From: Geliang Tang <tanggeliang@kylinos.cn>

Helpers mptcp_subflow_ctx() and mptcp_subflow_tcp_sock() are useful in
MPTCP BPF programs. This patch defines corresponding wrappers of them,
and put the wrappers into mptcp common kfunc set and register the set
with BPF_PROG_TYPE_UNSPEC.

Two other kfuncs mptcp_subflow_active() and mptcp_subflow_set_scheduled()
are going to be used in mptcp_subflow bpf_iter selftest, put them into
mptcp common kfunc set too.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 net/mptcp/bpf.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/bpf.c b/net/mptcp/bpf.c
index 6414824402e6..71ab1efeed40 100644
--- a/net/mptcp/bpf.c
+++ b/net/mptcp/bpf.c
@@ -205,6 +205,18 @@ __diag_push();
 __diag_ignore_all("-Wmissing-prototypes",
 		  "kfuncs which will be used in BPF programs");
 
+__bpf_kfunc struct mptcp_subflow_context *
+bpf_mptcp_subflow_ctx(const struct sock *sk)
+{
+	return mptcp_subflow_ctx(sk);
+}
+
+__bpf_kfunc struct sock *
+bpf_mptcp_subflow_tcp_sock(const struct mptcp_subflow_context *subflow)
+{
+	return mptcp_subflow_tcp_sock(subflow);
+}
+
 __bpf_kfunc struct mptcp_subflow_context *
 bpf_mptcp_subflow_ctx_by_pos(const struct mptcp_sched_data *data, unsigned int pos)
 {
@@ -220,10 +232,20 @@ __bpf_kfunc bool bpf_mptcp_subflow_queues_empty(struct sock *sk)
 
 __diag_pop();
 
-BTF_KFUNCS_START(bpf_mptcp_sched_kfunc_ids)
+BTF_KFUNCS_START(bpf_mptcp_common_kfunc_ids)
+BTF_ID_FLAGS(func, bpf_mptcp_subflow_ctx)
+BTF_ID_FLAGS(func, bpf_mptcp_subflow_tcp_sock)
 BTF_ID_FLAGS(func, mptcp_subflow_set_scheduled)
-BTF_ID_FLAGS(func, bpf_mptcp_subflow_ctx_by_pos)
 BTF_ID_FLAGS(func, mptcp_subflow_active)
+BTF_KFUNCS_END(bpf_mptcp_common_kfunc_ids)
+
+static const struct btf_kfunc_id_set bpf_mptcp_common_kfunc_set = {
+	.owner	= THIS_MODULE,
+	.set	= &bpf_mptcp_common_kfunc_ids,
+};
+
+BTF_KFUNCS_START(bpf_mptcp_sched_kfunc_ids)
+BTF_ID_FLAGS(func, bpf_mptcp_subflow_ctx_by_pos)
 BTF_ID_FLAGS(func, mptcp_set_timeout)
 BTF_ID_FLAGS(func, mptcp_wnd_end)
 BTF_ID_FLAGS(func, tcp_stream_memory_free)
@@ -241,6 +263,8 @@ static int __init bpf_mptcp_kfunc_init(void)
 	int ret;
 
 	ret = register_btf_fmodret_id_set(&bpf_mptcp_fmodret_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_UNSPEC,
+					       &bpf_mptcp_common_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS,
 					       &bpf_mptcp_sched_kfunc_set);
 #ifdef CONFIG_BPF_JIT
-- 
2.43.0