bpf: Export mptcp packet scheduler helpers

This patch adds a new struct btf_kfunc_id_set for MPTCP scheduler. Add
mptcp_subflow_set_scheduled() and mptcp_sched_data_set_contexts() helpers
into this id_set, and register it in bpf_mptcp_kfunc_init() to make sure
these helpers can be accessed from the BPF context.

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

Author: Geliang Tang

net/mptcp/bpf.c

@@ -219,6 +219,27 @@ struct bpf_iter_mptcp_subflow_kern {
 
 __bpf_kfunc_start_defs();
 
+__bpf_kfunc static struct mptcp_subflow_context *
+bpf_mptcp_subflow_ctx(const struct sock *sk__ign)
+{
+	const struct sock *sk = sk__ign;
+
+	if (sk && sk_fullsock(sk) &&
+	    sk->sk_protocol == IPPROTO_TCP && sk_is_mptcp(sk))
+		return mptcp_subflow_ctx(sk);
+
+	return NULL;
+}
+
+__bpf_kfunc static struct sock *
+bpf_mptcp_subflow_tcp_sock(const struct mptcp_subflow_context *subflow)
+{
+	if (!subflow)
+		return NULL;
+
+	return mptcp_subflow_tcp_sock(subflow);
+}
+
 __bpf_kfunc static int
 bpf_iter_mptcp_subflow_new(struct bpf_iter_mptcp_subflow *it,
 			   struct sock *sk)
@@ -263,6 +284,22 @@ bpf_iter_mptcp_subflow_destroy(struct bpf_iter_mptcp_subflow *it)
 {
 }
 
+__bpf_kfunc static bool bpf_mptcp_subflow_queues_empty(struct sock *sk)
+{
+	return tcp_rtx_queue_empty(sk);
+}
+
+__bpf_kfunc static bool bpf_sk_stream_memory_free(const struct sock *sk__ign)
+{
+	const struct sock *sk = sk__ign;
+
+	if (sk && sk_fullsock(sk) &&
+	    sk->sk_protocol == IPPROTO_TCP && sk_is_mptcp(sk))
+		return sk_stream_memory_free(sk);
+
+	return NULL;
+}
+
 __bpf_kfunc_end_defs();
 
 BTF_KFUNCS_START(bpf_mptcp_iter_kfunc_ids)
@@ -276,13 +313,48 @@ static const struct btf_kfunc_id_set bpf_mptcp_iter_kfunc_set = {
 	.set	= &bpf_mptcp_iter_kfunc_ids,
 };
 
+BTF_KFUNCS_START(bpf_mptcp_common_kfunc_ids)
+BTF_ID_FLAGS(func, bpf_mptcp_subflow_ctx, KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_mptcp_subflow_tcp_sock, KF_RET_NULL)
+BTF_ID_FLAGS(func, mptcp_subflow_set_scheduled)
+BTF_ID_FLAGS(func, mptcp_subflow_active)
+BTF_ID_FLAGS(func, mptcp_set_timeout)
+BTF_ID_FLAGS(func, mptcp_wnd_end)
+BTF_ID_FLAGS(func, bpf_sk_stream_memory_free, KF_RET_NULL)
+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;
+
+#ifdef CONFIG_BPF_JIT
+	if (prog->aux->st_ops == &bpf_mptcp_sched_ops)
+		return 0;
+#endif
+	return -EACCES;
+}
+
+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_STRUCT_OPS,
 					       &bpf_mptcp_iter_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS,
+					       &bpf_mptcp_common_kfunc_set);
 #ifdef CONFIG_BPF_JIT
 	ret = ret ?: register_bpf_struct_ops(&bpf_mptcp_sched_ops, mptcp_sched_ops);
 #endif

net/mptcp/protocol.c

@@ -53,7 +53,7 @@ DEFINE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions) = {
 static struct net_device *mptcp_napi_dev;
 
 /* Returns end sequence number of the receiver's advertised window */
-static u64 mptcp_wnd_end(const struct mptcp_sock *msk)
+u64 mptcp_wnd_end(const struct mptcp_sock *msk)
 {
 	return READ_ONCE(msk->wnd_end);
 }
@@ -448,7 +448,7 @@ static long mptcp_timeout_from_subflow(const struct mptcp_subflow_context *subfl
 	       icsk_timeout(inet_csk(ssk)) - jiffies : 0;
 }
 
-static void mptcp_set_timeout(struct sock *sk)
+void mptcp_set_timeout(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow;
 	long tout = 0;

net/mptcp/protocol.h

@@ -737,6 +737,8 @@ void __mptcp_subflow_send_ack(struct sock *ssk);
 void mptcp_subflow_reset(struct sock *ssk);
 void mptcp_subflow_queue_clean(struct sock *sk, struct sock *ssk);
 void mptcp_sock_graft(struct sock *sk, struct socket *parent);
+u64 mptcp_wnd_end(const struct mptcp_sock *msk);
+void mptcp_set_timeout(struct sock *sk);
 struct sock *__mptcp_nmpc_sk(struct mptcp_sock *msk);
 bool __mptcp_close(struct sock *sk, long timeout);
 void mptcp_cancel_work(struct sock *sk);