[RFC v2 mptcp-next 04/12] mptcp: subflow: split subflow_init_req into helpers

[Florian Westphal]

When syncookie support is added, we will need to add a variant of
subflow_init_req() helper.  It will do almost same thing except
that it will not compute/add a token to the mptcp token tree.

To avoid excess copy&paste, this commit splits away part of the
code into helpers that can then be re-used from the 'no insert'
function added in a followup change.

Signed-off-by: Florian Westphal <f...@strlen.de>
---
 net/mptcp/subflow.c | 49 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 14 deletions(-)

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 9526566ec153..800e7d472dcd 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -91,17 +91,9 @@ static struct mptcp_sock *subflow_token_join_request(struct 
request_sock *req,
        return msk;
 }
 
-static void subflow_init_req(struct request_sock *req,
-                            const struct sock *sk_listener,
-                            struct sk_buff *skb)
+static int __subflow_init_req(struct request_sock *req, const struct sock 
*sk_listener)
 {
-       struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
        struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
-       struct mptcp_options_received mp_opt;
-
-       pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
-
-       mptcp_get_options(skb, &mp_opt);
 
        subflow_req->mp_capable = 0;
        subflow_req->mp_join = 0;
@@ -113,18 +105,47 @@ static void subflow_init_req(struct request_sock *req,
         * TCP option space.
         */
        if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
-               return;
+               return -EINVAL;
 #endif
 
-       if (mp_opt.mp_capable) {
+       return 0;
+}
+
+static int __subflow_check_options(const struct mptcp_options_received *mp_opt,
+                                  struct request_sock *req)
+{
+       if (mp_opt->mp_capable) {
                SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
 
-               if (mp_opt.mp_join)
-                       return;
-       } else if (mp_opt.mp_join) {
+               if (mp_opt->mp_join)
+                       return -EINVAL;
+       } else if (mp_opt->mp_join) {
                SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
        }
 
+       return 0;
+}
+
+static void subflow_init_req(struct request_sock *req,
+                            const struct sock *sk_listener,
+                            struct sk_buff *skb)
+{
+       struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
+       struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
+       struct mptcp_options_received mp_opt;
+       int ret;
+
+       pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
+
+       ret = __subflow_init_req(req, sk_listener);
+       if (ret)
+               return;
+
+       mptcp_get_options(skb, &mp_opt);
+       ret = __subflow_check_options(&mp_opt, req);
+       if (ret)
+               return;
+
        if (mp_opt.mp_capable && listener->request_mptcp) {
                int err, retries = 4;
 
-- 
2.26.2