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 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\n", sched->name); 68 return 0; 69 } 70 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 81 void mptcp_sched_init(void) 82 { 83 mptcp_register_scheduler(&mptcp_sched_default); 84 } 85 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\n", msk->sched->name); 100 101 return 0; 102 } 103 104 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 } 117 118 void mptcp_subflow_set_scheduled(struct mptcp_subflow_context *subflow, 119 bool scheduled) 120 { 121 WRITE_ONCE(subflow->scheduled, scheduled); 122 } 123 124 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 } 152 153 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