1 // SPDX-License-Identifier: GPL-2.0
2 /* Multipath TCP
3 *
4 * Copyright (c) 2022, SUSE.
5 */
6
7 #define pr_fmt(fmt) "MPTCP: " fmt
8
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/list.h>
12 #include <linux/rculist.h>
13 #include <linux/spinlock.h>
14 #include "protocol.h"
15
16 static DEFINE_SPINLOCK(mptcp_sched_list_lock);
17 static LIST_HEAD(mptcp_sched_list);
18
mptcp_sched_default_get_subflow(struct mptcp_sock * msk,struct mptcp_sched_data * data)19 static int mptcp_sched_default_get_subflow(struct mptcp_sock *msk,
20 struct mptcp_sched_data *data)
21 {
22 struct sock *ssk;
23
24 ssk = data->reinject ? mptcp_subflow_get_retrans(msk) :
25 mptcp_subflow_get_send(msk);
26 if (!ssk)
27 return -EINVAL;
28
29 mptcp_subflow_set_scheduled(mptcp_subflow_ctx(ssk), true);
30 return 0;
31 }
32
33 static struct mptcp_sched_ops mptcp_sched_default = {
34 .get_subflow = mptcp_sched_default_get_subflow,
35 .name = "default",
36 .owner = THIS_MODULE,
37 };
38
39 /* Must be called with rcu read lock held */
mptcp_sched_find(const char * name)40 struct mptcp_sched_ops *mptcp_sched_find(const char *name)
41 {
42 struct mptcp_sched_ops *sched, *ret = NULL;
43
44 list_for_each_entry_rcu(sched, &mptcp_sched_list, list) {
45 if (!strcmp(sched->name, name)) {
46 ret = sched;
47 break;
48 }
49 }
50
51 return ret;
52 }
53
mptcp_register_scheduler(struct mptcp_sched_ops * sched)54 int mptcp_register_scheduler(struct mptcp_sched_ops *sched)
55 {
56 if (!sched->get_subflow)
57 return -EINVAL;
58
59 spin_lock(&mptcp_sched_list_lock);
60 if (mptcp_sched_find(sched->name)) {
61 spin_unlock(&mptcp_sched_list_lock);
62 return -EEXIST;
63 }
64 list_add_tail_rcu(&sched->list, &mptcp_sched_list);
65 spin_unlock(&mptcp_sched_list_lock);
66
67 pr_debug("%s registered", sched->name);
68 return 0;
69 }
70
mptcp_unregister_scheduler(struct mptcp_sched_ops * sched)71 void mptcp_unregister_scheduler(struct mptcp_sched_ops *sched)
72 {
73 if (sched == &mptcp_sched_default)
74 return;
75
76 spin_lock(&mptcp_sched_list_lock);
77 list_del_rcu(&sched->list);
78 spin_unlock(&mptcp_sched_list_lock);
79 }
80
mptcp_sched_init(void)81 void mptcp_sched_init(void)
82 {
83 mptcp_register_scheduler(&mptcp_sched_default);
84 }
85
mptcp_init_sched(struct mptcp_sock * msk,struct mptcp_sched_ops * sched)86 int mptcp_init_sched(struct mptcp_sock *msk,
87 struct mptcp_sched_ops *sched)
88 {
89 if (!sched)
90 sched = &mptcp_sched_default;
91
92 if (!bpf_try_module_get(sched, sched->owner))
93 return -EBUSY;
94
95 msk->sched = sched;
96 if (msk->sched->init)
97 msk->sched->init(msk);
98
99 pr_debug("sched=%s", msk->sched->name);
100
101 return 0;
102 }
103
mptcp_release_sched(struct mptcp_sock * msk)104 void mptcp_release_sched(struct mptcp_sock *msk)
105 {
106 struct mptcp_sched_ops *sched = msk->sched;
107
108 if (!sched)
109 return;
110
111 msk->sched = NULL;
112 if (sched->release)
113 sched->release(msk);
114
115 bpf_module_put(sched, sched->owner);
116 }
117
mptcp_subflow_set_scheduled(struct mptcp_subflow_context * subflow,bool scheduled)118 void mptcp_subflow_set_scheduled(struct mptcp_subflow_context *subflow,
119 bool scheduled)
120 {
121 WRITE_ONCE(subflow->scheduled, scheduled);
122 }
123
mptcp_sched_get_send(struct mptcp_sock * msk)124 int mptcp_sched_get_send(struct mptcp_sock *msk)
125 {
126 struct mptcp_subflow_context *subflow;
127 struct mptcp_sched_data data;
128
129 msk_owned_by_me(msk);
130
131 /* the following check is moved out of mptcp_subflow_get_send */
132 if (__mptcp_check_fallback(msk)) {
133 if (msk->first &&
134 __tcp_can_send(msk->first) &&
135 sk_stream_memory_free(msk->first)) {
136 mptcp_subflow_set_scheduled(mptcp_subflow_ctx(msk->first), true);
137 return 0;
138 }
139 return -EINVAL;
140 }
141
142 mptcp_for_each_subflow(msk, subflow) {
143 if (READ_ONCE(subflow->scheduled))
144 return 0;
145 }
146
147 data.reinject = false;
148 if (msk->sched == &mptcp_sched_default || !msk->sched)
149 return mptcp_sched_default_get_subflow(msk, &data);
150 return msk->sched->get_subflow(msk, &data);
151 }
152
mptcp_sched_get_retrans(struct mptcp_sock * msk)153 int mptcp_sched_get_retrans(struct mptcp_sock *msk)
154 {
155 struct mptcp_subflow_context *subflow;
156 struct mptcp_sched_data data;
157
158 msk_owned_by_me(msk);
159
160 /* the following check is moved out of mptcp_subflow_get_retrans */
161 if (__mptcp_check_fallback(msk))
162 return -EINVAL;
163
164 mptcp_for_each_subflow(msk, subflow) {
165 if (READ_ONCE(subflow->scheduled))
166 return 0;
167 }
168
169 data.reinject = true;
170 if (msk->sched == &mptcp_sched_default || !msk->sched)
171 return mptcp_sched_default_get_subflow(msk, &data);
172 return msk->sched->get_subflow(msk, &data);
173 }
174
