[PATCH mptcp-net] mptcp: sockopt: set timestamp flags on subflow socket, not msk

[Gang Yan <gang.yan@linux.dev>]

From: Gang Yan <yangang@kylinos.cn>

Both mptcp_setsockopt_sol_socket_tstamp() and
mptcp_setsockopt_sol_socket_timestamping() iterate over subflows,
acquire the subflow socket lock, but then erroneously pass the MPTCP
msk socket to sock_set_timestamp() / sock_set_timestamping() instead
of the subflow ssk. As a result, the timestamp flags are set on the
wrong socket and have no effect on the actual subflows.

Pass ssk instead of sk to both helpers.

Fixes: 3f4f958c3a3c ("mptcp: sockopt: propagate timestamp request to subflows")
Fixes: 6c9a0a0f2333 ("mptcp: setsockopt: convert to mptcp_setsockopt_sol_socket_timestamping()")
Assisted-by: GLM-5.1
Signed-off-by: Gang Yan <yangang@kylinos.cn>
---
 net/mptcp/sockopt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index de90a2897d2d..79db15903e7a 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -161,7 +161,7 @@ static int mptcp_setsockopt_sol_socket_tstamp(struct mptcp_sock *msk, int optnam
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 		bool slow = lock_sock_fast(ssk);
 
-		sock_set_timestamp(sk, optname, !!val);
+		sock_set_timestamp(ssk, optname, !!val);
 		unlock_sock_fast(ssk, slow);
 	}
 
@@ -237,7 +237,7 @@ static int mptcp_setsockopt_sol_socket_timestamping(struct mptcp_sock *msk,
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 		bool slow = lock_sock_fast(ssk);
 
-		sock_set_timestamping(sk, optname, timestamping);
+		sock_set_timestamping(ssk, optname, timestamping);
 		unlock_sock_fast(ssk, slow);
 	}
 
-- 
2.43.0