diff mbox series

[v6,net-next,02/14] tcp: create FLAG_TS_PROGRESS

Message ID 20241227191211.12485-3-chia-yu.chang@nokia-bell-labs.com (mailing list archive)
State Deferred
Delegated to: Netdev Maintainers
Headers show
Series AccECN protocol preparation patch series | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 6 of 6 maintainers
netdev/build_clang success Errors and warnings before: 3 this patch: 3
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 2 this patch: 2
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 98 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 1 this patch: 1
netdev/source_inline success Was 0 now: 0

Commit Message

Chia-Yu Chang (Nokia) Dec. 27, 2024, 7:11 p.m. UTC 
From: Ilpo Järvinen <ij@kernel.org>

Whenever timestamp advances, it declares progress which
can be used by the other parts of the stack to decide that
the ACK is the most recent one seen so far.

AccECN will use this flag when deciding whether to use the
ACK to update AccECN state or not.

Signed-off-by: Ilpo Järvinen <ij@kernel.org>
Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/tcp_input.c | 37 ++++++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 9 deletions(-)
diff mbox series

Patch

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index f3691c1cdc83..eebe3a99aa90 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -102,6 +102,7 @@  int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
 #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_TS_PROGRESS	0x40000 /* Positive timestamp delta */
 
 #define FLAG_ACKED		(FLAG_DATA_ACKED|FLAG_SYN_ACKED)
 #define FLAG_NOT_DUP		(FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED)
@@ -3813,8 +3814,16 @@  static void tcp_store_ts_recent(struct tcp_sock *tp)
 	tp->rx_opt.ts_recent_stamp = ktime_get_seconds();
 }
 
-static void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq)
+static int __tcp_replace_ts_recent(struct tcp_sock *tp, s32 tstamp_delta)
 {
+	tcp_store_ts_recent(tp);
+	return tstamp_delta > 0 ? FLAG_TS_PROGRESS : 0;
+}
+
+static int tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq)
+{
+	s32 delta;
+
 	if (tp->rx_opt.saw_tstamp && !after(seq, tp->rcv_wup)) {
 		/* PAWS bug workaround wrt. ACK frames, the PAWS discard
 		 * extra check below makes sure this can only happen
@@ -3823,9 +3832,13 @@  static void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq)
 		 * Not only, also it occurs for expired timestamps.
 		 */
 
-		if (tcp_paws_check(&tp->rx_opt, 0))
-			tcp_store_ts_recent(tp);
+		if (tcp_paws_check(&tp->rx_opt, 0)) {
+			delta = tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent;
+			return __tcp_replace_ts_recent(tp, delta);
+		}
 	}
+
+	return 0;
 }
 
 /* This routine deals with acks during a TLP episode and ends an episode by
@@ -3982,7 +3995,7 @@  static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	 * is in window.
 	 */
 	if (flag & FLAG_UPDATE_TS_RECENT)
-		tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
+		flag |= tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
 
 	if ((flag & (FLAG_SLOWPATH | FLAG_SND_UNA_ADVANCED)) ==
 	    FLAG_SND_UNA_ADVANCED) {
@@ -6140,6 +6153,8 @@  void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
 	    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;
+		s32 delta = 0;
+		int flag = 0;
 
 		/* Timestamp header prediction: tcp_header_len
 		 * is automatically equal to th->doff*4 due to pred_flags
@@ -6152,8 +6167,10 @@  void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
 			if (!tcp_parse_aligned_timestamp(tp, th))
 				goto slow_path;
 
+			delta = tp->rx_opt.rcv_tsval -
+				tp->rx_opt.ts_recent;
 			/* If PAWS failed, check it more carefully in slow path */
-			if ((s32)(tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent) < 0)
+			if (delta < 0)
 				goto slow_path;
 
 			/* DO NOT update ts_recent here, if checksum fails
@@ -6173,12 +6190,13 @@  void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
 				if (tcp_header_len ==
 				    (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) &&
 				    tp->rcv_nxt == tp->rcv_wup)
-					tcp_store_ts_recent(tp);
+					flag |= __tcp_replace_ts_recent(tp,
+									delta);
 
 				/* We know that such packets are checksummed
 				 * on entry.
 				 */
-				tcp_ack(sk, skb, 0);
+				tcp_ack(sk, skb, flag);
 				__kfree_skb(skb);
 				tcp_data_snd_check(sk);
 				/* When receiving pure ack in fast path, update
@@ -6209,7 +6227,8 @@  void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
 			if (tcp_header_len ==
 			    (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) &&
 			    tp->rcv_nxt == tp->rcv_wup)
-				tcp_store_ts_recent(tp);
+				flag |= __tcp_replace_ts_recent(tp,
+								delta);
 
 			tcp_rcv_rtt_measure_ts(sk, skb);
 
@@ -6224,7 +6243,7 @@  void tcp_rcv_established(struct sock *sk, struct sk_buff *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_ack(sk, skb, flag | FLAG_DATA);
 				tcp_data_snd_check(sk);
 				if (!inet_csk_ack_scheduled(sk))
 					goto no_ack;