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 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 */ 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 54 /* Build string with list of available scheduler values. 55 * Similar to tcp_get_available_congestion_control() 56 */ 57 void mptcp_get_available_schedulers(char *buf, size_t maxlen) 58 { 59 struct mptcp_sched_ops *sched; 60 size_t offs = 0; 61 62 rcu_read_lock(); 63 spin_lock(&mptcp_sched_list_lock); 64 list_for_each_entry_rcu(sched, &mptcp_sched_list, list) { 65 offs += snprintf(buf + offs, maxlen - offs, 66 "%s%s", 67 offs == 0 ? "" : " ", sched->name); 68 69 if (WARN_ON_ONCE(offs >= maxlen)) 70 break; 71 } 72 spin_unlock(&mptcp_sched_list_lock); 73 rcu_read_unlock(); 74 } 75 76 int mptcp_register_scheduler(struct mptcp_sched_ops *sched) 77 { 78 if (!sched->get_subflow) 79 return -EINVAL; 80 81 spin_lock(&mptcp_sched_list_lock); 82 if (mptcp_sched_find(sched->name)) { 83 spin_unlock(&mptcp_sched_list_lock); 84 return -EEXIST; 85 } 86 list_add_tail_rcu(&sched->list, &mptcp_sched_list); 87 spin_unlock(&mptcp_sched_list_lock); 88 89 pr_debug("%s registered\n", sched->name); 90 return 0; 91 } 92 93 void mptcp_unregister_scheduler(struct mptcp_sched_ops *sched) 94 { 95 if (sched == &mptcp_sched_default) 96 return; 97 98 spin_lock(&mptcp_sched_list_lock); 99 list_del_rcu(&sched->list); 100 spin_unlock(&mptcp_sched_list_lock); 101 } 102 103 void mptcp_sched_init(void) 104 { 105 mptcp_register_scheduler(&mptcp_sched_default); 106 } 107 108 int mptcp_init_sched(struct mptcp_sock *msk, 109 struct mptcp_sched_ops *sched) 110 { 111 if (!sched) 112 sched = &mptcp_sched_default; 113 114 if (!bpf_try_module_get(sched, sched->owner)) 115 return -EBUSY; 116 117 msk->sched = sched; 118 if (msk->sched->init) 119 msk->sched->init(msk); 120 121 pr_debug("sched=%s\n", msk->sched->name); 122 123 return 0; 124 } 125 126 void mptcp_release_sched(struct mptcp_sock *msk) 127 { 128 struct mptcp_sched_ops *sched = msk->sched; 129 130 if (!sched) 131 return; 132 133 msk->sched = NULL; 134 if (sched->release) 135 sched->release(msk); 136 137 bpf_module_put(sched, sched->owner); 138 } 139 140 void mptcp_subflow_set_scheduled(struct mptcp_subflow_context *subflow, 141 bool scheduled) 142 { 143 WRITE_ONCE(subflow->scheduled, scheduled); 144 } 145 146 int mptcp_sched_get_send(struct mptcp_sock *msk) 147 { 148 struct mptcp_subflow_context *subflow; 149 struct mptcp_sched_data data; 150 151 msk_owned_by_me(msk); 152 153 /* the following check is moved out of mptcp_subflow_get_send */ 154 if (__mptcp_check_fallback(msk)) { 155 if (msk->first && 156 __tcp_can_send(msk->first) && 157 sk_stream_memory_free(msk->first)) { 158 mptcp_subflow_set_scheduled(mptcp_subflow_ctx(msk->first), true); 159 return 0; 160 } 161 return -EINVAL; 162 } 163 164 mptcp_for_each_subflow(msk, subflow) { 165 if (READ_ONCE(subflow->scheduled)) 166 return 0; 167 } 168 169 data.reinject = false; 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 } 174 175 int mptcp_sched_get_retrans(struct mptcp_sock *msk) 176 { 177 struct mptcp_subflow_context *subflow; 178 struct mptcp_sched_data data; 179 180 msk_owned_by_me(msk); 181 182 /* the following check is moved out of mptcp_subflow_get_retrans */ 183 if (__mptcp_check_fallback(msk)) 184 return -EINVAL; 185 186 mptcp_for_each_subflow(msk, subflow) { 187 if (READ_ONCE(subflow->scheduled)) 188 return 0; 189 } 190 191 data.reinject = true; 192 if (msk->sched == &mptcp_sched_default || !msk->sched) 193 return mptcp_sched_default_get_subflow(msk, &data); 194 return msk->sched->get_subflow(msk, &data); 195 } 196