Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Plugable TCP congestion control support and newReno |
| 3 | * congestion control. |
Masanari Iida | 02582e9 | 2012-08-22 19:11:26 +0900 | [diff] [blame] | 4 | * Based on ideas from I/O scheduler support and Web100. |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 5 | * |
| 6 | * Copyright (C) 2005 Stephen Hemminger <shemminger@osdl.org> |
| 7 | */ |
| 8 | |
Joe Perches | afd46503 | 2012-03-12 07:03:32 +0000 | [diff] [blame] | 9 | #define pr_fmt(fmt) "TCP: " fmt |
| 10 | |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 11 | #include <linux/module.h> |
| 12 | #include <linux/mm.h> |
| 13 | #include <linux/types.h> |
| 14 | #include <linux/list.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 15 | #include <linux/gfp.h> |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 16 | #include <net/tcp.h> |
| 17 | |
| 18 | static DEFINE_SPINLOCK(tcp_cong_list_lock); |
| 19 | static LIST_HEAD(tcp_cong_list); |
| 20 | |
| 21 | /* Simple linear search, don't expect many entries! */ |
| 22 | static struct tcp_congestion_ops *tcp_ca_find(const char *name) |
| 23 | { |
| 24 | struct tcp_congestion_ops *e; |
| 25 | |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 26 | list_for_each_entry_rcu(e, &tcp_cong_list, list) { |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 27 | if (strcmp(e->name, name) == 0) |
| 28 | return e; |
| 29 | } |
| 30 | |
| 31 | return NULL; |
| 32 | } |
| 33 | |
| 34 | /* |
Robert P. J. Day | d08df60 | 2007-02-17 19:07:33 +0100 | [diff] [blame] | 35 | * Attach new congestion control algorithm to the list |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 36 | * of available options. |
| 37 | */ |
| 38 | int tcp_register_congestion_control(struct tcp_congestion_ops *ca) |
| 39 | { |
| 40 | int ret = 0; |
| 41 | |
| 42 | /* all algorithms must implement ssthresh and cong_avoid ops */ |
Stephen Hemminger | 72dc5b9 | 2006-06-05 17:30:08 -0700 | [diff] [blame] | 43 | if (!ca->ssthresh || !ca->cong_avoid) { |
Joe Perches | afd46503 | 2012-03-12 07:03:32 +0000 | [diff] [blame] | 44 | pr_err("%s does not implement required ops\n", ca->name); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 45 | return -EINVAL; |
| 46 | } |
| 47 | |
| 48 | spin_lock(&tcp_cong_list_lock); |
| 49 | if (tcp_ca_find(ca->name)) { |
Joe Perches | afd46503 | 2012-03-12 07:03:32 +0000 | [diff] [blame] | 50 | pr_notice("%s already registered\n", ca->name); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 51 | ret = -EEXIST; |
| 52 | } else { |
Stephen Hemminger | 3d2573f | 2006-09-24 20:11:58 -0700 | [diff] [blame] | 53 | list_add_tail_rcu(&ca->list, &tcp_cong_list); |
Joe Perches | afd46503 | 2012-03-12 07:03:32 +0000 | [diff] [blame] | 54 | pr_info("%s registered\n", ca->name); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 55 | } |
| 56 | spin_unlock(&tcp_cong_list_lock); |
| 57 | |
| 58 | return ret; |
| 59 | } |
| 60 | EXPORT_SYMBOL_GPL(tcp_register_congestion_control); |
| 61 | |
| 62 | /* |
| 63 | * Remove congestion control algorithm, called from |
| 64 | * the module's remove function. Module ref counts are used |
| 65 | * to ensure that this can't be done till all sockets using |
| 66 | * that method are closed. |
| 67 | */ |
| 68 | void tcp_unregister_congestion_control(struct tcp_congestion_ops *ca) |
| 69 | { |
| 70 | spin_lock(&tcp_cong_list_lock); |
| 71 | list_del_rcu(&ca->list); |
| 72 | spin_unlock(&tcp_cong_list_lock); |
| 73 | } |
| 74 | EXPORT_SYMBOL_GPL(tcp_unregister_congestion_control); |
| 75 | |
| 76 | /* Assign choice of congestion control. */ |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 77 | void tcp_init_congestion_control(struct sock *sk) |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 78 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 79 | struct inet_connection_sock *icsk = inet_csk(sk); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 80 | struct tcp_congestion_ops *ca; |
| 81 | |
Stephen Hemminger | 4d4d3d1 | 2007-04-23 22:32:11 -0700 | [diff] [blame] | 82 | /* if no choice made yet assign the current value set as default */ |
| 83 | if (icsk->icsk_ca_ops == &tcp_init_congestion_ops) { |
| 84 | rcu_read_lock(); |
| 85 | list_for_each_entry_rcu(ca, &tcp_cong_list, list) { |
| 86 | if (try_module_get(ca->owner)) { |
| 87 | icsk->icsk_ca_ops = ca; |
| 88 | break; |
| 89 | } |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 90 | |
Stephen Hemminger | 4d4d3d1 | 2007-04-23 22:32:11 -0700 | [diff] [blame] | 91 | /* fallback to next available */ |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 92 | } |
Stephen Hemminger | 4d4d3d1 | 2007-04-23 22:32:11 -0700 | [diff] [blame] | 93 | rcu_read_unlock(); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 94 | } |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 95 | |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 96 | if (icsk->icsk_ca_ops->init) |
| 97 | icsk->icsk_ca_ops->init(sk); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 98 | } |
| 99 | |
| 100 | /* Manage refcounts on socket close. */ |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 101 | void tcp_cleanup_congestion_control(struct sock *sk) |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 102 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 103 | struct inet_connection_sock *icsk = inet_csk(sk); |
| 104 | |
| 105 | if (icsk->icsk_ca_ops->release) |
| 106 | icsk->icsk_ca_ops->release(sk); |
| 107 | module_put(icsk->icsk_ca_ops->owner); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 108 | } |
| 109 | |
| 110 | /* Used by sysctl to change default congestion control */ |
| 111 | int tcp_set_default_congestion_control(const char *name) |
| 112 | { |
| 113 | struct tcp_congestion_ops *ca; |
| 114 | int ret = -ENOENT; |
| 115 | |
| 116 | spin_lock(&tcp_cong_list_lock); |
| 117 | ca = tcp_ca_find(name); |
Johannes Berg | 95a5afc | 2008-10-16 15:24:51 -0700 | [diff] [blame] | 118 | #ifdef CONFIG_MODULES |
Eric Paris | a8f80e8 | 2009-08-13 09:44:51 -0400 | [diff] [blame] | 119 | if (!ca && capable(CAP_NET_ADMIN)) { |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 120 | spin_unlock(&tcp_cong_list_lock); |
| 121 | |
| 122 | request_module("tcp_%s", name); |
| 123 | spin_lock(&tcp_cong_list_lock); |
| 124 | ca = tcp_ca_find(name); |
| 125 | } |
| 126 | #endif |
| 127 | |
| 128 | if (ca) { |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 129 | ca->flags |= TCP_CONG_NON_RESTRICTED; /* default is always allowed */ |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 130 | list_move(&ca->list, &tcp_cong_list); |
| 131 | ret = 0; |
| 132 | } |
| 133 | spin_unlock(&tcp_cong_list_lock); |
| 134 | |
| 135 | return ret; |
| 136 | } |
| 137 | |
Stephen Hemminger | b1736a7 | 2006-10-31 17:31:33 -0800 | [diff] [blame] | 138 | /* Set default value from kernel configuration at bootup */ |
| 139 | static int __init tcp_congestion_default(void) |
| 140 | { |
| 141 | return tcp_set_default_congestion_control(CONFIG_DEFAULT_TCP_CONG); |
| 142 | } |
| 143 | late_initcall(tcp_congestion_default); |
| 144 | |
Stephen Hemminger | 3ff825b | 2006-11-09 16:32:06 -0800 | [diff] [blame] | 145 | /* Build string with list of available congestion control values */ |
| 146 | void tcp_get_available_congestion_control(char *buf, size_t maxlen) |
| 147 | { |
| 148 | struct tcp_congestion_ops *ca; |
| 149 | size_t offs = 0; |
| 150 | |
| 151 | rcu_read_lock(); |
| 152 | list_for_each_entry_rcu(ca, &tcp_cong_list, list) { |
| 153 | offs += snprintf(buf + offs, maxlen - offs, |
| 154 | "%s%s", |
| 155 | offs == 0 ? "" : " ", ca->name); |
Stephen Hemminger | 3ff825b | 2006-11-09 16:32:06 -0800 | [diff] [blame] | 156 | } |
| 157 | rcu_read_unlock(); |
| 158 | } |
| 159 | |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 160 | /* Get current default congestion control */ |
| 161 | void tcp_get_default_congestion_control(char *name) |
| 162 | { |
| 163 | struct tcp_congestion_ops *ca; |
| 164 | /* We will always have reno... */ |
| 165 | BUG_ON(list_empty(&tcp_cong_list)); |
| 166 | |
| 167 | rcu_read_lock(); |
| 168 | ca = list_entry(tcp_cong_list.next, struct tcp_congestion_ops, list); |
| 169 | strncpy(name, ca->name, TCP_CA_NAME_MAX); |
| 170 | rcu_read_unlock(); |
| 171 | } |
| 172 | |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 173 | /* Built list of non-restricted congestion control values */ |
| 174 | void tcp_get_allowed_congestion_control(char *buf, size_t maxlen) |
| 175 | { |
| 176 | struct tcp_congestion_ops *ca; |
| 177 | size_t offs = 0; |
| 178 | |
| 179 | *buf = '\0'; |
| 180 | rcu_read_lock(); |
| 181 | list_for_each_entry_rcu(ca, &tcp_cong_list, list) { |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 182 | if (!(ca->flags & TCP_CONG_NON_RESTRICTED)) |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 183 | continue; |
| 184 | offs += snprintf(buf + offs, maxlen - offs, |
| 185 | "%s%s", |
| 186 | offs == 0 ? "" : " ", ca->name); |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 187 | } |
| 188 | rcu_read_unlock(); |
| 189 | } |
| 190 | |
| 191 | /* Change list of non-restricted congestion control */ |
| 192 | int tcp_set_allowed_congestion_control(char *val) |
| 193 | { |
| 194 | struct tcp_congestion_ops *ca; |
Julia Lawall | c34186e | 2010-08-27 19:31:56 -0700 | [diff] [blame] | 195 | char *saved_clone, *clone, *name; |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 196 | int ret = 0; |
| 197 | |
Julia Lawall | c34186e | 2010-08-27 19:31:56 -0700 | [diff] [blame] | 198 | saved_clone = clone = kstrdup(val, GFP_USER); |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 199 | if (!clone) |
| 200 | return -ENOMEM; |
| 201 | |
| 202 | spin_lock(&tcp_cong_list_lock); |
| 203 | /* pass 1 check for bad entries */ |
| 204 | while ((name = strsep(&clone, " ")) && *name) { |
| 205 | ca = tcp_ca_find(name); |
| 206 | if (!ca) { |
| 207 | ret = -ENOENT; |
| 208 | goto out; |
| 209 | } |
| 210 | } |
| 211 | |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 212 | /* pass 2 clear old values */ |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 213 | list_for_each_entry_rcu(ca, &tcp_cong_list, list) |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 214 | ca->flags &= ~TCP_CONG_NON_RESTRICTED; |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 215 | |
| 216 | /* pass 3 mark as allowed */ |
| 217 | while ((name = strsep(&val, " ")) && *name) { |
| 218 | ca = tcp_ca_find(name); |
| 219 | WARN_ON(!ca); |
| 220 | if (ca) |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 221 | ca->flags |= TCP_CONG_NON_RESTRICTED; |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 222 | } |
| 223 | out: |
| 224 | spin_unlock(&tcp_cong_list_lock); |
Julia Lawall | c34186e | 2010-08-27 19:31:56 -0700 | [diff] [blame] | 225 | kfree(saved_clone); |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 226 | |
| 227 | return ret; |
| 228 | } |
| 229 | |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 230 | /* Change congestion control for socket */ |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 231 | int tcp_set_congestion_control(struct sock *sk, const char *name) |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 232 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 233 | struct inet_connection_sock *icsk = inet_csk(sk); |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 234 | struct tcp_congestion_ops *ca; |
| 235 | int err = 0; |
| 236 | |
| 237 | rcu_read_lock(); |
| 238 | ca = tcp_ca_find(name); |
Stephen Hemminger | 4d4d3d1 | 2007-04-23 22:32:11 -0700 | [diff] [blame] | 239 | |
Stephen Hemminger | 35bfbc9 | 2006-11-09 16:36:36 -0800 | [diff] [blame] | 240 | /* no change asking for existing value */ |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 241 | if (ca == icsk->icsk_ca_ops) |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 242 | goto out; |
| 243 | |
Johannes Berg | 95a5afc | 2008-10-16 15:24:51 -0700 | [diff] [blame] | 244 | #ifdef CONFIG_MODULES |
Stephen Hemminger | 35bfbc9 | 2006-11-09 16:36:36 -0800 | [diff] [blame] | 245 | /* not found attempt to autoload module */ |
Eric Paris | a8f80e8 | 2009-08-13 09:44:51 -0400 | [diff] [blame] | 246 | if (!ca && capable(CAP_NET_ADMIN)) { |
Stephen Hemminger | 35bfbc9 | 2006-11-09 16:36:36 -0800 | [diff] [blame] | 247 | rcu_read_unlock(); |
| 248 | request_module("tcp_%s", name); |
| 249 | rcu_read_lock(); |
| 250 | ca = tcp_ca_find(name); |
| 251 | } |
| 252 | #endif |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 253 | if (!ca) |
| 254 | err = -ENOENT; |
| 255 | |
Eric W. Biederman | 52e804c | 2012-11-16 03:03:05 +0000 | [diff] [blame] | 256 | else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || |
| 257 | ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))) |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 258 | err = -EPERM; |
| 259 | |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 260 | else if (!try_module_get(ca->owner)) |
| 261 | err = -EBUSY; |
| 262 | |
| 263 | else { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 264 | tcp_cleanup_congestion_control(sk); |
| 265 | icsk->icsk_ca_ops = ca; |
Stephen Hemminger | 4d4d3d1 | 2007-04-23 22:32:11 -0700 | [diff] [blame] | 266 | |
| 267 | if (sk->sk_state != TCP_CLOSE && icsk->icsk_ca_ops->init) |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 268 | icsk->icsk_ca_ops->init(sk); |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 269 | } |
| 270 | out: |
| 271 | rcu_read_unlock(); |
| 272 | return err; |
| 273 | } |
| 274 | |
Yuchung Cheng | 9f9843a7 | 2013-10-31 11:07:31 -0700 | [diff] [blame] | 275 | /* Slow start is used when congestion window is no greater than the slow start |
| 276 | * threshold. We base on RFC2581 and also handle stretch ACKs properly. |
| 277 | * We do not implement RFC3465 Appropriate Byte Counting (ABC) per se but |
| 278 | * something better;) a packet is only considered (s)acked in its entirety to |
| 279 | * defend the ACK attacks described in the RFC. Slow start processes a stretch |
| 280 | * ACK of degree N as if N acks of degree 1 are received back to back except |
| 281 | * ABC caps N to 2. Slow start exits when cwnd grows over ssthresh and |
| 282 | * returns the leftover acks to adjust cwnd in congestion avoidance mode. |
Stephen Hemminger | 40efc6f | 2006-01-03 16:03:49 -0800 | [diff] [blame] | 283 | */ |
Yuchung Cheng | 9f9843a7 | 2013-10-31 11:07:31 -0700 | [diff] [blame] | 284 | int tcp_slow_start(struct tcp_sock *tp, u32 acked) |
Stephen Hemminger | 40efc6f | 2006-01-03 16:03:49 -0800 | [diff] [blame] | 285 | { |
Yuchung Cheng | 9f9843a7 | 2013-10-31 11:07:31 -0700 | [diff] [blame] | 286 | u32 cwnd = tp->snd_cwnd + acked; |
Eric Dumazet | 973ec44 | 2013-02-02 05:23:16 +0000 | [diff] [blame] | 287 | |
Yuchung Cheng | 9f9843a7 | 2013-10-31 11:07:31 -0700 | [diff] [blame] | 288 | if (cwnd > tp->snd_ssthresh) |
| 289 | cwnd = tp->snd_ssthresh + 1; |
| 290 | acked -= cwnd - tp->snd_cwnd; |
| 291 | tp->snd_cwnd = min(cwnd, tp->snd_cwnd_clamp); |
| 292 | return acked; |
Stephen Hemminger | 40efc6f | 2006-01-03 16:03:49 -0800 | [diff] [blame] | 293 | } |
| 294 | EXPORT_SYMBOL_GPL(tcp_slow_start); |
| 295 | |
Ilpo Järvinen | 758ce5c | 2009-02-28 04:44:37 +0000 | [diff] [blame] | 296 | /* In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd (or alternative w) */ |
| 297 | void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w) |
| 298 | { |
| 299 | if (tp->snd_cwnd_cnt >= w) { |
| 300 | if (tp->snd_cwnd < tp->snd_cwnd_clamp) |
| 301 | tp->snd_cwnd++; |
| 302 | tp->snd_cwnd_cnt = 0; |
| 303 | } else { |
| 304 | tp->snd_cwnd_cnt++; |
| 305 | } |
| 306 | } |
| 307 | EXPORT_SYMBOL_GPL(tcp_cong_avoid_ai); |
| 308 | |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 309 | /* |
| 310 | * TCP Reno congestion control |
| 311 | * This is special case used for fallback as well. |
| 312 | */ |
| 313 | /* This is Jacobson's slow start and congestion avoidance. |
| 314 | * SIGCOMM '88, p. 328. |
| 315 | */ |
Eric Dumazet | 2490155 | 2014-05-02 21:18:05 -0700 | [diff] [blame] | 316 | void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked) |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 317 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 318 | struct tcp_sock *tp = tcp_sk(sk); |
| 319 | |
Eric Dumazet | 2490155 | 2014-05-02 21:18:05 -0700 | [diff] [blame] | 320 | if (!tcp_is_cwnd_limited(sk)) |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 321 | return; |
| 322 | |
Stephen Hemminger | 7faffa1 | 2005-11-10 17:07:24 -0800 | [diff] [blame] | 323 | /* In "safe" area, increase. */ |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 324 | if (tp->snd_cwnd <= tp->snd_ssthresh) |
Yuchung Cheng | 9f9843a7 | 2013-10-31 11:07:31 -0700 | [diff] [blame] | 325 | tcp_slow_start(tp, acked); |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 326 | /* In dangerous area, increase slowly. */ |
Stephen Hemminger | ca2eb56 | 2013-02-05 07:25:17 +0000 | [diff] [blame] | 327 | else |
Ilpo Järvinen | 758ce5c | 2009-02-28 04:44:37 +0000 | [diff] [blame] | 328 | tcp_cong_avoid_ai(tp, tp->snd_cwnd); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 329 | } |
| 330 | EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid); |
| 331 | |
| 332 | /* Slow start threshold is half the congestion window (min 2) */ |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 333 | u32 tcp_reno_ssthresh(struct sock *sk) |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 334 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 335 | const struct tcp_sock *tp = tcp_sk(sk); |
stephen hemminger | 688d194 | 2014-08-29 23:32:05 -0700 | [diff] [blame] | 336 | |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 337 | return max(tp->snd_cwnd >> 1U, 2U); |
| 338 | } |
| 339 | EXPORT_SYMBOL_GPL(tcp_reno_ssthresh); |
| 340 | |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 341 | struct tcp_congestion_ops tcp_reno = { |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 342 | .flags = TCP_CONG_NON_RESTRICTED, |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 343 | .name = "reno", |
| 344 | .owner = THIS_MODULE, |
| 345 | .ssthresh = tcp_reno_ssthresh, |
| 346 | .cong_avoid = tcp_reno_cong_avoid, |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 347 | }; |
| 348 | |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 349 | /* Initial congestion control used (until SYN) |
| 350 | * really reno under another name so we can tell difference |
| 351 | * during tcp_set_default_congestion_control |
| 352 | */ |
| 353 | struct tcp_congestion_ops tcp_init_congestion_ops = { |
| 354 | .name = "", |
| 355 | .owner = THIS_MODULE, |
| 356 | .ssthresh = tcp_reno_ssthresh, |
| 357 | .cong_avoid = tcp_reno_cong_avoid, |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 358 | }; |
| 359 | EXPORT_SYMBOL_GPL(tcp_init_congestion_ops); |