From: Geliang Tang <tanggeliang@kylinos.cn>

bpf_mptcp_sk() definition is missing. It will be used in patch 4.

Please update the commit log:

'''
MPTCP helper mptcp_sk() is used to convert struct sock to mptcp_sock.
Helpers mptcp_subflow_ctx() and mptcp_subflow_tcp_sock() are used to
convert between struct mptcp_subflow_context and sock. They all will
be used in MPTCP BPF programs too. This patch defines corresponding
wrappers of them, and put the wrappers into mptcp common kfunc set
and register the set with the flag BPF_PROG_TYPE_UNSPEC to let them
accessible to all types of BPF programs.
'''

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 net/mptcp/bpf.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/mptcp/bpf.c b/net/mptcp/bpf.c
index a2fd62c2777a..1ad7f703abb2 100644
--- a/net/mptcp/bpf.c
+++ b/net/mptcp/bpf.c
@@ -216,6 +216,11 @@ struct bpf_iter_mptcp_subflow_kern {
 
 __bpf_kfunc_start_defs();
 
+__bpf_kfunc static struct mptcp_sock *bpf_mptcp_sk(struct sock *sk)
+{
+	return mptcp_sk(sk);
+}
+
 __bpf_kfunc static struct mptcp_subflow_context *
 bpf_mptcp_subflow_ctx(const struct sock *sk)
 {
@@ -291,6 +296,7 @@ __bpf_kfunc static bool bpf_mptcp_subflow_queues_empty(struct sock *sk)
 __bpf_kfunc_end_defs();
 
 BTF_KFUNCS_START(bpf_mptcp_common_kfunc_ids)
+BTF_ID_FLAGS(func, bpf_mptcp_sk)
 BTF_ID_FLAGS(func, bpf_mptcp_subflow_ctx)
 BTF_ID_FLAGS(func, bpf_mptcp_subflow_tcp_sock)
 BTF_ID_FLAGS(func, bpf_iter_mptcp_subflow_new, KF_ITER_NEW | KF_TRUSTED_ARGS)
-- 
2.43.0