the
-	 *	extra cost of the net_bh soft interrupt processing...
-	 *	We do checksum and copy also but from device to kernel.
-	 */
 
 	tp->rx_opt.saw_tstamp = 0;
 
-	/*	pred_flags is 0xS?10 << 16 + snd_wnd
-	 *	if header_prediction is to be made
-	 *	'S' will always be tp->tcp_header_len >> 2
-	 *	'?' will be 0 for the fast path, otherwise pred_flags is 0 to
-	 *  turn it off	(when there are holes in the receive
-	 *	 space for instance)
-	 *	PSH flag is ignored.
-	 */
-
-	if ((tcp_flag_word(th) & TCP_HP_BITS) == tp->pred_flags &&
-	    TCP_SKB_CB(skb)->seq == tp->rcv_nxt &&
-	    !after(TCP_SKB_CB(skb)->ack_seq, tp->snd_nxt)) {
-		int tcp_header_len = tp->tcp_header_len;
-
-		/* Timestamp header prediction: tcp_header_len
-		 * is automatically equal to th->doff*4 due to pred_flags
-		 * match.
-		 */
-
-		/* Check timestamp */
-		if (tcp_header_len == sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) {
-			/* No? Slow path! */
-			if (!tcp_parse_aligned_timestamp(tp, th))
-				goto slow_path;
-
-			/* If PAWS failed, check it more carefully in slow path */
-			if ((s32)(tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent) < 0)
-				goto slow_path;
-
-			/* DO NOT update ts_recent here, if checksum fails
-			 * and timestamp was corrupted part, it will result
-			 * in a hung connection since we will drop all
-			 * future packets due to the PAWS test.
-			 */
-		}
-
-		if (len <= tcp_header_len) {
-			/* Bulk data transfer: sender */
-			if (len == tcp_header_len) {
-				/* Predicted packet is in window by definition.
-				 * seq == rcv_nxt and rcv_wup <= rcv_nxt.
-				 * Hence, check seq<=rcv_wup reduces to:
-				 */
-				if (tcp_header_len ==
-				    (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) &&
-				    tp->rcv_nxt == tp->rcv_wup)
-					tcp_store_ts_recent(tp);
-
-				/* We know that such packets are checksummed
-				 * on entry.
-				 */
-				tcp_ack(sk, skb, 0);
-				__kfree_skb(skb);
-				tcp_data_snd_check(sk);
-				return;
-			} else { /* Header too small */
-				TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);
-				goto discard;
-			}
-		} else {
-			int eaten = 0;
-			bool fragstolen = false;
-
-			if (tp->ucopy.task == current &&
-			    tp->copied_seq == tp->rcv_nxt &&
-			    len - tcp_header_len <= tp->ucopy.len &&
-			    sock_owned_by_user(sk)) {
-				__set_current_state(TASK_RUNNING);
-
-				if (!tcp_copy_to_iovec(sk, skb, tcp_header_len)) {
-					/* Predicted packet is in window by definition.
-					 * seq == rcv_nxt and rcv_wup <= rcv_nxt.
-					 * Hence, check seq<=rcv_wup reduces to:
-					 */
-					if (tcp_header_len ==
-					    (sizeof(struct tcphdr) +
-					     TCPOLEN_TSTAMP_ALIGNED) &&
-					    tp->rcv_nxt == tp->rcv_wup)
-						tcp_store_ts_recent(tp);
-
-					tcp_rcv_rtt_measure_ts(sk, skb);
-
-					__skb_pull(skb, tcp_header_len);
-					tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq);
-					NET_INC_STATS(sock_net(sk),
-							LINUX_MIB_TCPHPHITSTOUSER);
-					eaten = 1;
-				}
-			}
-			if (!eaten) {
-				if (tcp_checksum_complete(skb))
-					goto csum_error;
-
-				if ((int)skb->truesize > sk->sk_forward_alloc)
-					goto step5;
-
-				/* Predicted packet is in window by definition.
-				 * seq == rcv_nxt and rcv_wup <= rcv_nxt.
-				 * Hence, check seq<=rcv_wup reduces to:
-				 */
-				if (tcp_header_len ==
-				    (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) &&
-				    tp->rcv_nxt == tp->rcv_wup)
-					tcp_store_ts_recent(tp);
-
-				tcp_rcv_rtt_measure_ts(sk, skb);
-
-				NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPHPHITS);
-
-				/* Bulk data transfer: receiver */
-				eaten = tcp_queue_rcv(sk, skb, tcp_header_len,
-						      &fragstolen);
-			}
-
-			tcp_event_data_recv(sk, skb);
-
-			if (TCP_SKB_CB(skb)->ack_seq != tp->snd_una) {
-				/* Well, only one small jumplet in fast path... */
-				tcp_ack(sk, skb, FLAG_DATA);
-				tcp_data_snd_check(sk);
-				if (!inet_csk_ack_scheduled(sk))
-					goto no_ack;
-			}
-
-			__tcp_ack_snd_check(sk, 0);
-no_ack:
-			if (eaten)
-				kfree_skb_partial(skb, fragstolen);
-			sk->sk_data_ready(sk);
-			return;
-		}
-	}
-
-slow_path:
 	if (len < (th->doff << 2) || tcp_checksum_complete(skb))
 		goto csum_error;
 
 	if (!th->ack && !th->rst && !th->syn)
 		goto discard;
 
-	/*
-	 *	Standard slow path.
-	 */
-
 	if (!tcp_validate_incoming(sk, skb, th, 1))
 		return;
 
-step5:
-	if (tcp_ack(sk, skb, FLAG_SLOWPATH | FLAG_UPDATE_TS_RECENT) < 0)
+	if (tcp_ack(sk, skb, FLAG_UPDATE_TS_RECENT) < 0)
 		goto discard;
 
 	tcp_rcv_rtt_measure_ts(sk, skb);
@@ -5587,12 +5347,6 @@ void tcp_finish_connect(struct sock *sk, struct sk_buff *skb)
 
 	if (sock_flag(sk, SOCK_KEEPOPEN))
 		inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tp));
-
-	if (!tp->rx_opt.snd_wscale)
-		__tcp_fast_path_on(tp, tp->snd_wnd);
-	else
-		tp->pred_flags = 0;
-
 }
 
 static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
@@ -5721,7 +5475,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
 		tcp_ecn_rcv_synack(tp, th);
 
 		tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
-		tcp_ack(sk, skb, FLAG_SLOWPATH);
+		tcp_ack(sk, skb, 0);
 
 		/* Ok.. it's good. Set up sequence numbers and
 		 * move to established.
@@ -5957,8 +5711,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 		return 0;
 
 	/* step 5: check the ACK field */
-	acceptable = tcp_ack(sk, skb, FLAG_SLOWPATH |
-				      FLAG_UPDATE_TS_RECENT |
+
+	acceptable = tcp_ack(sk, skb, FLAG_UPDATE_TS_RECENT |
 				      FLAG_NO_CHALLENGE_ACK) > 0;
 
 	if (!acceptable) {
@@ -6026,7 +5780,6 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 		tp->lsndtime = tcp_jiffies32;
 
 		tcp_initialize_rcv_mss(sk);
-		tcp_fast_path_on(tp);
 		break;
 
 	case TCP_FIN_WAIT1: {