Revert "bpf: Extend bpf_skc_to_mptcp_sock to MPTCP sock"

bpf_core_cast() can be used in mptcp_subflow bpf_iter selftests to get the
msk, instead of using bpf_skc_to_mptcp_sock(). No need to add this patch
anymore, revert it.

Signed-off-by: Geliang Tang <[email protected]>

Author: Geliang Tang

include/net/mptcp.h

@@ -323,9 +323,9 @@ static inline void mptcpv6_handle_mapped(struct sock *sk, bool mapped) { }
 #endif
 
 #if defined(CONFIG_MPTCP) && defined(CONFIG_BPF_SYSCALL)
-struct mptcp_sock *bpf_mptcp_sock_from_sock(struct sock *sk);
+struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk);
 #else
-static inline struct mptcp_sock *bpf_mptcp_sock_from_sock(struct sock *sk) { return NULL; }
+static inline struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk) { return NULL; }
 #endif
 
 #if !IS_ENABLED(CONFIG_MPTCP)

net/core/filter.c

@@ -11843,7 +11843,7 @@ const struct bpf_func_proto bpf_skc_to_unix_sock_proto = {
 BPF_CALL_1(bpf_skc_to_mptcp_sock, struct sock *, sk)
 {
 	BTF_TYPE_EMIT(struct mptcp_sock);
-	return (unsigned long)bpf_mptcp_sock_from_sock(sk);
+	return (unsigned long)bpf_mptcp_sock_from_subflow(sk);
 }
 
 const struct bpf_func_proto bpf_skc_to_mptcp_sock_proto = {

net/mptcp/bpf.c

@@ -195,15 +195,9 @@ static struct bpf_struct_ops bpf_mptcp_sched_ops = {
 };
 #endif /* CONFIG_BPF_JIT */
 
-struct mptcp_sock *bpf_mptcp_sock_from_sock(struct sock *sk)
+struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk)
 {
-	if (unlikely(!sk || !sk_fullsock(sk)))
-		return NULL;
-
-	if (sk->sk_protocol == IPPROTO_MPTCP)
-		return mptcp_sk(sk);
-
-	if (sk->sk_protocol == IPPROTO_TCP && sk_is_mptcp(sk))
+	if (sk && sk_fullsock(sk) && sk->sk_protocol == IPPROTO_TCP && sk_is_mptcp(sk))
 		return mptcp_sk(mptcp_subflow_ctx(sk)->conn);
 
 	return NULL;