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

// SPDX-License-Identifier: GPL-2.0-or-later
/* 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>
 */

#include <linux/btf.h>
#include <linux/btf_ids.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <net/tcp.h>
#include <linux/inet_diag.h>
#include "tcp_dctcp.h"

#define DCTCP_MAX_ALPHA	1024U

struct dctcp {
	u32 old_delivered;
	u32 old_delivered_ce;
	u32 prior_rcv_nxt;
	u32 dctcp_alpha;
	u32 next_seq;
	u32 ce_state;
	u32 loss_cwnd;
	struct tcp_plb_state plb;
};

static unsigned int dctcp_shift_g __read_mostly = 4; /* g = 1/2^4 */

static int dctcp_shift_g_set(const char *val, const struct kernel_param *kp)
{
	return param_set_uint_minmax(val, kp, 0, 10);
}

static const struct kernel_param_ops dctcp_shift_g_ops = {
	.set = dctcp_shift_g_set,
	.get = param_get_uint,
};

module_param_cb(dctcp_shift_g, &dctcp_shift_g_ops, &dctcp_shift_g, 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 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->old_delivered = tp->delivered;
	ca->old_delivered_ce = tp->delivered_ce;
}

__bpf_kfunc 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_rcv_nxt = tp->rcv_nxt;

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

		ca->loss_cwnd = 0;
		ca->ce_state = 0;

		dctcp_reset(tp, ca);
		tcp_plb_init(sk, &ca->plb);

		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);
}

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

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

__bpf_kfunc 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);

	/* Expired RTT */
	if (!before(tp->snd_una, ca->next_seq)) {
		u32 delivered = tp->delivered - ca->old_delivered;
		u32 delivered_ce = tp->delivered_ce - ca->old_delivered_ce;
		u32 alpha = ca->dctcp_alpha;
		u32 ce_ratio = 0;

		if (delivered > 0) {
			/* dctcp_alpha keeps EWMA of fraction of ECN marked
			 * packets. Because of EWMA smoothing, PLB reaction can
			 * be slow so we use ce_ratio which is an instantaneous
			 * measure of congestion. ce_ratio is the fraction of
			 * ECN marked packets in the previous RTT.
			 */
			if (delivered_ce > 0)
				ce_ratio = (delivered_ce << TCP_PLB_SCALE) / delivered;
			tcp_plb_update_state(sk, &ca->plb, (int)ce_ratio);
			tcp_plb_check_rehash(sk, &ca->plb);
		}

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

		alpha -= min_not_zero(alpha, alpha >> dctcp_shift_g);
		if (delivered_ce) {

			/* If dctcp_shift_g == 1, a 32bit value would overflow
			 * after 8 M packets.
			 */
			delivered_ce <<= (10 - dctcp_shift_g);
			delivered_ce /= max(1U, delivered);

			alpha = min(alpha + delivered_ce, 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_react_to_loss(struct sock *sk)
{
	struct dctcp *ca = inet_csk_ca(sk);
	struct tcp_sock *tp = tcp_sk(sk);

	ca->loss_cwnd = tcp_snd_cwnd(tp);
	tp->snd_ssthresh = max(tcp_snd_cwnd(tp) >> 1U, 2U);
}

__bpf_kfunc static void dctcp_state(struct sock *sk, u8 new_state)
{
	if (new_state == TCP_CA_Recovery &&
	    new_state != inet_csk(sk)->icsk_ca_state)
		dctcp_react_to_loss(sk);
	/* We handle RTO in dctcp_cwnd_event to ensure that we perform only
	 * one loss-adjustment per RTT.
	 */
}

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

	switch (ev) {
	case CA_EVENT_ECN_IS_CE:
	case CA_EVENT_ECN_NO_CE:
		dctcp_ece_ack_update(sk, ev, &ca->prior_rcv_nxt, &ca->ce_state);
		break;
	case CA_EVENT_LOSS:
		tcp_plb_update_state_upon_rto(sk, &ca->plb);
		dctcp_react_to_loss(sk);
		break;
	case CA_EVENT_TX_START:
		tcp_plb_check_rehash(sk, &ca->plb); /* Maybe rehash when inflight is 0 */
		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);
	const struct tcp_sock *tp = tcp_sk(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 = tp->mss_cache *
						   (tp->delivered_ce - ca->old_delivered_ce);
			info->dctcp.dctcp_ab_tot = tp->mss_cache *
						   (tp->delivered - ca->old_delivered);
		}

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

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

	return max(tcp_snd_cwnd(tp), ca->loss_cwnd);
}

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,
	.undo_cwnd	= dctcp_cwnd_undo,
	.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,
	.undo_cwnd	= tcp_reno_undo_cwnd,
	.get_info	= dctcp_get_info,
	.owner		= THIS_MODULE,
	.name		= "dctcp-reno",
};

BTF_KFUNCS_START(tcp_dctcp_check_kfunc_ids)
BTF_ID_FLAGS(func, dctcp_init)
BTF_ID_FLAGS(func, dctcp_update_alpha)
BTF_ID_FLAGS(func, dctcp_cwnd_event)
BTF_ID_FLAGS(func, dctcp_ssthresh)
BTF_ID_FLAGS(func, dctcp_cwnd_undo)
BTF_ID_FLAGS(func, dctcp_state)
BTF_KFUNCS_END(tcp_dctcp_check_kfunc_ids)

static const struct btf_kfunc_id_set tcp_dctcp_kfunc_set = {
	.owner = THIS_MODULE,
	.set   = &tcp_dctcp_check_kfunc_ids,
};

static int __init dctcp_register(void)
{
	int ret;

	BUILD_BUG_ON(sizeof(struct dctcp) > ICSK_CA_PRIV_SIZE);

	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &tcp_dctcp_kfunc_set);
	if (ret < 0)
		return ret;
	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
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
e3118e83 DB	2	/* DataCenter TCP (DCTCP) congestion control.
	3	*
	4	* http://simula.stanford.edu/~alizade/Site/DCTCP.html
	5	*
	6	* This is an implementation of DCTCP over Reno, an enhancement to the
	7	* TCP congestion control algorithm designed for data centers. DCTCP
	8	* leverages Explicit Congestion Notification (ECN) in the network to
	9	* provide multi-bit feedback to the end hosts. DCTCP's goal is to meet
	10	* the following three data center transport requirements:
	11	*
	12	* - High burst tolerance (incast due to partition/aggregate)
	13	* - Low latency (short flows, queries)
	14	* - High throughput (continuous data updates, large file transfers)
	15	* with commodity shallow buffered switches
	16	*
	17	* The algorithm is described in detail in the following two papers:
	18	*
	19	* 1) Mohammad Alizadeh, Albert Greenberg, David A. Maltz, Jitendra Padhye,
	20	* Parveen Patel, Balaji Prabhakar, Sudipta Sengupta, and Murari Sridharan:
	21	* "Data Center TCP (DCTCP)", Data Center Networks session
	22	* Proc. ACM SIGCOMM, New Delhi, 2010.
	23	* http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
	24	*
	25	* 2) Mohammad Alizadeh, Adel Javanmard, and Balaji Prabhakar:
	26	* "Analysis of DCTCP: Stability, Convergence, and Fairness"
	27	* Proc. ACM SIGMETRICS, San Jose, 2011.
	28	* http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp_analysis-full.pdf
	29	*
	30	* Initial prototype from Abdul Kabbani, Masato Yasuda and Mohammad Alizadeh.
	31	*
	32	* Authors:
	33	*
	34	* Daniel Borkmann <dborkman@redhat.com>
	35	* Florian Westphal <fw@strlen.de>
	36	* Glenn Judd <glenn.judd@morganstanley.com>
e3118e83 DB	37	*/
e3118e83 DB	38
0e32dfc8 KKD	39	#include <linux/btf.h>
0e32dfc8 KKD	40	#include <linux/btf_ids.h>
e3118e83 DB	41	#include <linux/module.h>
	42	#include <linux/mm.h>
	43	#include <net/tcp.h>
	44	#include <linux/inet_diag.h>
ffd177de	45	#include "tcp_dctcp.h"
e3118e83 DB	46
	47	#define DCTCP_MAX_ALPHA 1024U
	48
	49	struct dctcp {
e3058450 ED	50	u32 old_delivered;
e3058450 ED	51	u32 old_delivered_ce;
e3118e83 DB	52	u32 prior_rcv_nxt;
	53	u32 dctcp_alpha;
	54	u32 next_seq;
	55	u32 ce_state;
ce6dd233	56	u32 loss_cwnd;
c30f8e0b	57	struct tcp_plb_state plb;
e3118e83 DB	58	};
	59
	60	static unsigned int dctcp_shift_g __read_mostly = 4; /* g = 1/2^4 */
3ebc46ca KI	61
	62	static int dctcp_shift_g_set(const char val, const struct kernel_param kp)
	63	{
	64	return param_set_uint_minmax(val, kp, 0, 10);
	65	}
	66
	67	static const struct kernel_param_ops dctcp_shift_g_ops = {
	68	.set = dctcp_shift_g_set,
	69	.get = param_get_uint,
	70	};
	71
	72	module_param_cb(dctcp_shift_g, &dctcp_shift_g_ops, &dctcp_shift_g, 0644);
e3118e83 DB	73	MODULE_PARM_DESC(dctcp_shift_g, "parameter g for updating dctcp_alpha");
	74
	75	static unsigned int dctcp_alpha_on_init __read_mostly = DCTCP_MAX_ALPHA;
	76	module_param(dctcp_alpha_on_init, uint, 0644);
	77	MODULE_PARM_DESC(dctcp_alpha_on_init, "parameter for initial alpha value");
	78
e3118e83 DB	79	static struct tcp_congestion_ops dctcp_reno;
	80
	81	static void dctcp_reset(const struct tcp_sock tp, struct dctcp ca)
	82	{
	83	ca->next_seq = tp->snd_nxt;
	84
e3058450 ED	85	ca->old_delivered = tp->delivered;
e3058450 ED	86	ca->old_delivered_ce = tp->delivered_ce;
e3118e83 DB	87	}
e3118e83 DB	88
400031e0	89	__bpf_kfunc static void dctcp_init(struct sock *sk)
e3118e83 DB	90	{
	91	const struct tcp_sock *tp = tcp_sk(sk);
	92
	93	if ((tp->ecn_flags & TCP_ECN_OK) \|\|
	94	(sk->sk_state == TCP_LISTEN \|\|
	95	sk->sk_state == TCP_CLOSE)) {
	96	struct dctcp *ca = inet_csk_ca(sk);
	97
e3118e83 DB	98	ca->prior_rcv_nxt = tp->rcv_nxt;
	99
	100	ca->dctcp_alpha = min(dctcp_alpha_on_init, DCTCP_MAX_ALPHA);
	101
ce6dd233	102	ca->loss_cwnd = 0;
e3118e83 DB	103	ca->ce_state = 0;
	104
	105	dctcp_reset(tp, ca);
c30f8e0b MAQ	106	tcp_plb_init(sk, &ca->plb);
c30f8e0b MAQ	107
e3118e83 DB	108	return;
	109	}
	110
	111	/* No ECN support? Fall back to Reno. Also need to clear
	112	* ECT from sk since it is set during 3WHS for DCTCP.
	113	*/
	114	inet_csk(sk)->icsk_ca_ops = &dctcp_reno;
	115	INET_ECN_dontxmit(sk);
	116	}
	117
400031e0	118	__bpf_kfunc static u32 dctcp_ssthresh(struct sock *sk)
e3118e83	119	{
ce6dd233	120	struct dctcp *ca = inet_csk_ca(sk);
e3118e83 DB	121	struct tcp_sock *tp = tcp_sk(sk);
e3118e83 DB	122
40570375 ED	123	ca->loss_cwnd = tcp_snd_cwnd(tp);
40570375 ED	124	return max(tcp_snd_cwnd(tp) - ((tcp_snd_cwnd(tp) * ca->dctcp_alpha) >> 11U), 2U);
e3118e83 DB	125	}
e3118e83 DB	126
400031e0	127	__bpf_kfunc static void dctcp_update_alpha(struct sock *sk, u32 flags)
e3118e83	128	{
343dfaa1	129	const struct tcp_sock *tp = tcp_sk(sk);
e3118e83	130	struct dctcp *ca = inet_csk_ca(sk);
e3118e83 DB	131
	132	/* Expired RTT */
	133	if (!before(tp->snd_una, ca->next_seq)) {
c30f8e0b	134	u32 delivered = tp->delivered - ca->old_delivered;
e3058450	135	u32 delivered_ce = tp->delivered_ce - ca->old_delivered_ce;
f9c2ff22	136	u32 alpha = ca->dctcp_alpha;
c30f8e0b MAQ	137	u32 ce_ratio = 0;
	138
	139	if (delivered > 0) {
	140	/* dctcp_alpha keeps EWMA of fraction of ECN marked
	141	* packets. Because of EWMA smoothing, PLB reaction can
	142	* be slow so we use ce_ratio which is an instantaneous
	143	* measure of congestion. ce_ratio is the fraction of
	144	* ECN marked packets in the previous RTT.
	145	*/
	146	if (delivered_ce > 0)
	147	ce_ratio = (delivered_ce << TCP_PLB_SCALE) / delivered;
	148	tcp_plb_update_state(sk, &ca->plb, (int)ce_ratio);
	149	tcp_plb_check_rehash(sk, &ca->plb);
	150	}
e3118e83 DB	151
e3118e83 DB	152	/* alpha = (1 - g) * alpha + g * F */
e3118e83	153
c80dbe04	154	alpha -= min_not_zero(alpha, alpha >> dctcp_shift_g);
e3058450	155	if (delivered_ce) {
e3058450	156
f9c2ff22	157	/* If dctcp_shift_g == 1, a 32bit value would overflow
e3058450	158	* after 8 M packets.
f9c2ff22	159	*/
e3058450 ED	160	delivered_ce <<= (10 - dctcp_shift_g);
e3058450 ED	161	delivered_ce /= max(1U, delivered);
f9c2ff22	162
e3058450	163	alpha = min(alpha + delivered_ce, DCTCP_MAX_ALPHA);
f9c2ff22 ED	164	}
	165	/* dctcp_alpha can be read from dctcp_get_info() without
	166	* synchro, so we ask compiler to not use dctcp_alpha
	167	* as a temporary variable in prior operations.
	168	*/
	169	WRITE_ONCE(ca->dctcp_alpha, alpha);
e3118e83 DB	170	dctcp_reset(tp, ca);
	171	}
	172	}
	173
aecfde23	174	static void dctcp_react_to_loss(struct sock *sk)
e3118e83	175	{
aecfde23 KDS	176	struct dctcp *ca = inet_csk_ca(sk);
aecfde23 KDS	177	struct tcp_sock *tp = tcp_sk(sk);
e3118e83	178
40570375 ED	179	ca->loss_cwnd = tcp_snd_cwnd(tp);
40570375 ED	180	tp->snd_ssthresh = max(tcp_snd_cwnd(tp) >> 1U, 2U);
aecfde23 KDS	181	}
aecfde23 KDS	182
400031e0	183	__bpf_kfunc static void dctcp_state(struct sock *sk, u8 new_state)
aecfde23 KDS	184	{
	185	if (new_state == TCP_CA_Recovery &&
	186	new_state != inet_csk(sk)->icsk_ca_state)
	187	dctcp_react_to_loss(sk);
	188	/* We handle RTO in dctcp_cwnd_event to ensure that we perform only
	189	* one loss-adjustment per RTT.
	190	*/
e3118e83 DB	191	}
e3118e83 DB	192
400031e0	193	__bpf_kfunc static void dctcp_cwnd_event(struct sock *sk, enum tcp_ca_event ev)
e3118e83	194	{
ffd177de YC	195	struct dctcp *ca = inet_csk_ca(sk);
ffd177de YC	196
e3118e83 DB	197	switch (ev) {
e3118e83 DB	198	case CA_EVENT_ECN_IS_CE:
e3118e83	199	case CA_EVENT_ECN_NO_CE:
ffd177de	200	dctcp_ece_ack_update(sk, ev, &ca->prior_rcv_nxt, &ca->ce_state);
e3118e83	201	break;
aecfde23	202	case CA_EVENT_LOSS:
c30f8e0b	203	tcp_plb_update_state_upon_rto(sk, &ca->plb);
aecfde23 KDS	204	dctcp_react_to_loss(sk);
aecfde23 KDS	205	break;
c30f8e0b MAQ	206	case CA_EVENT_TX_START:
	207	tcp_plb_check_rehash(sk, &ca->plb); /* Maybe rehash when inflight is 0 */
	208	break;
e3118e83 DB	209	default:
	210	/* Don't care for the rest. */
	211	break;
	212	}
	213	}
	214
64f40ff5 ED	215	static size_t dctcp_get_info(struct sock sk, u32 ext, int attr,
64f40ff5 ED	216	union tcp_cc_info *info)
e3118e83 DB	217	{
e3118e83 DB	218	const struct dctcp *ca = inet_csk_ca(sk);
e3058450	219	const struct tcp_sock *tp = tcp_sk(sk);
e3118e83 DB	220
	221	/* Fill it also in case of VEGASINFO due to req struct limits.
	222	* We can still correctly retrieve it later.
	223	*/
	224	if (ext & (1 << (INET_DIAG_DCTCPINFO - 1)) \|\|
	225	ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
dcf1158b	226	memset(&info->dctcp, 0, sizeof(info->dctcp));
e3118e83	227	if (inet_csk(sk)->icsk_ca_ops != &dctcp_reno) {
64f40ff5 ED	228	info->dctcp.dctcp_enabled = 1;
	229	info->dctcp.dctcp_ce_state = (u16) ca->ce_state;
	230	info->dctcp.dctcp_alpha = ca->dctcp_alpha;
e3058450 ED	231	info->dctcp.dctcp_ab_ecn = tp->mss_cache *
	232	(tp->delivered_ce - ca->old_delivered_ce);
	233	info->dctcp.dctcp_ab_tot = tp->mss_cache *
	234	(tp->delivered - ca->old_delivered);
e3118e83 DB	235	}
e3118e83 DB	236
64f40ff5	237	*attr = INET_DIAG_DCTCPINFO;
dcf1158b	238	return sizeof(info->dctcp);
e3118e83	239	}
521f1cf1	240	return 0;
e3118e83 DB	241	}
e3118e83 DB	242
400031e0	243	__bpf_kfunc static u32 dctcp_cwnd_undo(struct sock *sk)
ce6dd233 FW	244	{
ce6dd233 FW	245	const struct dctcp *ca = inet_csk_ca(sk);
40570375	246	struct tcp_sock *tp = tcp_sk(sk);
ce6dd233	247
40570375	248	return max(tcp_snd_cwnd(tp), ca->loss_cwnd);
ce6dd233 FW	249	}
ce6dd233 FW	250
e3118e83 DB	251	static struct tcp_congestion_ops dctcp __read_mostly = {
	252	.init = dctcp_init,
	253	.in_ack_event = dctcp_update_alpha,
	254	.cwnd_event = dctcp_cwnd_event,
	255	.ssthresh = dctcp_ssthresh,
	256	.cong_avoid = tcp_reno_cong_avoid,
ce6dd233	257	.undo_cwnd = dctcp_cwnd_undo,
e3118e83 DB	258	.set_state = dctcp_state,
	259	.get_info = dctcp_get_info,
	260	.flags = TCP_CONG_NEEDS_ECN,
	261	.owner = THIS_MODULE,
	262	.name = "dctcp",
	263	};
	264
	265	static struct tcp_congestion_ops dctcp_reno __read_mostly = {
	266	.ssthresh = tcp_reno_ssthresh,
	267	.cong_avoid = tcp_reno_cong_avoid,
e9799183	268	.undo_cwnd = tcp_reno_undo_cwnd,
e3118e83 DB	269	.get_info = dctcp_get_info,
	270	.owner = THIS_MODULE,
	271	.name = "dctcp-reno",
	272	};
	273
6f3189f3	274	BTF_KFUNCS_START(tcp_dctcp_check_kfunc_ids)
a4703e31 KKD	275	BTF_ID_FLAGS(func, dctcp_init)
	276	BTF_ID_FLAGS(func, dctcp_update_alpha)
	277	BTF_ID_FLAGS(func, dctcp_cwnd_event)
	278	BTF_ID_FLAGS(func, dctcp_ssthresh)
	279	BTF_ID_FLAGS(func, dctcp_cwnd_undo)
	280	BTF_ID_FLAGS(func, dctcp_state)
6f3189f3	281	BTF_KFUNCS_END(tcp_dctcp_check_kfunc_ids)
0e32dfc8	282
b202d844	283	static const struct btf_kfunc_id_set tcp_dctcp_kfunc_set = {
a4703e31 KKD	284	.owner = THIS_MODULE,
a4703e31 KKD	285	.set = &tcp_dctcp_check_kfunc_ids,
b202d844	286	};
0e32dfc8	287
e3118e83 DB	288	static int __init dctcp_register(void)
e3118e83 DB	289	{
0e32dfc8 KKD	290	int ret;
0e32dfc8 KKD	291
e3118e83	292	BUILD_BUG_ON(sizeof(struct dctcp) > ICSK_CA_PRIV_SIZE);
b202d844 KKD	293
	294	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &tcp_dctcp_kfunc_set);
	295	if (ret < 0)
0e32dfc8	296	return ret;
b202d844	297	return tcp_register_congestion_control(&dctcp);
e3118e83 DB	298	}
	299
	300	static void __exit dctcp_unregister(void)
	301	{
	302	tcp_unregister_congestion_control(&dctcp);
	303	}
	304
	305	module_init(dctcp_register);
	306	module_exit(dctcp_unregister);
	307
	308	MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
	309	MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
	310	MODULE_AUTHOR("Glenn Judd <glenn.judd@morganstanley.com>");
	311
	312	MODULE_LICENSE("GPL v2");
	313	MODULE_DESCRIPTION("DataCenter TCP (DCTCP)");