Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 0488607..638d7b4 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -72,6 +72,9 @@
 	__skb_unlink(skb, &sk->sk_write_queue);
 	tcp_rbtree_insert(&sk->tcp_rtx_queue, skb);
 
+	if (tp->highest_sack == NULL)
+		tp->highest_sack = skb;
+
 	tp->packets_out += tcp_skb_pcount(skb);
 	if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)
 		tcp_rearm_rto(sk);
@@ -659,7 +662,8 @@
 				       unsigned int mss, struct sk_buff *skb,
 				       struct tcp_out_options *opts,
 				       const struct tcp_md5sig_key *md5,
-				       struct tcp_fastopen_cookie *foc)
+				       struct tcp_fastopen_cookie *foc,
+				       enum tcp_synack_type synack_type)
 {
 	struct inet_request_sock *ireq = inet_rsk(req);
 	unsigned int remaining = MAX_TCP_OPTION_SPACE;
@@ -674,7 +678,8 @@
 		 * rather than TS in order to fit in better with old,
 		 * buggy kernels, but that was deemed to be unnecessary.
 		 */
-		ireq->tstamp_ok &= !ireq->sack_ok;
+		if (synack_type != TCP_SYNACK_COOKIE)
+			ireq->tstamp_ok &= !ireq->sack_ok;
 	}
 #endif
 
@@ -755,8 +760,9 @@
 			min_t(unsigned int, eff_sacks,
 			      (remaining - TCPOLEN_SACK_BASE_ALIGNED) /
 			      TCPOLEN_SACK_PERBLOCK);
-		size += TCPOLEN_SACK_BASE_ALIGNED +
-			opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK;
+		if (likely(opts->num_sack_blocks))
+			size += TCPOLEN_SACK_BASE_ALIGNED +
+				opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK;
 	}
 
 	return size;
@@ -1044,6 +1050,10 @@
 
 		if (unlikely(!skb))
 			return -ENOBUFS;
+		/* retransmit skbs might have a non zero value in skb->dev
+		 * because skb->dev is aliased with skb->rbnode.rb_left
+		 */
+		skb->dev = NULL;
 	}
 
 	inet = inet_sk(sk);
@@ -1494,6 +1504,7 @@
 	return __tcp_mtu_to_mss(sk, pmtu) -
 	       (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr));
 }
+EXPORT_SYMBOL(tcp_mtu_to_mss);
 
 /* Inverse of above */
 int tcp_mss_to_mtu(struct sock *sk, int mss)
@@ -1644,7 +1655,8 @@
 	 * window, and remember whether we were cwnd-limited then.
 	 */
 	if (!before(tp->snd_una, tp->max_packets_seq) ||
-	    tp->packets_out > tp->max_packets_out) {
+	    tp->packets_out > tp->max_packets_out ||
+	    is_cwnd_limited) {
 		tp->max_packets_out = tp->packets_out;
 		tp->max_packets_seq = tp->snd_nxt;
 		tp->is_cwnd_limited = is_cwnd_limited;
@@ -1724,7 +1736,7 @@
 	u32 bytes, segs;
 
 	bytes = min_t(unsigned long,
-		      sk->sk_pacing_rate >> sk->sk_pacing_shift,
+		      sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift),
 		      sk->sk_gso_max_size - 1 - MAX_TCP_HEADER);
 
 	/* Goal is to send at least one packet per ms,
@@ -2259,7 +2271,7 @@
 
 	limit = max_t(unsigned long,
 		      2 * skb->truesize,
-		      sk->sk_pacing_rate >> sk->sk_pacing_shift);
+		      sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift));
 	if (sk->sk_pacing_status == SK_PACING_NONE)
 		limit = min_t(unsigned long, limit,
 			      sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes);
@@ -2437,6 +2449,14 @@
 		if (tcp_small_queue_check(sk, skb, 0))
 			break;
 
+		/* Argh, we hit an empty skb(), presumably a thread
+		 * is sleeping in sendmsg()/sk_stream_wait_memory().
+		 * We do not want to send a pure-ack packet and have
+		 * a strange looking rtx queue with empty packet(s).
+		 */
+		if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq)
+			break;
+
 		if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp)))
 			break;
 
@@ -2458,6 +2478,10 @@
 	else
 		tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED);
 
+	is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd);
+	if (likely(sent_pkts || is_cwnd_limited))
+		tcp_cwnd_validate(sk, is_cwnd_limited);
+
 	if (likely(sent_pkts)) {
 		if (tcp_in_cwnd_reduction(sk))
 			tp->prr_out += sent_pkts;
@@ -2465,8 +2489,6 @@
 		/* Send one loss probe per tail loss episode. */
 		if (push_one != 2)
 			tcp_schedule_loss_probe(sk, false);
-		is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tp->snd_cwnd);
-		tcp_cwnd_validate(sk, is_cwnd_limited);
 		return false;
 	}
 	return !tp->packets_out && !tcp_write_queue_empty(sk);
@@ -2546,6 +2568,11 @@
 	int pcount;
 	int mss = tcp_current_mss(sk);
 
+	/* At most one outstanding TLP */
+	if (tp->tlp_high_seq)
+		goto rearm_timer;
+
+	tp->tlp_retrans = 0;
 	skb = tcp_send_head(sk);
 	if (skb && tcp_snd_wnd_test(tp, skb, mss)) {
 		pcount = tp->packets_out;
@@ -2563,10 +2590,6 @@
 		return;
 	}
 
-	/* At most one outstanding TLP retransmission. */
-	if (tp->tlp_high_seq)
-		goto rearm_timer;
-
 	if (skb_still_in_host_queue(sk, skb))
 		goto rearm_timer;
 
@@ -2588,10 +2611,12 @@
 	if (__tcp_retransmit_skb(sk, skb, 1))
 		goto rearm_timer;
 
+	tp->tlp_retrans = 1;
+
+probe_sent:
 	/* Record snd_nxt for loss detection. */
 	tp->tlp_high_seq = tp->snd_nxt;
 
-probe_sent:
 	NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES);
 	/* Reset s.t. tcp_rearm_rto will restart timer from now */
 	inet_csk(sk)->icsk_pending = 0;
@@ -2964,8 +2989,12 @@
 
 		tcp_skb_tsorted_save(skb) {
 			nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC);
-			err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) :
-				     -ENOBUFS;
+			if (nskb) {
+				nskb->dev = NULL;
+				err = tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC);
+			} else {
+				err = -ENOBUFS;
+			}
 		} tcp_skb_tsorted_restore(skb);
 
 		if (!err) {
@@ -3219,6 +3248,7 @@
 			if (!nskb)
 				return -ENOMEM;
 			INIT_LIST_HEAD(&nskb->tcp_tsorted_anchor);
+			tcp_highest_sack_replace(sk, skb, nskb);
 			tcp_rtx_queue_unlink_and_free(skb, sk);
 			__skb_header_release(nskb);
 			tcp_rbtree_insert(&sk->tcp_rtx_queue, nskb);
@@ -3305,7 +3335,7 @@
 #endif
 	skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4);
 	tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5,
-					     foc) + sizeof(*th);
+					     foc, synack_type) + sizeof(*th);
 
 	skb_push(skb, tcp_header_size);
 	skb_reset_transport_header(skb);
@@ -3806,6 +3836,7 @@
 		/* Cancel probe timer, if it is not required. */
 		icsk->icsk_probes_out = 0;
 		icsk->icsk_backoff = 0;
+		icsk->icsk_probes_tstamp = 0;
 		return;
 	}
 
@@ -3820,6 +3851,8 @@
 		 */
 		timeout = TCP_RESOURCE_PROBE_INTERVAL;
 	}
+
+	timeout = tcp_clamp_probe0_to_user_timeout(sk, timeout);
 	tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX, NULL);
 }