Squash to "bpf: Export mptcp packet scheduler helpers"

Define .filter as Martin suggested.

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

Author: Geliang Tang

net/mptcp/bpf.c

@@ -317,18 +317,37 @@ BTF_ID_FLAGS(func, bpf_mptcp_subflow_queues_empty)
 BTF_ID_FLAGS(func, mptcp_pm_subflow_chk_stale, KF_SLEEPABLE)
 BTF_KFUNCS_END(bpf_mptcp_common_kfunc_ids)
 
+static int bpf_mptcp_common_kfunc_filter(const struct bpf_prog *prog, u32 kfunc_id)
+{
+	if (!btf_id_set8_contains(&bpf_mptcp_common_kfunc_ids, kfunc_id))
+		return 0;
+
+	if (prog->type != BPF_PROG_TYPE_STRUCT_OPS)
+		return -EACCES;
+
+	/* .filter is called sometimes before prog->aux->st_ops is set,
+	 * then prog->aux->st_ops is NULL. If return -EACCES in this case,
+	 * an error occur:
+	 * 	bug: bad parent state for iter next call
+	 */
+	if (prog->aux->st_ops &&
+	    prog->aux->st_ops != &bpf_mptcp_sched_ops)
+		return -EACCES;
+
+	return 0;
+}
+
 static const struct btf_kfunc_id_set bpf_mptcp_common_kfunc_set = {
 	.owner	= THIS_MODULE,
 	.set	= &bpf_mptcp_common_kfunc_ids,
+	.filter	= bpf_mptcp_common_kfunc_filter,
 };
 
 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_CGROUP_SOCKOPT,
-					       &bpf_mptcp_common_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS,
 					       &bpf_mptcp_common_kfunc_set);
 #ifdef CONFIG_BPF_JIT