[thirdparty/linux.git] / net / ipv4 / tcp_dctcp.c

/* DataCenter TCP (DCTCP) congestion control.
 *
 * http://simula.stanford.edu/~alizade/Site/DCTCP.html
 *
 * This is an implementation of DCTCP over Reno, an enhancement to the
 * TCP congestion control algorithm designed for data centers. DCTCP
 * leverages Explicit Congestion Notification (ECN) in the network to
 * provide multi-bit feedback to the end hosts. DCTCP's goal is to meet
 * the following three data center transport requirements:
 *
 *  - High burst tolerance (incast due to partition/aggregate)
 *  - Low latency (short flows, queries)
 *  - High throughput (continuous data updates, large file transfers)
 *    with commodity shallow buffered switches
 *
 * The algorithm is described in detail in the following two papers:
 *
 * 1) Mohammad Alizadeh, Albert Greenberg, David A. Maltz, Jitendra Padhye,
 *    Parveen Patel, Balaji Prabhakar, Sudipta Sengupta, and Murari Sridharan:
 *      "Data Center TCP (DCTCP)", Data Center Networks session
 *      Proc. ACM SIGCOMM, New Delhi, 2010.
 *   http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
 *
 * 2) Mohammad Alizadeh, Adel Javanmard, and Balaji Prabhakar:
 *      "Analysis of DCTCP: Stability, Convergence, and Fairness"
 *      Proc. ACM SIGMETRICS, San Jose, 2011.
 *   http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp_analysis-full.pdf
 *
 * Initial prototype from Abdul Kabbani, Masato Yasuda and Mohammad Alizadeh.
 *
 * Authors:
 *
 *	Daniel Borkmann <dborkman@redhat.com>
 *	Florian Westphal <fw@strlen.de>
 *	Glenn Judd <glenn.judd@morganstanley.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 */

#include <linux/module.h>
#include <linux/mm.h>
#include <net/tcp.h>
#include <linux/inet_diag.h>

#define DCTCP_MAX_ALPHA	1024U

struct dctcp {
	u32 acked_bytes_ecn;
	u32 acked_bytes_total;
	u32 prior_snd_una;
	u32 prior_rcv_nxt;
	u32 dctcp_alpha;
	u32 next_seq;
	u32 ce_state;
	u32 delayed_ack_reserved;
};

static unsigned int dctcp_shift_g __read_mostly = 4; /* g = 1/2^4 */
module_param(dctcp_shift_g, uint, 0644);
MODULE_PARM_DESC(dctcp_shift_g, "parameter g for updating dctcp_alpha");

static unsigned int dctcp_alpha_on_init __read_mostly = DCTCP_MAX_ALPHA;
module_param(dctcp_alpha_on_init, uint, 0644);
MODULE_PARM_DESC(dctcp_alpha_on_init, "parameter for initial alpha value");

static unsigned int dctcp_clamp_alpha_on_loss __read_mostly;
module_param(dctcp_clamp_alpha_on_loss, uint, 0644);
MODULE_PARM_DESC(dctcp_clamp_alpha_on_loss,
		 "parameter for clamping alpha on loss");

static struct tcp_congestion_ops dctcp_reno;

static void dctcp_reset(const struct tcp_sock *tp, struct dctcp *ca)
{
	ca->next_seq = tp->snd_nxt;

	ca->acked_bytes_ecn = 0;
	ca->acked_bytes_total = 0;
}

static void dctcp_init(struct sock *sk)
{
	const struct tcp_sock *tp = tcp_sk(sk);

	if ((tp->ecn_flags & TCP_ECN_OK) ||
	    (sk->sk_state == TCP_LISTEN ||
	     sk->sk_state == TCP_CLOSE)) {
		struct dctcp *ca = inet_csk_ca(sk);

		ca->prior_snd_una = tp->snd_una;
		ca->prior_rcv_nxt = tp->rcv_nxt;

		ca->dctcp_alpha = min(dctcp_alpha_on_init, DCTCP_MAX_ALPHA);

		ca->delayed_ack_reserved = 0;
		ca->ce_state = 0;

		dctcp_reset(tp, ca);
		return;
	}

	/* No ECN support? Fall back to Reno. Also need to clear
	 * ECT from sk since it is set during 3WHS for DCTCP.
	 */
	inet_csk(sk)->icsk_ca_ops = &dctcp_reno;
	INET_ECN_dontxmit(sk);
}

static u32 dctcp_ssthresh(struct sock *sk)
{
	const struct dctcp *ca = inet_csk_ca(sk);
	struct tcp_sock *tp = tcp_sk(sk);

	return max(tp->snd_cwnd - ((tp->snd_cwnd * ca->dctcp_alpha) >> 11U), 2U);
}

/* Minimal DCTP CE state machine:
 *
 * S:	0 <- last pkt was non-CE
 *	1 <- last pkt was CE
 */

static void dctcp_ce_state_0_to_1(struct sock *sk)
{
	struct dctcp *ca = inet_csk_ca(sk);
	struct tcp_sock *tp = tcp_sk(sk);

	/* State has changed from CE=0 to CE=1 and delayed
	 * ACK has not sent yet.
	 */
	if (!ca->ce_state && ca->delayed_ack_reserved) {
		u32 tmp_rcv_nxt;

		/* Save current rcv_nxt. */
		tmp_rcv_nxt = tp->rcv_nxt;

		/* Generate previous ack with CE=0. */
		tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
		tp->rcv_nxt = ca->prior_rcv_nxt;

		tcp_send_ack(sk);

		/* Recover current rcv_nxt. */
		tp->rcv_nxt = tmp_rcv_nxt;
	}

	ca->prior_rcv_nxt = tp->rcv_nxt;
	ca->ce_state = 1;

	tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
}

static void dctcp_ce_state_1_to_0(struct sock *sk)
{
	struct dctcp *ca = inet_csk_ca(sk);
	struct tcp_sock *tp = tcp_sk(sk);

	/* State has changed from CE=1 to CE=0 and delayed
	 * ACK has not sent yet.
	 */
	if (ca->ce_state && ca->delayed_ack_reserved) {
		u32 tmp_rcv_nxt;

		/* Save current rcv_nxt. */
		tmp_rcv_nxt = tp->rcv_nxt;

		/* Generate previous ack with CE=1. */
		tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
		tp->rcv_nxt = ca->prior_rcv_nxt;

		tcp_send_ack(sk);

		/* Recover current rcv_nxt. */
		tp->rcv_nxt = tmp_rcv_nxt;
	}

	ca->prior_rcv_nxt = tp->rcv_nxt;
	ca->ce_state = 0;

	tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
}

static void dctcp_update_alpha(struct sock *sk, u32 flags)
{
	const struct tcp_sock *tp = tcp_sk(sk);
	struct dctcp *ca = inet_csk_ca(sk);
	u32 acked_bytes = tp->snd_una - ca->prior_snd_una;

	/* If ack did not advance snd_una, count dupack as MSS size.
	 * If ack did update window, do not count it at all.
	 */
	if (acked_bytes == 0 && !(flags & CA_ACK_WIN_UPDATE))
		acked_bytes = inet_csk(sk)->icsk_ack.rcv_mss;
	if (acked_bytes) {
		ca->acked_bytes_total += acked_bytes;
		ca->prior_snd_una = tp->snd_una;

		if (flags & CA_ACK_ECE)
			ca->acked_bytes_ecn += acked_bytes;
	}

	/* Expired RTT */
	if (!before(tp->snd_una, ca->next_seq)) {
		u64 bytes_ecn = ca->acked_bytes_ecn;
		u32 alpha = ca->dctcp_alpha;

		/* alpha = (1 - g) * alpha + g * F */

		alpha -= min_not_zero(alpha, alpha >> dctcp_shift_g);
		if (bytes_ecn) {
			/* If dctcp_shift_g == 1, a 32bit value would overflow
			 * after 8 Mbytes.
			 */
			bytes_ecn <<= (10 - dctcp_shift_g);
			do_div(bytes_ecn, max(1U, ca->acked_bytes_total));

			alpha = min(alpha + (u32)bytes_ecn, DCTCP_MAX_ALPHA);
		}
		/* dctcp_alpha can be read from dctcp_get_info() without
		 * synchro, so we ask compiler to not use dctcp_alpha
		 * as a temporary variable in prior operations.
		 */
		WRITE_ONCE(ca->dctcp_alpha, alpha);
		dctcp_reset(tp, ca);
	}
}

static void dctcp_state(struct sock *sk, u8 new_state)
{
	if (dctcp_clamp_alpha_on_loss && new_state == TCP_CA_Loss) {
		struct dctcp *ca = inet_csk_ca(sk);

		/* If this extension is enabled, we clamp dctcp_alpha to
		 * max on packet loss; the motivation is that dctcp_alpha
		 * is an indicator to the extend of congestion and packet
		 * loss is an indicator of extreme congestion; setting
		 * this in practice turned out to be beneficial, and
		 * effectively assumes total congestion which reduces the
		 * window by half.
		 */
		ca->dctcp_alpha = DCTCP_MAX_ALPHA;
	}
}

static void dctcp_update_ack_reserved(struct sock *sk, enum tcp_ca_event ev)
{
	struct dctcp *ca = inet_csk_ca(sk);

	switch (ev) {
	case CA_EVENT_DELAYED_ACK:
		if (!ca->delayed_ack_reserved)
			ca->delayed_ack_reserved = 1;
		break;
	case CA_EVENT_NON_DELAYED_ACK:
		if (ca->delayed_ack_reserved)
			ca->delayed_ack_reserved = 0;
		break;
	default:
		/* Don't care for the rest. */
		break;
	}
}

static void dctcp_cwnd_event(struct sock *sk, enum tcp_ca_event ev)
{
	switch (ev) {
	case CA_EVENT_ECN_IS_CE:
		dctcp_ce_state_0_to_1(sk);
		break;
	case CA_EVENT_ECN_NO_CE:
		dctcp_ce_state_1_to_0(sk);
		break;
	case CA_EVENT_DELAYED_ACK:
	case CA_EVENT_NON_DELAYED_ACK:
		dctcp_update_ack_reserved(sk, ev);
		break;
	default:
		/* Don't care for the rest. */
		break;
	}
}

static size_t dctcp_get_info(struct sock *sk, u32 ext, int *attr,
			     union tcp_cc_info *info)
{
	const struct dctcp *ca = inet_csk_ca(sk);

	/* Fill it also in case of VEGASINFO due to req struct limits.
	 * We can still correctly retrieve it later.
	 */
	if (ext & (1 << (INET_DIAG_DCTCPINFO - 1)) ||
	    ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
		memset(&info->dctcp, 0, sizeof(info->dctcp));
		if (inet_csk(sk)->icsk_ca_ops != &dctcp_reno) {
			info->dctcp.dctcp_enabled = 1;
			info->dctcp.dctcp_ce_state = (u16) ca->ce_state;
			info->dctcp.dctcp_alpha = ca->dctcp_alpha;
			info->dctcp.dctcp_ab_ecn = ca->acked_bytes_ecn;
			info->dctcp.dctcp_ab_tot = ca->acked_bytes_total;
		}

		*attr = INET_DIAG_DCTCPINFO;
		return sizeof(info->dctcp);
	}
	return 0;
}

static struct tcp_congestion_ops dctcp __read_mostly = {
	.init		= dctcp_init,
	.in_ack_event   = dctcp_update_alpha,
	.cwnd_event	= dctcp_cwnd_event,
	.ssthresh	= dctcp_ssthresh,
	.cong_avoid	= tcp_reno_cong_avoid,
	.set_state	= dctcp_state,
	.get_info	= dctcp_get_info,
	.flags		= TCP_CONG_NEEDS_ECN,
	.owner		= THIS_MODULE,
	.name		= "dctcp",
};

static struct tcp_congestion_ops dctcp_reno __read_mostly = {
	.ssthresh	= tcp_reno_ssthresh,
	.cong_avoid	= tcp_reno_cong_avoid,
	.get_info	= dctcp_get_info,
	.owner		= THIS_MODULE,
	.name		= "dctcp-reno",
};

static int __init dctcp_register(void)
{
	BUILD_BUG_ON(sizeof(struct dctcp) > ICSK_CA_PRIV_SIZE);
	return tcp_register_congestion_control(&dctcp);
}

static void __exit dctcp_unregister(void)
{
	tcp_unregister_congestion_control(&dctcp);
}

module_init(dctcp_register);
module_exit(dctcp_unregister);

MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
MODULE_AUTHOR("Glenn Judd <glenn.judd@morganstanley.com>");

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("DataCenter TCP (DCTCP)");
Commit	Line	Data
e3118e83 DB	1	/* DataCenter TCP (DCTCP) congestion control.
	2	*
	3	* http://simula.stanford.edu/~alizade/Site/DCTCP.html
	4	*
	5	* This is an implementation of DCTCP over Reno, an enhancement to the
	6	* TCP congestion control algorithm designed for data centers. DCTCP
	7	* leverages Explicit Congestion Notification (ECN) in the network to
	8	* provide multi-bit feedback to the end hosts. DCTCP's goal is to meet
	9	* the following three data center transport requirements:
	10	*
	11	* - High burst tolerance (incast due to partition/aggregate)
	12	* - Low latency (short flows, queries)
	13	* - High throughput (continuous data updates, large file transfers)
	14	* with commodity shallow buffered switches
	15	*
	16	* The algorithm is described in detail in the following two papers:
	17	*
	18	* 1) Mohammad Alizadeh, Albert Greenberg, David A. Maltz, Jitendra Padhye,
	19	* Parveen Patel, Balaji Prabhakar, Sudipta Sengupta, and Murari Sridharan:
	20	* "Data Center TCP (DCTCP)", Data Center Networks session
	21	* Proc. ACM SIGCOMM, New Delhi, 2010.
	22	* http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
	23	*
	24	* 2) Mohammad Alizadeh, Adel Javanmard, and Balaji Prabhakar:
	25	* "Analysis of DCTCP: Stability, Convergence, and Fairness"
	26	* Proc. ACM SIGMETRICS, San Jose, 2011.
	27	* http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp_analysis-full.pdf
	28	*
	29	* Initial prototype from Abdul Kabbani, Masato Yasuda and Mohammad Alizadeh.
	30	*
	31	* Authors:
	32	*
	33	* Daniel Borkmann <dborkman@redhat.com>
	34	* Florian Westphal <fw@strlen.de>
	35	* Glenn Judd <glenn.judd@morganstanley.com>
	36	*
	37	* This program is free software; you can redistribute it and/or modify
	38	* it under the terms of the GNU General Public License as published by
	39	* the Free Software Foundation; either version 2 of the License, or (at
	40	* your option) any later version.
	41	*/
	42
	43	#include <linux/module.h>
	44	#include <linux/mm.h>
	45	#include <net/tcp.h>
	46	#include <linux/inet_diag.h>
	47
	48	#define DCTCP_MAX_ALPHA 1024U
	49
	50	struct dctcp {
	51	u32 acked_bytes_ecn;
	52	u32 acked_bytes_total;
	53	u32 prior_snd_una;
	54	u32 prior_rcv_nxt;
	55	u32 dctcp_alpha;
	56	u32 next_seq;
	57	u32 ce_state;
	58	u32 delayed_ack_reserved;
	59	};
	60
	61	static unsigned int dctcp_shift_g __read_mostly = 4; /* g = 1/2^4 */
	62	module_param(dctcp_shift_g, uint, 0644);
	63	MODULE_PARM_DESC(dctcp_shift_g, "parameter g for updating dctcp_alpha");
	64
65	static unsigned int dctcp_alpha_on_init __read_mostly = DCTCP_MAX_ALPHA;
66	module_param(dctcp_alpha_on_init, uint, 0644);
67	MODULE_PARM_DESC(dctcp_alpha_on_init, "parameter for initial alpha value");
68
69	static unsigned int dctcp_clamp_alpha_on_loss __read_mostly;
70	module_param(dctcp_clamp_alpha_on_loss, uint, 0644);
71	MODULE_PARM_DESC(dctcp_clamp_alpha_on_loss,
72	"parameter for clamping alpha on loss");
73
74	static struct tcp_congestion_ops dctcp_reno;
75
76	static void dctcp_reset(const struct tcp_sock tp, struct dctcp ca)
77	{
78	ca->next_seq = tp->snd_nxt;
79
80	ca->acked_bytes_ecn = 0;
81	ca->acked_bytes_total = 0;
82	}
83
84	static void dctcp_init(struct sock *sk)
85	{
86	const struct tcp_sock *tp = tcp_sk(sk);
87
88	if ((tp->ecn_flags & TCP_ECN_OK) \|\|
89	(sk->sk_state == TCP_LISTEN \|\|
90	sk->sk_state == TCP_CLOSE)) {
91	struct dctcp *ca = inet_csk_ca(sk);
92
93	ca->prior_snd_una = tp->snd_una;
94	ca->prior_rcv_nxt = tp->rcv_nxt;
95
96	ca->dctcp_alpha = min(dctcp_alpha_on_init, DCTCP_MAX_ALPHA);
97
98	ca->delayed_ack_reserved = 0;
99	ca->ce_state = 0;
100
101	dctcp_reset(tp, ca);
102	return;
103	}
104
105	/* No ECN support? Fall back to Reno. Also need to clear
106	* ECT from sk since it is set during 3WHS for DCTCP.
107	*/
108	inet_csk(sk)->icsk_ca_ops = &dctcp_reno;
109	INET_ECN_dontxmit(sk);
110	}
111
112	static u32 dctcp_ssthresh(struct sock *sk)
113	{
114	const struct dctcp *ca = inet_csk_ca(sk);
115	struct tcp_sock *tp = tcp_sk(sk);
116
117	return max(tp->snd_cwnd - ((tp->snd_cwnd * ca->dctcp_alpha) >> 11U), 2U);
118	}
119
120	/* Minimal DCTP CE state machine:
121	*
122	* S: 0 <- last pkt was non-CE
123	* 1 <- last pkt was CE
124	*/
125
126	static void dctcp_ce_state_0_to_1(struct sock *sk)
127	{
128	struct dctcp *ca = inet_csk_ca(sk);
129	struct tcp_sock *tp = tcp_sk(sk);
130
131	/* State has changed from CE=0 to CE=1 and delayed
132	* ACK has not sent yet.
133	*/
134	if (!ca->ce_state && ca->delayed_ack_reserved) {
135	u32 tmp_rcv_nxt;
136
137	/* Save current rcv_nxt. */
138	tmp_rcv_nxt = tp->rcv_nxt;
139
140	/* Generate previous ack with CE=0. */
141	tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
142	tp->rcv_nxt = ca->prior_rcv_nxt;
143
144	tcp_send_ack(sk);
145
146	/* Recover current rcv_nxt. */
147	tp->rcv_nxt = tmp_rcv_nxt;
148	}
149
150	ca->prior_rcv_nxt = tp->rcv_nxt;
151	ca->ce_state = 1;
152
153	tp->ecn_flags \|= TCP_ECN_DEMAND_CWR;
154	}
155
156	static void dctcp_ce_state_1_to_0(struct sock *sk)
157	{
158	struct dctcp *ca = inet_csk_ca(sk);
159	struct tcp_sock *tp = tcp_sk(sk);
160
161	/* State has changed from CE=1 to CE=0 and delayed
162	* ACK has not sent yet.
163	*/
164	if (ca->ce_state && ca->delayed_ack_reserved) {
165	u32 tmp_rcv_nxt;
166
167	/* Save current rcv_nxt. */
168	tmp_rcv_nxt = tp->rcv_nxt;
169
170	/* Generate previous ack with CE=1. */
171	tp->ecn_flags \|= TCP_ECN_DEMAND_CWR;
172	tp->rcv_nxt = ca->prior_rcv_nxt;
173
174	tcp_send_ack(sk);
175
176	/* Recover current rcv_nxt. */
177	tp->rcv_nxt = tmp_rcv_nxt;
178	}
179
180	ca->prior_rcv_nxt = tp->rcv_nxt;
181	ca->ce_state = 0;
182
183	tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
184	}
185
186	static void dctcp_update_alpha(struct sock *sk, u32 flags)
187	{
188	const struct tcp_sock *tp = tcp_sk(sk);
189	struct dctcp *ca = inet_csk_ca(sk);
190	u32 acked_bytes = tp->snd_una - ca->prior_snd_una;
191
192	/* If ack did not advance snd_una, count dupack as MSS size.
193	* If ack did update window, do not count it at all.
194	*/
195	if (acked_bytes == 0 && !(flags & CA_ACK_WIN_UPDATE))
196	acked_bytes = inet_csk(sk)->icsk_ack.rcv_mss;
197	if (acked_bytes) {
198	ca->acked_bytes_total += acked_bytes;
199	ca->prior_snd_una = tp->snd_una;
200
201	if (flags & CA_ACK_ECE)
202	ca->acked_bytes_ecn += acked_bytes;
203	}
204
205	/* Expired RTT */
206	if (!before(tp->snd_una, ca->next_seq)) {
f9c2ff22 ED	207	u64 bytes_ecn = ca->acked_bytes_ecn;
f9c2ff22 ED	208	u32 alpha = ca->dctcp_alpha;
e3118e83 DB	209
e3118e83 DB	210	/* alpha = (1 - g) * alpha + g * F */
e3118e83	211
c80dbe04	212	alpha -= min_not_zero(alpha, alpha >> dctcp_shift_g);
f9c2ff22 ED	213	if (bytes_ecn) {
	214	/* If dctcp_shift_g == 1, a 32bit value would overflow
	215	* after 8 Mbytes.
	216	*/
	217	bytes_ecn <<= (10 - dctcp_shift_g);
	218	do_div(bytes_ecn, max(1U, ca->acked_bytes_total));
	219
	220	alpha = min(alpha + (u32)bytes_ecn, DCTCP_MAX_ALPHA);
	221	}
	222	/* dctcp_alpha can be read from dctcp_get_info() without
	223	* synchro, so we ask compiler to not use dctcp_alpha
	224	* as a temporary variable in prior operations.
	225	*/
	226	WRITE_ONCE(ca->dctcp_alpha, alpha);
e3118e83 DB	227	dctcp_reset(tp, ca);
	228	}
	229	}
	230
	231	static void dctcp_state(struct sock *sk, u8 new_state)
	232	{
	233	if (dctcp_clamp_alpha_on_loss && new_state == TCP_CA_Loss) {
	234	struct dctcp *ca = inet_csk_ca(sk);
	235
	236	/* If this extension is enabled, we clamp dctcp_alpha to
	237	* max on packet loss; the motivation is that dctcp_alpha
	238	* is an indicator to the extend of congestion and packet
	239	* loss is an indicator of extreme congestion; setting
	240	* this in practice turned out to be beneficial, and
	241	* effectively assumes total congestion which reduces the
	242	* window by half.
	243	*/
	244	ca->dctcp_alpha = DCTCP_MAX_ALPHA;
	245	}
	246	}
	247
	248	static void dctcp_update_ack_reserved(struct sock *sk, enum tcp_ca_event ev)
	249	{
	250	struct dctcp *ca = inet_csk_ca(sk);
	251
	252	switch (ev) {
	253	case CA_EVENT_DELAYED_ACK:
	254	if (!ca->delayed_ack_reserved)
	255	ca->delayed_ack_reserved = 1;
	256	break;
	257	case CA_EVENT_NON_DELAYED_ACK:
	258	if (ca->delayed_ack_reserved)
	259	ca->delayed_ack_reserved = 0;
	260	break;
	261	default:
	262	/* Don't care for the rest. */
	263	break;
	264	}
	265	}
	266
	267	static void dctcp_cwnd_event(struct sock *sk, enum tcp_ca_event ev)
	268	{
	269	switch (ev) {
	270	case CA_EVENT_ECN_IS_CE:
	271	dctcp_ce_state_0_to_1(sk);
	272	break;
	273	case CA_EVENT_ECN_NO_CE:
	274	dctcp_ce_state_1_to_0(sk);
	275	break;
	276	case CA_EVENT_DELAYED_ACK:
	277	case CA_EVENT_NON_DELAYED_ACK:
	278	dctcp_update_ack_reserved(sk, ev);
	279	break;
	280	default:
	281	/* Don't care for the rest. */
	282	break;
	283	}
	284	}
	285
64f40ff5 ED	286	static size_t dctcp_get_info(struct sock sk, u32 ext, int attr,
64f40ff5 ED	287	union tcp_cc_info *info)
e3118e83 DB	288	{
	289	const struct dctcp *ca = inet_csk_ca(sk);
	290
	291	/* Fill it also in case of VEGASINFO due to req struct limits.
	292	* We can still correctly retrieve it later.
	293	*/
	294	if (ext & (1 << (INET_DIAG_DCTCPINFO - 1)) \|\|
	295	ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
dcf1158b	296	memset(&info->dctcp, 0, sizeof(info->dctcp));
e3118e83	297	if (inet_csk(sk)->icsk_ca_ops != &dctcp_reno) {
64f40ff5 ED	298	info->dctcp.dctcp_enabled = 1;
	299	info->dctcp.dctcp_ce_state = (u16) ca->ce_state;
	300	info->dctcp.dctcp_alpha = ca->dctcp_alpha;
	301	info->dctcp.dctcp_ab_ecn = ca->acked_bytes_ecn;
	302	info->dctcp.dctcp_ab_tot = ca->acked_bytes_total;
e3118e83 DB	303	}
e3118e83 DB	304
64f40ff5	305	*attr = INET_DIAG_DCTCPINFO;
dcf1158b	306	return sizeof(info->dctcp);
e3118e83	307	}
521f1cf1	308	return 0;
e3118e83 DB	309	}
	310
	311	static struct tcp_congestion_ops dctcp __read_mostly = {
	312	.init = dctcp_init,
	313	.in_ack_event = dctcp_update_alpha,
	314	.cwnd_event = dctcp_cwnd_event,
	315	.ssthresh = dctcp_ssthresh,
	316	.cong_avoid = tcp_reno_cong_avoid,
	317	.set_state = dctcp_state,
	318	.get_info = dctcp_get_info,
	319	.flags = TCP_CONG_NEEDS_ECN,
	320	.owner = THIS_MODULE,
	321	.name = "dctcp",
	322	};
	323
	324	static struct tcp_congestion_ops dctcp_reno __read_mostly = {
	325	.ssthresh = tcp_reno_ssthresh,
	326	.cong_avoid = tcp_reno_cong_avoid,
	327	.get_info = dctcp_get_info,
	328	.owner = THIS_MODULE,
	329	.name = "dctcp-reno",
	330	};
	331
	332	static int __init dctcp_register(void)
	333	{
	334	BUILD_BUG_ON(sizeof(struct dctcp) > ICSK_CA_PRIV_SIZE);
	335	return tcp_register_congestion_control(&dctcp);
	336	}
	337
	338	static void __exit dctcp_unregister(void)
	339	{
	340	tcp_unregister_congestion_control(&dctcp);
	341	}
	342
	343	module_init(dctcp_register);
	344	module_exit(dctcp_unregister);
	345
	346	MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
	347	MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
	348	MODULE_AUTHOR("Glenn Judd <glenn.judd@morganstanley.com>");
	349
	350	MODULE_LICENSE("GPL v2");
	351	MODULE_DESCRIPTION("DataCenter TCP (DCTCP)");