net: TCP_MSS_DEFAULT, TCP_MSS_DESIRED
Define two symbols needed in both kernel and user space.
Remove old (somewhat incorrect) kernel variant that wasn't used in
most cases. Default should apply to both RMSS and SMSS (RFC2581).
Replace numeric constants with defined symbols.
Stand-alone patch, originally developed for TCPCT.
Signed-off-by: William.Allen.Simpson@gmail.com
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index eeecb85..32d7d77 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -81,6 +81,12 @@
TCP_DATA_OFFSET = __cpu_to_be32(0xF0000000)
};
+/*
+ * TCP general constants
+ */
+#define TCP_MSS_DEFAULT 536U /* IPv4 (RFC1122, RFC2581) */
+#define TCP_MSS_DESIRED 1220U /* IPv6 (tunneled), EDNS0 (RFC3226) */
+
/* TCP socket options */
#define TCP_NODELAY 1 /* Turn off Nagle's algorithm. */
#define TCP_MAXSEG 2 /* Limit MSS */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index bf20f88..325bfcf 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -62,9 +62,6 @@
/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
#define TCP_MIN_MSS 88U
-/* Minimal RCV_MSS. */
-#define TCP_MIN_RCVMSS 536U
-
/* The least MTU to use for probing */
#define TCP_BASE_MSS 512
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index be0c5bf..cc306ac 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -140,7 +140,7 @@
* "len" is invariant segment length, including TCP header.
*/
len += skb->data - skb_transport_header(skb);
- if (len >= TCP_MIN_RCVMSS + sizeof(struct tcphdr) ||
+ if (len >= TCP_MSS_DEFAULT + sizeof(struct tcphdr) ||
/* If PSH is not set, packet should be
* full sized, provided peer TCP is not badly broken.
* This observation (if it is correct 8)) allows
@@ -411,7 +411,7 @@
unsigned int hint = min_t(unsigned int, tp->advmss, tp->mss_cache);
hint = min(hint, tp->rcv_wnd / 2);
- hint = min(hint, TCP_MIN_RCVMSS);
+ hint = min(hint, TCP_MSS_DEFAULT);
hint = max(hint, TCP_MIN_MSS);
inet_csk(sk)->icsk_ack.rcv_mss = hint;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 657ae33..cf7f208 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -217,7 +217,7 @@
if (inet->opt)
inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
- tp->rx_opt.mss_clamp = 536;
+ tp->rx_opt.mss_clamp = TCP_MSS_DEFAULT;
/* Socket identity is still unknown (sport may be zero).
* However we set state to SYN-SENT and not releasing socket
@@ -1268,7 +1268,7 @@
goto drop_and_free;
tcp_clear_options(&tmp_opt);
- tmp_opt.mss_clamp = 536;
+ tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
tmp_opt.user_mss = tcp_sk(sk)->rx_opt.user_mss;
tcp_parse_options(skb, &tmp_opt, 0, dst);
@@ -1815,7 +1815,7 @@
*/
tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
tp->snd_cwnd_clamp = ~0;
- tp->mss_cache = 536;
+ tp->mss_cache = TCP_MSS_DEFAULT;
tp->reordering = sysctl_tcp_reordering;
icsk->icsk_ca_ops = &tcp_init_congestion_ops;
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index a9d34e2..4be2228 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -476,7 +476,7 @@
if (newtp->af_specific->md5_lookup(sk, newsk))
newtp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED;
#endif
- if (skb->len >= TCP_MIN_RCVMSS+newtp->tcp_header_len)
+ if (skb->len >= TCP_MSS_DEFAULT + newtp->tcp_header_len)
newicsk->icsk_ack.last_seg_size = skb->len - newtp->tcp_header_len;
newtp->rx_opt.mss_clamp = req->mss;
TCP_ECN_openreq_child(newtp, req);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 696a22f..de70909 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1851,7 +1851,7 @@
*/
tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
tp->snd_cwnd_clamp = ~0;
- tp->mss_cache = 536;
+ tp->mss_cache = TCP_MSS_DEFAULT;
tp->reordering = sysctl_tcp_reordering;