Merge branch 'udplite-dccp-print-deprecation-notice'

Kuniyuki Iwashima says:

====================
udplite/dccp: Print deprecation notice.

UDP-Lite is assumed to have no users for 7 years, and DCCP is
orphaned for 7 years too.

Let's add deprecation notice and see if anyone responds to it.
====================

Link: https://lore.kernel.org/r/20230614194705.90673-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

net/dccp/proto.c

@@ -191,6 +191,9 @@ int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized)
 	struct dccp_sock *dp = dccp_sk(sk);
 	struct inet_connection_sock *icsk = inet_csk(sk);
 
+	pr_warn_once("DCCP is deprecated and scheduled to be removed in 2025, "
+		     "please contact the netdev mailing list\n");
+
 	icsk->icsk_rto		= DCCP_TIMEOUT_INIT;
 	icsk->icsk_syn_retries	= sysctl_dccp_request_retries;
 	sk->sk_state		= DCCP_CLOSED;

net/ipv4/udplite.c

@@ -22,6 +22,8 @@ static int udplite_sk_init(struct sock *sk)
 {
 	udp_init_sock(sk);
 	udp_sk(sk)->pcflag = UDPLITE_BIT;
+	pr_warn_once("UDP-Lite is deprecated and scheduled to be removed in 2025, "
+		     "please contact the netdev mailing list\n");
 	return 0;
 }
 

net/ipv6/udplite.c

@@ -8,6 +8,8 @@
  *  Changes:
  *  Fixes:
  */
+#define pr_fmt(fmt) "UDPLite6: " fmt
+
 #include <linux/export.h>
 #include <linux/proc_fs.h>
 #include "udp_impl.h"
@@ -16,6 +18,8 @@ static int udplitev6_sk_init(struct sock *sk)
 {
 	udpv6_init_sock(sk);
 	udp_sk(sk)->pcflag = UDPLITE_BIT;
+	pr_warn_once("UDP-Lite is deprecated and scheduled to be removed in 2025, "
+		     "please contact the netdev mailing list\n");
 	return 0;
 }