diff options
author | 2015-08-04 12:17:53 -0700 | |
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committer | 2015-08-04 15:44:42 -0700 | |
commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/net/ipv4/tcp_cong.c | |
parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/net/ipv4/tcp_cong.c')
-rw-r--r-- | kernel/net/ipv4/tcp_cong.c | 441 |
1 files changed, 441 insertions, 0 deletions
diff --git a/kernel/net/ipv4/tcp_cong.c b/kernel/net/ipv4/tcp_cong.c new file mode 100644 index 000000000..84be008c9 --- /dev/null +++ b/kernel/net/ipv4/tcp_cong.c @@ -0,0 +1,441 @@ +/* + * Pluggable TCP congestion control support and newReno + * congestion control. + * Based on ideas from I/O scheduler support and Web100. + * + * Copyright (C) 2005 Stephen Hemminger <shemminger@osdl.org> + */ + +#define pr_fmt(fmt) "TCP: " fmt + +#include <linux/module.h> +#include <linux/mm.h> +#include <linux/types.h> +#include <linux/list.h> +#include <linux/gfp.h> +#include <linux/jhash.h> +#include <net/tcp.h> + +static DEFINE_SPINLOCK(tcp_cong_list_lock); +static LIST_HEAD(tcp_cong_list); + +/* Simple linear search, don't expect many entries! */ +static struct tcp_congestion_ops *tcp_ca_find(const char *name) +{ + struct tcp_congestion_ops *e; + + list_for_each_entry_rcu(e, &tcp_cong_list, list) { + if (strcmp(e->name, name) == 0) + return e; + } + + return NULL; +} + +/* Must be called with rcu lock held */ +static const struct tcp_congestion_ops *__tcp_ca_find_autoload(const char *name) +{ + const struct tcp_congestion_ops *ca = tcp_ca_find(name); +#ifdef CONFIG_MODULES + if (!ca && capable(CAP_NET_ADMIN)) { + rcu_read_unlock(); + request_module("tcp_%s", name); + rcu_read_lock(); + ca = tcp_ca_find(name); + } +#endif + return ca; +} + +/* Simple linear search, not much in here. */ +struct tcp_congestion_ops *tcp_ca_find_key(u32 key) +{ + struct tcp_congestion_ops *e; + + list_for_each_entry_rcu(e, &tcp_cong_list, list) { + if (e->key == key) + return e; + } + + return NULL; +} + +/* + * Attach new congestion control algorithm to the list + * of available options. + */ +int tcp_register_congestion_control(struct tcp_congestion_ops *ca) +{ + int ret = 0; + + /* all algorithms must implement ssthresh and cong_avoid ops */ + if (!ca->ssthresh || !ca->cong_avoid) { + pr_err("%s does not implement required ops\n", ca->name); + return -EINVAL; + } + + ca->key = jhash(ca->name, sizeof(ca->name), strlen(ca->name)); + + spin_lock(&tcp_cong_list_lock); + if (ca->key == TCP_CA_UNSPEC || tcp_ca_find_key(ca->key)) { + pr_notice("%s already registered or non-unique key\n", + ca->name); + ret = -EEXIST; + } else { + list_add_tail_rcu(&ca->list, &tcp_cong_list); + pr_debug("%s registered\n", ca->name); + } + spin_unlock(&tcp_cong_list_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(tcp_register_congestion_control); + +/* + * Remove congestion control algorithm, called from + * the module's remove function. Module ref counts are used + * to ensure that this can't be done till all sockets using + * that method are closed. + */ +void tcp_unregister_congestion_control(struct tcp_congestion_ops *ca) +{ + spin_lock(&tcp_cong_list_lock); + list_del_rcu(&ca->list); + spin_unlock(&tcp_cong_list_lock); + + /* Wait for outstanding readers to complete before the + * module gets removed entirely. + * + * A try_module_get() should fail by now as our module is + * in "going" state since no refs are held anymore and + * module_exit() handler being called. + */ + synchronize_rcu(); +} +EXPORT_SYMBOL_GPL(tcp_unregister_congestion_control); + +u32 tcp_ca_get_key_by_name(const char *name) +{ + const struct tcp_congestion_ops *ca; + u32 key; + + might_sleep(); + + rcu_read_lock(); + ca = __tcp_ca_find_autoload(name); + key = ca ? ca->key : TCP_CA_UNSPEC; + rcu_read_unlock(); + + return key; +} +EXPORT_SYMBOL_GPL(tcp_ca_get_key_by_name); + +char *tcp_ca_get_name_by_key(u32 key, char *buffer) +{ + const struct tcp_congestion_ops *ca; + char *ret = NULL; + + rcu_read_lock(); + ca = tcp_ca_find_key(key); + if (ca) + ret = strncpy(buffer, ca->name, + TCP_CA_NAME_MAX); + rcu_read_unlock(); + + return ret; +} +EXPORT_SYMBOL_GPL(tcp_ca_get_name_by_key); + +/* Assign choice of congestion control. */ +void tcp_assign_congestion_control(struct sock *sk) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + struct tcp_congestion_ops *ca; + + rcu_read_lock(); + list_for_each_entry_rcu(ca, &tcp_cong_list, list) { + if (likely(try_module_get(ca->owner))) { + icsk->icsk_ca_ops = ca; + goto out; + } + /* Fallback to next available. The last really + * guaranteed fallback is Reno from this list. + */ + } +out: + rcu_read_unlock(); + + /* Clear out private data before diag gets it and + * the ca has not been initialized. + */ + if (ca->get_info) + memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv)); +} + +void tcp_init_congestion_control(struct sock *sk) +{ + const struct inet_connection_sock *icsk = inet_csk(sk); + + if (icsk->icsk_ca_ops->init) + icsk->icsk_ca_ops->init(sk); +} + +static void tcp_reinit_congestion_control(struct sock *sk, + const struct tcp_congestion_ops *ca) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + + tcp_cleanup_congestion_control(sk); + icsk->icsk_ca_ops = ca; + icsk->icsk_ca_setsockopt = 1; + + if (sk->sk_state != TCP_CLOSE && icsk->icsk_ca_ops->init) + icsk->icsk_ca_ops->init(sk); +} + +/* Manage refcounts on socket close. */ +void tcp_cleanup_congestion_control(struct sock *sk) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + + if (icsk->icsk_ca_ops->release) + icsk->icsk_ca_ops->release(sk); + module_put(icsk->icsk_ca_ops->owner); +} + +/* Used by sysctl to change default congestion control */ +int tcp_set_default_congestion_control(const char *name) +{ + struct tcp_congestion_ops *ca; + int ret = -ENOENT; + + spin_lock(&tcp_cong_list_lock); + ca = tcp_ca_find(name); +#ifdef CONFIG_MODULES + if (!ca && capable(CAP_NET_ADMIN)) { + spin_unlock(&tcp_cong_list_lock); + + request_module("tcp_%s", name); + spin_lock(&tcp_cong_list_lock); + ca = tcp_ca_find(name); + } +#endif + + if (ca) { + ca->flags |= TCP_CONG_NON_RESTRICTED; /* default is always allowed */ + list_move(&ca->list, &tcp_cong_list); + ret = 0; + } + spin_unlock(&tcp_cong_list_lock); + + return ret; +} + +/* Set default value from kernel configuration at bootup */ +static int __init tcp_congestion_default(void) +{ + return tcp_set_default_congestion_control(CONFIG_DEFAULT_TCP_CONG); +} +late_initcall(tcp_congestion_default); + +/* Build string with list of available congestion control values */ +void tcp_get_available_congestion_control(char *buf, size_t maxlen) +{ + struct tcp_congestion_ops *ca; + size_t offs = 0; + + rcu_read_lock(); + list_for_each_entry_rcu(ca, &tcp_cong_list, list) { + offs += snprintf(buf + offs, maxlen - offs, + "%s%s", + offs == 0 ? "" : " ", ca->name); + } + rcu_read_unlock(); +} + +/* Get current default congestion control */ +void tcp_get_default_congestion_control(char *name) +{ + struct tcp_congestion_ops *ca; + /* We will always have reno... */ + BUG_ON(list_empty(&tcp_cong_list)); + + rcu_read_lock(); + ca = list_entry(tcp_cong_list.next, struct tcp_congestion_ops, list); + strncpy(name, ca->name, TCP_CA_NAME_MAX); + rcu_read_unlock(); +} + +/* Built list of non-restricted congestion control values */ +void tcp_get_allowed_congestion_control(char *buf, size_t maxlen) +{ + struct tcp_congestion_ops *ca; + size_t offs = 0; + + *buf = '\0'; + rcu_read_lock(); + list_for_each_entry_rcu(ca, &tcp_cong_list, list) { + if (!(ca->flags & TCP_CONG_NON_RESTRICTED)) + continue; + offs += snprintf(buf + offs, maxlen - offs, + "%s%s", + offs == 0 ? "" : " ", ca->name); + } + rcu_read_unlock(); +} + +/* Change list of non-restricted congestion control */ +int tcp_set_allowed_congestion_control(char *val) +{ + struct tcp_congestion_ops *ca; + char *saved_clone, *clone, *name; + int ret = 0; + + saved_clone = clone = kstrdup(val, GFP_USER); + if (!clone) + return -ENOMEM; + + spin_lock(&tcp_cong_list_lock); + /* pass 1 check for bad entries */ + while ((name = strsep(&clone, " ")) && *name) { + ca = tcp_ca_find(name); + if (!ca) { + ret = -ENOENT; + goto out; + } + } + + /* pass 2 clear old values */ + list_for_each_entry_rcu(ca, &tcp_cong_list, list) + ca->flags &= ~TCP_CONG_NON_RESTRICTED; + + /* pass 3 mark as allowed */ + while ((name = strsep(&val, " ")) && *name) { + ca = tcp_ca_find(name); + WARN_ON(!ca); + if (ca) + ca->flags |= TCP_CONG_NON_RESTRICTED; + } +out: + spin_unlock(&tcp_cong_list_lock); + kfree(saved_clone); + + return ret; +} + +/* Change congestion control for socket */ +int tcp_set_congestion_control(struct sock *sk, const char *name) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + const struct tcp_congestion_ops *ca; + int err = 0; + + if (icsk->icsk_ca_dst_locked) + return -EPERM; + + rcu_read_lock(); + ca = __tcp_ca_find_autoload(name); + /* No change asking for existing value */ + if (ca == icsk->icsk_ca_ops) { + icsk->icsk_ca_setsockopt = 1; + goto out; + } + if (!ca) + err = -ENOENT; + else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || + ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))) + err = -EPERM; + else if (!try_module_get(ca->owner)) + err = -EBUSY; + else + tcp_reinit_congestion_control(sk, ca); + out: + rcu_read_unlock(); + return err; +} + +/* Slow start is used when congestion window is no greater than the slow start + * threshold. We base on RFC2581 and also handle stretch ACKs properly. + * We do not implement RFC3465 Appropriate Byte Counting (ABC) per se but + * something better;) a packet is only considered (s)acked in its entirety to + * defend the ACK attacks described in the RFC. Slow start processes a stretch + * ACK of degree N as if N acks of degree 1 are received back to back except + * ABC caps N to 2. Slow start exits when cwnd grows over ssthresh and + * returns the leftover acks to adjust cwnd in congestion avoidance mode. + */ +u32 tcp_slow_start(struct tcp_sock *tp, u32 acked) +{ + u32 cwnd = tp->snd_cwnd + acked; + + if (cwnd > tp->snd_ssthresh) + cwnd = tp->snd_ssthresh + 1; + acked -= cwnd - tp->snd_cwnd; + tp->snd_cwnd = min(cwnd, tp->snd_cwnd_clamp); + + return acked; +} +EXPORT_SYMBOL_GPL(tcp_slow_start); + +/* In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd (or alternative w), + * for every packet that was ACKed. + */ +void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked) +{ + /* If credits accumulated at a higher w, apply them gently now. */ + if (tp->snd_cwnd_cnt >= w) { + tp->snd_cwnd_cnt = 0; + tp->snd_cwnd++; + } + + tp->snd_cwnd_cnt += acked; + if (tp->snd_cwnd_cnt >= w) { + u32 delta = tp->snd_cwnd_cnt / w; + + tp->snd_cwnd_cnt -= delta * w; + tp->snd_cwnd += delta; + } + tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_cwnd_clamp); +} +EXPORT_SYMBOL_GPL(tcp_cong_avoid_ai); + +/* + * TCP Reno congestion control + * This is special case used for fallback as well. + */ +/* This is Jacobson's slow start and congestion avoidance. + * SIGCOMM '88, p. 328. + */ +void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked) +{ + struct tcp_sock *tp = tcp_sk(sk); + + if (!tcp_is_cwnd_limited(sk)) + return; + + /* In "safe" area, increase. */ + if (tp->snd_cwnd <= tp->snd_ssthresh) { + acked = tcp_slow_start(tp, acked); + if (!acked) + return; + } + /* In dangerous area, increase slowly. */ + tcp_cong_avoid_ai(tp, tp->snd_cwnd, acked); +} +EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid); + +/* Slow start threshold is half the congestion window (min 2) */ +u32 tcp_reno_ssthresh(struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + + return max(tp->snd_cwnd >> 1U, 2U); +} +EXPORT_SYMBOL_GPL(tcp_reno_ssthresh); + +struct tcp_congestion_ops tcp_reno = { + .flags = TCP_CONG_NON_RESTRICTED, + .name = "reno", + .owner = THIS_MODULE, + .ssthresh = tcp_reno_ssthresh, + .cong_avoid = tcp_reno_cong_avoid, +}; |