[PATCH v1 net-next] net: Deprecate SO_DEBUG and reclaim SOCK_DBG bit.

[Kuniyuki Iwashima <kuniyu@amazon.com>]

Recently, commit 8e5443d2b866 ("net: remove SOCK_DEBUG leftovers")
removed the last users of SOCK_DEBUG(), and commit b1dffcf0da22 ("net:
remove SOCK_DEBUG macro") removed the macro.

Now is the time to deprecate the oldest socket option.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 include/net/sock.h  | 1 -
 net/core/sock.c     | 6 +++---
 net/mptcp/sockopt.c | 4 +---
 net/smc/af_smc.c    | 5 ++---
 4 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index a9d99a9c583f..e20d55a36f9c 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -909,7 +909,6 @@ enum sock_flags {
 	SOCK_TIMESTAMP,
 	SOCK_ZAPPED,
 	SOCK_USE_WRITE_QUEUE, /* whether to call sk->sk_write_space in sock_wfree */
-	SOCK_DBG, /* %SO_DEBUG setting */
 	SOCK_RCVTSTAMP, /* %SO_TIMESTAMP setting */
 	SOCK_RCVTSTAMPNS, /* %SO_TIMESTAMPNS setting */
 	SOCK_LOCALROUTE, /* route locally only, %SO_DONTROUTE setting */
diff --git a/net/core/sock.c b/net/core/sock.c
index 88bf810394a5..0a58dc861908 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1194,10 +1194,9 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
 
 	switch (optname) {
 	case SO_DEBUG:
+		/* deprecated, but kept for compatibility. */
 		if (val && !sockopt_capable(CAP_NET_ADMIN))
 			ret = -EACCES;
-		else
-			sock_valbool_flag(sk, SOCK_DBG, valbool);
 		break;
 	case SO_REUSEADDR:
 		sk->sk_reuse = (valbool ? SK_CAN_REUSE : SK_NO_REUSE);
@@ -1619,7 +1618,8 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
 
 	switch (optname) {
 	case SO_DEBUG:
-		v.val = sock_flag(sk, SOCK_DBG);
+		/* deprecated. */
+		v.val = 0;
 		break;
 
 	case SO_DONTROUTE:
diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index da37e4541a5d..f6d90eef3d7c 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -81,7 +81,7 @@ static void mptcp_sol_socket_sync_intval(struct mptcp_sock *msk, int optname, in
 
 		switch (optname) {
 		case SO_DEBUG:
-			sock_valbool_flag(ssk, SOCK_DBG, !!val);
+			/* deprecated. */
 			break;
 		case SO_KEEPALIVE:
 			if (ssk->sk_prot->keepalive)
@@ -1458,8 +1458,6 @@ static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk)
 		sk_dst_reset(ssk);
 	}
 
-	sock_valbool_flag(ssk, SOCK_DBG, sock_flag(sk, SOCK_DBG));
-
 	if (inet_csk(sk)->icsk_ca_ops != inet_csk(ssk)->icsk_ca_ops)
 		tcp_set_congestion_control(ssk, msk->ca_name, false, true);
 	__tcp_sock_set_cork(ssk, !!msk->cork);
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 66763c74ab76..062e16a2766a 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -445,7 +445,6 @@ static int smc_bind(struct socket *sock, struct sockaddr *uaddr,
 			     (1UL << SOCK_LINGER) | \
 			     (1UL << SOCK_BROADCAST) | \
 			     (1UL << SOCK_TIMESTAMP) | \
-			     (1UL << SOCK_DBG) | \
 			     (1UL << SOCK_RCVTSTAMP) | \
 			     (1UL << SOCK_RCVTSTAMPNS) | \
 			     (1UL << SOCK_LOCALROUTE) | \
@@ -511,8 +510,8 @@ static void smc_copy_sock_settings_to_clc(struct smc_sock *smc)
 
 #define SK_FLAGS_CLC_TO_SMC ((1UL << SOCK_URGINLINE) | \
 			     (1UL << SOCK_KEEPOPEN) | \
-			     (1UL << SOCK_LINGER) | \
-			     (1UL << SOCK_DBG))
+			     (1UL << SOCK_LINGER))
+
 /* copy only settings and flags relevant for smc from clc to smc socket */
 static void smc_copy_sock_settings_to_smc(struct smc_sock *smc)
 {
-- 
2.30.2