Re: [PATCH mptcp-next v8 2/4] mptcp: add statistics for mptcp socket in use

[Paolo Abeni <pabeni@redhat.com>]

On Thu, 2022-12-08 at 10:45 +0800, menglong8.dong@gmail.com wrote:
> diff --git a/net/mptcp/token.c b/net/mptcp/token.c
> index 65430f314a68..54064146175f 100644
> --- a/net/mptcp/token.c
> +++ b/net/mptcp/token.c
> @@ -175,6 +175,9 @@ int mptcp_token_new_connect(struct sock *sk)
>  	__sk_nulls_add_node_rcu((struct sock *)msk, &bucket->msk_chain);
>  	bucket->chain_len++;
>  	spin_unlock_bh(&bucket->lock);
> +	sock_prot_inuse_add(sock_net(subflow->conn),
> +			    subflow->conn->sk_prot,
> +			    1);

Whoops, sorry for not noticing the above earlier...
Here it would be better rename the mptcp_token_new_connect argument to
'ssk', and add a new local variable:

	struct sock *sk = subflow->conn;

and replace the '(struct sock *)msk', 'subflow->conn' above with 'sk'. 

Side note: the kunit crash is due to build_icsk() being too naive: it
creates a completely zeroed inet_connection_sock, while after this
patch mptcp_token_new_connect() requires that the sk_prot field is
initialized, too. 

The issue could be addresses with an addtional chunk in token_test.c.
Note that for token's test sake, sk_prot could be initialized to any
available/already exported proto.
---
diff --git a/net/mptcp/token_test.c b/net/mptcp/token_test.c
index 5d984bec1cd8..3bffe8d0d36f 100644
--- a/net/mptcp/token_test.c
+++ b/net/mptcp/token_test.c
@@ -36,6 +36,9 @@ static struct inet_connection_sock *build_icsk(struct kunit *test)
 	icsk = kunit_kzalloc(test, sizeof(struct inet_connection_sock),
 			     GFP_USER);
 	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, icsk);
+
+	/* be sure the tocken helpers can dereference sk->sk_prot */
+	icsk->icsk_inet.sk.sk_prot = &tcp_prot;
 	return icsk;
 }