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 list_for_each_entry_rcu(sched, &mptcp_sched_list, list) { 64 offs += snprintf(buf + offs, maxlen - offs, 65 "%s%s", 66 offs == 0 ? "" : " ", sched->name); 67 68 if (WARN_ON_ONCE(offs >= maxlen)) 69 break; 70 } 71 rcu_read_unlock(); 72 } 73 74 int mptcp_register_scheduler(struct mptcp_sched_ops *sched) 75 { 76 if (!sched->get_subflow) 77 return -EINVAL; 78 79 spin_lock(&mptcp_sched_list_lock); 80 if (mptcp_sched_find(sched->name)) { 81 spin_unlock(&mptcp_sched_list_lock); 82 return -EEXIST; 83 } 84 list_add_tail_rcu(&sched->list, &mptcp_sched_list); 85 spin_unlock(&mptcp_sched_list_lock); 86 87 pr_debug("%s registered\n", sched->name); 88 return 0; 89 } 90 91 void mptcp_unregister_scheduler(struct mptcp_sched_ops *sched) 92 { 93 if (sched == &mptcp_sched_default) 94 return; 95 96 spin_lock(&mptcp_sched_list_lock); 97 list_del_rcu(&sched->list); 98 spin_unlock(&mptcp_sched_list_lock); 99 } 100 101 void mptcp_sched_init(void) 102 { 103 mptcp_register_scheduler(&mptcp_sched_default); 104 } 105 106 int mptcp_init_sched(struct mptcp_sock *msk, 107 struct mptcp_sched_ops *sched) 108 { 109 if (!sched) 110 sched = &mptcp_sched_default; 111 112 if (!bpf_try_module_get(sched, sched->owner)) 113 return -EBUSY; 114 115 msk->sched = sched; 116 if (msk->sched->init) 117 msk->sched->init(msk); 118 119 pr_debug("sched=%s\n", msk->sched->name); 120 121 return 0; 122 } 123 124 void mptcp_release_sched(struct mptcp_sock *msk) 125 { 126 struct mptcp_sched_ops *sched = msk->sched; 127 128 if (!sched) 129 return; 130 131 msk->sched = NULL; 132 if (sched->release) 133 sched->release(msk); 134 135 bpf_module_put(sched, sched->owner); 136 } 137 138 void mptcp_subflow_set_scheduled(struct mptcp_subflow_context *subflow, 139 bool scheduled) 140 { 141 WRITE_ONCE(subflow->scheduled, scheduled); 142 } 143 144 int mptcp_sched_get_send(struct mptcp_sock *msk) 145 { 146 struct mptcp_subflow_context *subflow; 147 struct mptcp_sched_data data; 148 149 msk_owned_by_me(msk); 150 151 /* the following check is moved out of mptcp_subflow_get_send */ 152 if (__mptcp_check_fallback(msk)) { 153 if (msk->first && 154 __tcp_can_send(msk->first) && 155 sk_stream_memory_free(msk->first)) { 156 mptcp_subflow_set_scheduled(mptcp_subflow_ctx(msk->first), true); 157 return 0; 158 } 159 return -EINVAL; 160 } 161 162 mptcp_for_each_subflow(msk, subflow) { 163 if (READ_ONCE(subflow->scheduled)) 164 return 0; 165 } 166 167 data.reinject = false; 168 if (msk->sched == &mptcp_sched_default || !msk->sched) 169 return mptcp_sched_default_get_subflow(msk, &data); 170 return msk->sched->get_subflow(msk, &data); 171 } 172 173 int mptcp_sched_get_retrans(struct mptcp_sock *msk) 174 { 175 struct mptcp_subflow_context *subflow; 176 struct mptcp_sched_data data; 177 178 msk_owned_by_me(msk); 179 180 /* the following check is moved out of mptcp_subflow_get_retrans */ 181 if (__mptcp_check_fallback(msk)) 182 return -EINVAL; 183 184 mptcp_for_each_subflow(msk, subflow) { 185 if (READ_ONCE(subflow->scheduled)) 186 return 0; 187 } 188 189 data.reinject = true; 190 if (msk->sched == &mptcp_sched_default || !msk->sched) 191 return mptcp_sched_default_get_subflow(msk, &data); 192 return msk->sched->get_subflow(msk, &data); 193 } 194