tcp: Introduce mss_cache_set_by_ca for CCA to set MSS

Signed-off-by: Chia-Yu Chang <[email protected]>
minuscat · Aug 19, 2024 · 57f3db5 · 57f3db5
1 parent 10e5f2f
commit 57f3db5
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Showing 3 changed files with 4 additions and 2 deletions.
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
@@ -243,6 +243,7 @@ struct tcp_sock {
 	u32	snd_wnd;	/* The window we expect to receive	*/
 	u32	max_window;	/* Maximal window ever seen from peer	*/
 	u32	mss_cache;	/* Cached effective mss, not including SACKS */
+	bool    mss_cache_set_by_ca;
 
 	u32	window_clamp;	/* Maximal window to advertise		*/
 	u32	rcv_ssthresh;	/* Current window clamp			*/

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
@@ -444,6 +444,7 @@ void tcp_init_sock(struct sock *sk)
 	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 	tp->snd_cwnd_clamp = ~0;
 	tp->mss_cache = TCP_MSS_DEFAULT;
+	tp->mss_cache_set_by_ca = false;
 
 	tp->reordering = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_reordering);
 	tcp_assign_congestion_control(sk);

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
@@ -2018,7 +2018,7 @@ unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu)
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	int mss_now;
 
-	if (icsk->icsk_mtup.search_high > pmtu)
+	if (icsk->icsk_mtup.search_high > pmtu && !tp->mss_cache_set_by_ca)
 		icsk->icsk_mtup.search_high = pmtu;
 
 	mss_now = tcp_mtu_to_mss(sk, pmtu);
@@ -2048,7 +2048,7 @@ unsigned int tcp_current_mss(struct sock *sk)
 
 	mss_now = tp->mss_cache;
 
-	if (dst) {
+	if (dst && !tp->mss_cache_set_by_ca) {
 		u32 mtu = dst_mtu(dst);
 		if (mtu != inet_csk(sk)->icsk_pmtu_cookie)
 			mss_now = tcp_sync_mss(sk, mtu);