This is a note to let you know that I've just added the patch titled

    mptcp: remove MPTCP 'ifdef' in TCP SYN cookies

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mptcp-remove-mptcp-ifdef-in-tcp-syn-cookies.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From stable-owner@vger.kernel.org Sat Jan  7 02:46:48 2023
From: Mat Martineau <mathew.j.martineau@linux.intel.com>
Date: Fri,  6 Jan 2023 17:46:29 -0800
Subject: mptcp: remove MPTCP 'ifdef' in TCP SYN cookies
To: stable@vger.kernel.org, gregkh@linuxfoundation.org
Cc: Matthieu Baerts <matthieu.baerts@tessares.net>, pabeni@redhat.com, mptcp@lists.linux.dev, Mat Martineau <mathew.j.martineau@linux.intel.com>, Jakub Kicinski <kuba@kernel.org>
Message-ID: <20230107014631.449550-3-mathew.j.martineau@linux.intel.com>

From: Mat Martineau <mathew.j.martineau@linux.intel.com>

From: Matthieu Baerts <matthieu.baerts@tessares.net>

commit 3fff88186f047627bb128d65155f42517f8e448f upstream.

To ease the maintenance, it is often recommended to avoid having #ifdef
preprocessor conditions.

Here the section related to CONFIG_MPTCP was quite short but the next
commit needs to add more code around. It is then cleaner to move
specific MPTCP code to functions located in net/mptcp directory.

Now that mptcp_subflow_request_sock_ops structure can be static, it can
also be marked as "read only after init".

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Cc: stable@vger.kernel.org # 5.10
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/net/mptcp.h   |   12 ++++++++++--
 net/ipv4/syncookies.c |    7 +++----
 net/mptcp/subflow.c   |   12 +++++++++++-
 3 files changed, 24 insertions(+), 7 deletions(-)

--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -58,8 +58,6 @@ struct mptcp_out_options {
 };
 
 #ifdef CONFIG_MPTCP
-extern struct request_sock_ops mptcp_subflow_request_sock_ops;
-
 void mptcp_init(void);
 
 static inline bool sk_is_mptcp(const struct sock *sk)
@@ -133,6 +131,9 @@ void mptcp_seq_show(struct seq_file *seq
 int mptcp_subflow_init_cookie_req(struct request_sock *req,
 				  const struct sock *sk_listener,
 				  struct sk_buff *skb);
+struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
+					       struct sock *sk_listener,
+					       bool attach_listener);
 #else
 
 static inline void mptcp_init(void)
@@ -208,6 +209,13 @@ static inline int mptcp_subflow_init_coo
 {
 	return 0; /* TCP fallback */
 }
+
+static inline struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
+							     struct sock *sk_listener,
+							     bool attach_listener)
+{
+	return NULL;
+}
 #endif /* CONFIG_MPTCP */
 
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -290,12 +290,11 @@ struct request_sock *cookie_tcp_reqsk_al
 	struct tcp_request_sock *treq;
 	struct request_sock *req;
 
-#ifdef CONFIG_MPTCP
 	if (sk_is_mptcp(sk))
-		ops = &mptcp_subflow_request_sock_ops;
-#endif
+		req = mptcp_subflow_reqsk_alloc(ops, sk, false);
+	else
+		req = inet_reqsk_alloc(ops, sk, false);
 
-	req = inet_reqsk_alloc(ops, sk, false);
 	if (!req)
 		return NULL;
 
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -359,7 +359,7 @@ do_reset:
 	mptcp_subflow_reset(sk);
 }
 
-struct request_sock_ops mptcp_subflow_request_sock_ops;
+static struct request_sock_ops mptcp_subflow_request_sock_ops __ro_after_init;
 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init;
 
 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
@@ -411,6 +411,16 @@ drop:
 }
 #endif
 
+struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
+					       struct sock *sk_listener,
+					       bool attach_listener)
+{
+	ops = &mptcp_subflow_request_sock_ops;
+
+	return inet_reqsk_alloc(ops, sk_listener, attach_listener);
+}
+EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc);
+
 /* validate hmac received in third ACK */
 static bool subflow_hmac_valid(const struct request_sock *req,
 			       const struct mptcp_options_received *mp_opt)


Patches currently in stable-queue which might be from stable-owner@vger.kernel.org are

queue-5.10/mptcp-use-proper-req-destructor-for-ipv6.patch
queue-5.10/mptcp-remove-mptcp-ifdef-in-tcp-syn-cookies.patch
queue-5.10/mptcp-dedicated-request-sock-for-subflow-in-v6.patch
queue-5.10/mptcp-mark-ops-structures-as-ro_after_init.patch