1 files changed, 39 insertions, 42 deletions

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 681882a40968..d8d28ba169b4 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -22,33 +22,21 @@
 #include <linux/gfp.h>
 #include <net/tcp.h>
 
-static u32 tcp_retransmit_stamp(const struct sock *sk)
-{
-	u32 start_ts = tcp_sk(sk)->retrans_stamp;
-
-	if (unlikely(!start_ts)) {
-		struct sk_buff *head = tcp_rtx_queue_head(sk);
-
-		if (!head)
-			return 0;
-		start_ts = tcp_skb_timestamp(head);
-	}
-	return start_ts;
-}
-
 static u32 tcp_clamp_rto_to_user_timeout(const struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	u32 elapsed, start_ts;
+	s32 remaining;
 
-	start_ts = tcp_retransmit_stamp(sk);
-	if (!icsk->icsk_user_timeout || !start_ts)
+	start_ts = tcp_sk(sk)->retrans_stamp;
+	if (!icsk->icsk_user_timeout)
 		return icsk->icsk_rto;
 	elapsed = tcp_time_stamp(tcp_sk(sk)) - start_ts;
-	if (elapsed >= icsk->icsk_user_timeout)
+	remaining = icsk->icsk_user_timeout - elapsed;
+	if (remaining <= 0)
 		return 1; /* user timeout has passed; fire ASAP */
-	else
-		return min_t(u32, icsk->icsk_rto, msecs_to_jiffies(icsk->icsk_user_timeout - elapsed));
+
+	return min_t(u32, icsk->icsk_rto, msecs_to_jiffies(remaining));
 }
 
 /**
@@ -136,7 +124,7 @@ static int tcp_out_of_resources(struct sock *sk, bool do_reset)
  */
 static int tcp_orphan_retries(struct sock *sk, bool alive)
 {
-	int retries = sock_net(sk)->ipv4.sysctl_tcp_orphan_retries; /* May be zero. */
+	int retries = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_orphan_retries); /* May be zero. */
 
 	/* We know from an ICMP that something is wrong. */
 	if (sk->sk_err_soft && !alive)
@@ -156,7 +144,7 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
 	int mss;
 
 	/* Black hole detection */
-	if (!net->ipv4.sysctl_tcp_mtu_probing)
+	if (!READ_ONCE(net->ipv4.sysctl_tcp_mtu_probing))
 		return;
 
 	if (!icsk->icsk_mtup.enabled) {
@@ -172,7 +160,20 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
 	tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
 }
 
+static unsigned int tcp_model_timeout(struct sock *sk,
+				      unsigned int boundary,
+				      unsigned int rto_base)
+{
+	unsigned int linear_backoff_thresh, timeout;
 
+	linear_backoff_thresh = ilog2(TCP_RTO_MAX / rto_base);
+	if (boundary <= linear_backoff_thresh)
+		timeout = ((2 << boundary) - 1) * rto_base;
+	else
+		timeout = ((2 << linear_backoff_thresh) - 1) * rto_base +
+			(boundary - linear_backoff_thresh) * TCP_RTO_MAX;
+	return jiffies_to_msecs(timeout);
+}
 /**
  *  retransmits_timed_out() - returns true if this connection has timed out
  *  @sk:       The current socket
@@ -190,27 +191,21 @@ static bool retransmits_timed_out(struct sock *sk,
 				  unsigned int boundary,
 				  unsigned int timeout)
 {
-	const unsigned int rto_base = TCP_RTO_MIN;
-	unsigned int linear_backoff_thresh, start_ts;
+	unsigned int start_ts;
 
 	if (!inet_csk(sk)->icsk_retransmits)
 		return false;
 
-	start_ts = tcp_retransmit_stamp(sk);
-	if (!start_ts)
-		return false;
-
+	start_ts = tcp_sk(sk)->retrans_stamp;
 	if (likely(timeout == 0)) {
-		linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base);
-
-		if (boundary <= linear_backoff_thresh)
-			timeout = ((2 << boundary) - 1) * rto_base;
-		else
-			timeout = ((2 << linear_backoff_thresh) - 1) * rto_base +
-				(boundary - linear_backoff_thresh) * TCP_RTO_MAX;
-		timeout = jiffies_to_msecs(timeout);
+		unsigned int rto_base = TCP_RTO_MIN;
+
+		if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
+			rto_base = tcp_timeout_init(sk);
+		timeout = tcp_model_timeout(sk, boundary, rto_base);
 	}
-	return (tcp_time_stamp(tcp_sk(sk)) - start_ts) >= timeout;
+
+	return (s32)(tcp_time_stamp(tcp_sk(sk)) - start_ts - timeout) >= 0;
 }
 
 /* A write timeout has occurred. Process the after effects. */
@@ -231,7 +226,7 @@ static int tcp_write_timeout(struct sock *sk)
 		retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries;
 		expired = icsk->icsk_retransmits >= retry_until;
 	} else {
-		if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1, 0)) {
+		if (retransmits_timed_out(sk, READ_ONCE(net->ipv4.sysctl_tcp_retries1), 0)) {
 			/* Black hole detection */
 			tcp_mtu_probing(icsk, sk);
 
@@ -240,7 +235,7 @@ static int tcp_write_timeout(struct sock *sk)
 			sk_rethink_txhash(sk);
 		}
 
-		retry_until = net->ipv4.sysctl_tcp_retries2;
+		retry_until = READ_ONCE(net->ipv4.sysctl_tcp_retries2);
 		if (sock_flag(sk, SOCK_DEAD)) {
 			const bool alive = icsk->icsk_rto < TCP_RTO_MAX;
 
@@ -367,7 +362,7 @@ static void tcp_probe_timer(struct sock *sk)
 		 (s32)(tcp_time_stamp(tp) - start_ts) > icsk->icsk_user_timeout)
 		goto abort;
 
-	max_probes = sock_net(sk)->ipv4.sysctl_tcp_retries2;
+	max_probes = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_retries2);
 	if (sock_flag(sk, SOCK_DEAD)) {
 		const bool alive = inet_csk_rto_backoff(icsk, TCP_RTO_MAX) < TCP_RTO_MAX;
 
@@ -550,18 +545,20 @@ out_reset_timer:
 	 * linear-timeout retransmissions into a black hole
 	 */
 	if (sk->sk_state == TCP_ESTABLISHED &&
-	    (tp->thin_lto || net->ipv4.sysctl_tcp_thin_linear_timeouts) &&
+	    (tp->thin_lto || READ_ONCE(net->ipv4.sysctl_tcp_thin_linear_timeouts)) &&
 	    tcp_stream_is_thin(tp) &&
 	    icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) {
 		icsk->icsk_backoff = 0;
-		icsk->icsk_rto = min(__tcp_set_rto(tp), TCP_RTO_MAX);
+		icsk->icsk_rto = clamp(__tcp_set_rto(tp),
+				       tcp_rto_min(sk),
+				       TCP_RTO_MAX);
 	} else {
 		/* Use normal (exponential) backoff */
 		icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
 	}
 	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 				  tcp_clamp_rto_to_user_timeout(sk), TCP_RTO_MAX);
-	if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1 + 1, 0))
+	if (retransmits_timed_out(sk, READ_ONCE(net->ipv4.sysctl_tcp_retries1) + 1, 0))
 		__sk_dst_reset(sk);
 
 out:;