xref: /openbmc/linux/net/dccp/ccids/lib/loss_interval.c (revision cc0a910b942d11069d35f52b2c0ed0e229e2fb46)
1ae6706f0SArnaldo Carvalho de Melo /*
2ae6706f0SArnaldo Carvalho de Melo  *  net/dccp/ccids/lib/loss_interval.c
3ae6706f0SArnaldo Carvalho de Melo  *
4b2f41ff4SIan McDonald  *  Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
5b2f41ff4SIan McDonald  *  Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
6ae6706f0SArnaldo Carvalho de Melo  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7ae6706f0SArnaldo Carvalho de Melo  *
8ae6706f0SArnaldo Carvalho de Melo  *  This program is free software; you can redistribute it and/or modify
9ae6706f0SArnaldo Carvalho de Melo  *  it under the terms of the GNU General Public License as published by
10ae6706f0SArnaldo Carvalho de Melo  *  the Free Software Foundation; either version 2 of the License, or
11ae6706f0SArnaldo Carvalho de Melo  *  (at your option) any later version.
12ae6706f0SArnaldo Carvalho de Melo  */
13ae6706f0SArnaldo Carvalho de Melo 
14ae6706f0SArnaldo Carvalho de Melo #include <linux/module.h>
1566a377c5SIan McDonald #include <net/sock.h>
1659348b19SGerrit Renker #include "../../dccp.h"
17ae6706f0SArnaldo Carvalho de Melo #include "loss_interval.h"
18*cc0a910bSArnaldo Carvalho de Melo #include "packet_history.h"
19*cc0a910bSArnaldo Carvalho de Melo #include "tfrc.h"
20ae6706f0SArnaldo Carvalho de Melo 
21ae6706f0SArnaldo Carvalho de Melo struct dccp_li_hist *dccp_li_hist_new(const char *name)
22ae6706f0SArnaldo Carvalho de Melo {
23ae6706f0SArnaldo Carvalho de Melo 	struct dccp_li_hist *hist = kmalloc(sizeof(*hist), GFP_ATOMIC);
24ae6706f0SArnaldo Carvalho de Melo 	static const char dccp_li_hist_mask[] = "li_hist_%s";
25ae6706f0SArnaldo Carvalho de Melo 	char *slab_name;
26ae6706f0SArnaldo Carvalho de Melo 
27ae6706f0SArnaldo Carvalho de Melo 	if (hist == NULL)
28ae6706f0SArnaldo Carvalho de Melo 		goto out;
29ae6706f0SArnaldo Carvalho de Melo 
30ae6706f0SArnaldo Carvalho de Melo 	slab_name = kmalloc(strlen(name) + sizeof(dccp_li_hist_mask) - 1,
31ae6706f0SArnaldo Carvalho de Melo 			    GFP_ATOMIC);
32ae6706f0SArnaldo Carvalho de Melo 	if (slab_name == NULL)
33ae6706f0SArnaldo Carvalho de Melo 		goto out_free_hist;
34ae6706f0SArnaldo Carvalho de Melo 
35ae6706f0SArnaldo Carvalho de Melo 	sprintf(slab_name, dccp_li_hist_mask, name);
36ae6706f0SArnaldo Carvalho de Melo 	hist->dccplih_slab = kmem_cache_create(slab_name,
37ae6706f0SArnaldo Carvalho de Melo 					     sizeof(struct dccp_li_hist_entry),
38ae6706f0SArnaldo Carvalho de Melo 					       0, SLAB_HWCACHE_ALIGN,
39ae6706f0SArnaldo Carvalho de Melo 					       NULL, NULL);
40ae6706f0SArnaldo Carvalho de Melo 	if (hist->dccplih_slab == NULL)
41ae6706f0SArnaldo Carvalho de Melo 		goto out_free_slab_name;
42ae6706f0SArnaldo Carvalho de Melo out:
43ae6706f0SArnaldo Carvalho de Melo 	return hist;
44ae6706f0SArnaldo Carvalho de Melo out_free_slab_name:
45ae6706f0SArnaldo Carvalho de Melo 	kfree(slab_name);
46ae6706f0SArnaldo Carvalho de Melo out_free_hist:
47ae6706f0SArnaldo Carvalho de Melo 	kfree(hist);
48ae6706f0SArnaldo Carvalho de Melo 	hist = NULL;
49ae6706f0SArnaldo Carvalho de Melo 	goto out;
50ae6706f0SArnaldo Carvalho de Melo }
51ae6706f0SArnaldo Carvalho de Melo 
52ae6706f0SArnaldo Carvalho de Melo EXPORT_SYMBOL_GPL(dccp_li_hist_new);
53ae6706f0SArnaldo Carvalho de Melo 
54ae6706f0SArnaldo Carvalho de Melo void dccp_li_hist_delete(struct dccp_li_hist *hist)
55ae6706f0SArnaldo Carvalho de Melo {
56ae6706f0SArnaldo Carvalho de Melo 	const char* name = kmem_cache_name(hist->dccplih_slab);
57ae6706f0SArnaldo Carvalho de Melo 
58ae6706f0SArnaldo Carvalho de Melo 	kmem_cache_destroy(hist->dccplih_slab);
59ae6706f0SArnaldo Carvalho de Melo 	kfree(name);
60ae6706f0SArnaldo Carvalho de Melo 	kfree(hist);
61ae6706f0SArnaldo Carvalho de Melo }
62ae6706f0SArnaldo Carvalho de Melo 
63ae6706f0SArnaldo Carvalho de Melo EXPORT_SYMBOL_GPL(dccp_li_hist_delete);
64ae6706f0SArnaldo Carvalho de Melo 
65ae6706f0SArnaldo Carvalho de Melo void dccp_li_hist_purge(struct dccp_li_hist *hist, struct list_head *list)
66ae6706f0SArnaldo Carvalho de Melo {
67ae6706f0SArnaldo Carvalho de Melo 	struct dccp_li_hist_entry *entry, *next;
68ae6706f0SArnaldo Carvalho de Melo 
69ae6706f0SArnaldo Carvalho de Melo 	list_for_each_entry_safe(entry, next, list, dccplih_node) {
70ae6706f0SArnaldo Carvalho de Melo 		list_del_init(&entry->dccplih_node);
71ae6706f0SArnaldo Carvalho de Melo 		kmem_cache_free(hist->dccplih_slab, entry);
72ae6706f0SArnaldo Carvalho de Melo 	}
73ae6706f0SArnaldo Carvalho de Melo }
74ae6706f0SArnaldo Carvalho de Melo 
75ae6706f0SArnaldo Carvalho de Melo EXPORT_SYMBOL_GPL(dccp_li_hist_purge);
76ae6706f0SArnaldo Carvalho de Melo 
77ae6706f0SArnaldo Carvalho de Melo /* Weights used to calculate loss event rate */
78ae6706f0SArnaldo Carvalho de Melo /*
79ae6706f0SArnaldo Carvalho de Melo  * These are integers as per section 8 of RFC3448. We can then divide by 4 *
80ae6706f0SArnaldo Carvalho de Melo  * when we use it.
81ae6706f0SArnaldo Carvalho de Melo  */
82ae6706f0SArnaldo Carvalho de Melo static const int dccp_li_hist_w[DCCP_LI_HIST_IVAL_F_LENGTH] = {
83ae6706f0SArnaldo Carvalho de Melo 	4, 4, 4, 4, 3, 2, 1, 1,
84ae6706f0SArnaldo Carvalho de Melo };
85ae6706f0SArnaldo Carvalho de Melo 
86ae6706f0SArnaldo Carvalho de Melo u32 dccp_li_hist_calc_i_mean(struct list_head *list)
87ae6706f0SArnaldo Carvalho de Melo {
88ae6706f0SArnaldo Carvalho de Melo 	struct dccp_li_hist_entry *li_entry, *li_next;
89ae6706f0SArnaldo Carvalho de Melo 	int i = 0;
90ae6706f0SArnaldo Carvalho de Melo 	u32 i_tot;
91ae6706f0SArnaldo Carvalho de Melo 	u32 i_tot0 = 0;
92ae6706f0SArnaldo Carvalho de Melo 	u32 i_tot1 = 0;
93ae6706f0SArnaldo Carvalho de Melo 	u32 w_tot  = 0;
94ae6706f0SArnaldo Carvalho de Melo 
95ae6706f0SArnaldo Carvalho de Melo 	list_for_each_entry_safe(li_entry, li_next, list, dccplih_node) {
96551dc5f7SIan McDonald 		if (li_entry->dccplih_interval != ~0U) {
97ae6706f0SArnaldo Carvalho de Melo 			i_tot0 += li_entry->dccplih_interval * dccp_li_hist_w[i];
98ae6706f0SArnaldo Carvalho de Melo 			w_tot  += dccp_li_hist_w[i];
99ae6706f0SArnaldo Carvalho de Melo 			if (i != 0)
100ae6706f0SArnaldo Carvalho de Melo 				i_tot1 += li_entry->dccplih_interval * dccp_li_hist_w[i - 1];
10166a377c5SIan McDonald 		}
10266a377c5SIan McDonald 
103ae6706f0SArnaldo Carvalho de Melo 
104ae6706f0SArnaldo Carvalho de Melo 		if (++i > DCCP_LI_HIST_IVAL_F_LENGTH)
105ae6706f0SArnaldo Carvalho de Melo 			break;
106ae6706f0SArnaldo Carvalho de Melo 	}
107ae6706f0SArnaldo Carvalho de Melo 
108ae6706f0SArnaldo Carvalho de Melo 	if (i != DCCP_LI_HIST_IVAL_F_LENGTH)
109ae6706f0SArnaldo Carvalho de Melo 		return 0;
110ae6706f0SArnaldo Carvalho de Melo 
111ae6706f0SArnaldo Carvalho de Melo 	i_tot = max(i_tot0, i_tot1);
112ae6706f0SArnaldo Carvalho de Melo 
11366a377c5SIan McDonald 	if (!w_tot) {
11459348b19SGerrit Renker 		DCCP_WARN("w_tot = 0\n");
11566a377c5SIan McDonald 		return 1;
11666a377c5SIan McDonald 	}
117ae6706f0SArnaldo Carvalho de Melo 
11866a377c5SIan McDonald 	return i_tot / w_tot;
119ae6706f0SArnaldo Carvalho de Melo }
120ae6706f0SArnaldo Carvalho de Melo 
121ae6706f0SArnaldo Carvalho de Melo EXPORT_SYMBOL_GPL(dccp_li_hist_calc_i_mean);
122ae6706f0SArnaldo Carvalho de Melo 
12366a377c5SIan McDonald int dccp_li_hist_interval_new(struct dccp_li_hist *hist,
12466a377c5SIan McDonald    struct list_head *list, const u64 seq_loss, const u8 win_loss)
125ae6706f0SArnaldo Carvalho de Melo {
12666a377c5SIan McDonald 	struct dccp_li_hist_entry *entry;
127ae6706f0SArnaldo Carvalho de Melo 	int i;
128ae6706f0SArnaldo Carvalho de Melo 
12966a377c5SIan McDonald 	for (i = 0; i < DCCP_LI_HIST_IVAL_F_LENGTH; i++) {
13054e6ecb2SChristoph Lameter 		entry = dccp_li_hist_entry_new(hist, GFP_ATOMIC);
131ae6706f0SArnaldo Carvalho de Melo 		if (entry == NULL) {
132ae6706f0SArnaldo Carvalho de Melo 			dccp_li_hist_purge(hist, list);
13359348b19SGerrit Renker 			DCCP_BUG("loss interval list entry is NULL");
13466a377c5SIan McDonald 			return 0;
135ae6706f0SArnaldo Carvalho de Melo 		}
13666a377c5SIan McDonald 		entry->dccplih_interval = ~0;
137ae6706f0SArnaldo Carvalho de Melo 		list_add(&entry->dccplih_node, list);
138ae6706f0SArnaldo Carvalho de Melo 	}
139ae6706f0SArnaldo Carvalho de Melo 
140ae6706f0SArnaldo Carvalho de Melo 	entry->dccplih_seqno     = seq_loss;
141ae6706f0SArnaldo Carvalho de Melo 	entry->dccplih_win_count = win_loss;
14266a377c5SIan McDonald 	return 1;
143ae6706f0SArnaldo Carvalho de Melo }
144ae6706f0SArnaldo Carvalho de Melo 
145ae6706f0SArnaldo Carvalho de Melo EXPORT_SYMBOL_GPL(dccp_li_hist_interval_new);
146*cc0a910bSArnaldo Carvalho de Melo 
147*cc0a910bSArnaldo Carvalho de Melo /* calculate first loss interval
148*cc0a910bSArnaldo Carvalho de Melo  *
149*cc0a910bSArnaldo Carvalho de Melo  * returns estimated loss interval in usecs */
150*cc0a910bSArnaldo Carvalho de Melo static u32 dccp_li_calc_first_li(struct sock *sk,
151*cc0a910bSArnaldo Carvalho de Melo 				 struct list_head *hist_list,
152*cc0a910bSArnaldo Carvalho de Melo 				 struct timeval *last_feedback,
153*cc0a910bSArnaldo Carvalho de Melo 				 u16 s, u32 bytes_recv,
154*cc0a910bSArnaldo Carvalho de Melo 				 u32 previous_x_recv)
155*cc0a910bSArnaldo Carvalho de Melo {
156*cc0a910bSArnaldo Carvalho de Melo 	struct dccp_rx_hist_entry *entry, *next, *tail = NULL;
157*cc0a910bSArnaldo Carvalho de Melo 	u32 x_recv, p;
158*cc0a910bSArnaldo Carvalho de Melo 	suseconds_t rtt, delta;
159*cc0a910bSArnaldo Carvalho de Melo 	struct timeval tstamp = { 0, 0 };
160*cc0a910bSArnaldo Carvalho de Melo 	int interval = 0;
161*cc0a910bSArnaldo Carvalho de Melo 	int win_count = 0;
162*cc0a910bSArnaldo Carvalho de Melo 	int step = 0;
163*cc0a910bSArnaldo Carvalho de Melo 	u64 fval;
164*cc0a910bSArnaldo Carvalho de Melo 
165*cc0a910bSArnaldo Carvalho de Melo 	list_for_each_entry_safe(entry, next, hist_list, dccphrx_node) {
166*cc0a910bSArnaldo Carvalho de Melo 		if (dccp_rx_hist_entry_data_packet(entry)) {
167*cc0a910bSArnaldo Carvalho de Melo 			tail = entry;
168*cc0a910bSArnaldo Carvalho de Melo 
169*cc0a910bSArnaldo Carvalho de Melo 			switch (step) {
170*cc0a910bSArnaldo Carvalho de Melo 			case 0:
171*cc0a910bSArnaldo Carvalho de Melo 				tstamp	  = entry->dccphrx_tstamp;
172*cc0a910bSArnaldo Carvalho de Melo 				win_count = entry->dccphrx_ccval;
173*cc0a910bSArnaldo Carvalho de Melo 				step = 1;
174*cc0a910bSArnaldo Carvalho de Melo 				break;
175*cc0a910bSArnaldo Carvalho de Melo 			case 1:
176*cc0a910bSArnaldo Carvalho de Melo 				interval = win_count - entry->dccphrx_ccval;
177*cc0a910bSArnaldo Carvalho de Melo 				if (interval < 0)
178*cc0a910bSArnaldo Carvalho de Melo 					interval += TFRC_WIN_COUNT_LIMIT;
179*cc0a910bSArnaldo Carvalho de Melo 				if (interval > 4)
180*cc0a910bSArnaldo Carvalho de Melo 					goto found;
181*cc0a910bSArnaldo Carvalho de Melo 				break;
182*cc0a910bSArnaldo Carvalho de Melo 			}
183*cc0a910bSArnaldo Carvalho de Melo 		}
184*cc0a910bSArnaldo Carvalho de Melo 	}
185*cc0a910bSArnaldo Carvalho de Melo 
186*cc0a910bSArnaldo Carvalho de Melo 	if (unlikely(step == 0)) {
187*cc0a910bSArnaldo Carvalho de Melo 		DCCP_WARN("%s(%p), packet history has no data packets!\n",
188*cc0a910bSArnaldo Carvalho de Melo 			  dccp_role(sk), sk);
189*cc0a910bSArnaldo Carvalho de Melo 		return ~0;
190*cc0a910bSArnaldo Carvalho de Melo 	}
191*cc0a910bSArnaldo Carvalho de Melo 
192*cc0a910bSArnaldo Carvalho de Melo 	if (unlikely(interval == 0)) {
193*cc0a910bSArnaldo Carvalho de Melo 		DCCP_WARN("%s(%p), Could not find a win_count interval > 0."
194*cc0a910bSArnaldo Carvalho de Melo 			  "Defaulting to 1\n", dccp_role(sk), sk);
195*cc0a910bSArnaldo Carvalho de Melo 		interval = 1;
196*cc0a910bSArnaldo Carvalho de Melo 	}
197*cc0a910bSArnaldo Carvalho de Melo found:
198*cc0a910bSArnaldo Carvalho de Melo 	if (!tail) {
199*cc0a910bSArnaldo Carvalho de Melo 		DCCP_CRIT("tail is null\n");
200*cc0a910bSArnaldo Carvalho de Melo 		return ~0;
201*cc0a910bSArnaldo Carvalho de Melo 	}
202*cc0a910bSArnaldo Carvalho de Melo 
203*cc0a910bSArnaldo Carvalho de Melo 	delta = timeval_delta(&tstamp, &tail->dccphrx_tstamp);
204*cc0a910bSArnaldo Carvalho de Melo 	DCCP_BUG_ON(delta < 0);
205*cc0a910bSArnaldo Carvalho de Melo 
206*cc0a910bSArnaldo Carvalho de Melo 	rtt = delta * 4 / interval;
207*cc0a910bSArnaldo Carvalho de Melo 	dccp_pr_debug("%s(%p), approximated RTT to %dus\n",
208*cc0a910bSArnaldo Carvalho de Melo 		      dccp_role(sk), sk, (int)rtt);
209*cc0a910bSArnaldo Carvalho de Melo 
210*cc0a910bSArnaldo Carvalho de Melo 	/*
211*cc0a910bSArnaldo Carvalho de Melo 	 * Determine the length of the first loss interval via inverse lookup.
212*cc0a910bSArnaldo Carvalho de Melo 	 * Assume that X_recv can be computed by the throughput equation
213*cc0a910bSArnaldo Carvalho de Melo 	 *		    s
214*cc0a910bSArnaldo Carvalho de Melo 	 *	X_recv = --------
215*cc0a910bSArnaldo Carvalho de Melo 	 *		 R * fval
216*cc0a910bSArnaldo Carvalho de Melo 	 * Find some p such that f(p) = fval; return 1/p [RFC 3448, 6.3.1].
217*cc0a910bSArnaldo Carvalho de Melo 	 */
218*cc0a910bSArnaldo Carvalho de Melo 	if (rtt == 0) {			/* would result in divide-by-zero */
219*cc0a910bSArnaldo Carvalho de Melo 		DCCP_WARN("RTT==0\n");
220*cc0a910bSArnaldo Carvalho de Melo 		return ~0;
221*cc0a910bSArnaldo Carvalho de Melo 	}
222*cc0a910bSArnaldo Carvalho de Melo 
223*cc0a910bSArnaldo Carvalho de Melo 	dccp_timestamp(sk, &tstamp);
224*cc0a910bSArnaldo Carvalho de Melo 	delta = timeval_delta(&tstamp, last_feedback);
225*cc0a910bSArnaldo Carvalho de Melo 	DCCP_BUG_ON(delta <= 0);
226*cc0a910bSArnaldo Carvalho de Melo 
227*cc0a910bSArnaldo Carvalho de Melo 	x_recv = scaled_div32(bytes_recv, delta);
228*cc0a910bSArnaldo Carvalho de Melo 	if (x_recv == 0) {		/* would also trigger divide-by-zero */
229*cc0a910bSArnaldo Carvalho de Melo 		DCCP_WARN("X_recv==0\n");
230*cc0a910bSArnaldo Carvalho de Melo 		if (previous_x_recv == 0) {
231*cc0a910bSArnaldo Carvalho de Melo 			DCCP_BUG("stored value of X_recv is zero");
232*cc0a910bSArnaldo Carvalho de Melo 			return ~0;
233*cc0a910bSArnaldo Carvalho de Melo 		}
234*cc0a910bSArnaldo Carvalho de Melo 		x_recv = previous_x_recv;
235*cc0a910bSArnaldo Carvalho de Melo 	}
236*cc0a910bSArnaldo Carvalho de Melo 
237*cc0a910bSArnaldo Carvalho de Melo 	fval = scaled_div(s, rtt);
238*cc0a910bSArnaldo Carvalho de Melo 	fval = scaled_div32(fval, x_recv);
239*cc0a910bSArnaldo Carvalho de Melo 	p = tfrc_calc_x_reverse_lookup(fval);
240*cc0a910bSArnaldo Carvalho de Melo 
241*cc0a910bSArnaldo Carvalho de Melo 	dccp_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
242*cc0a910bSArnaldo Carvalho de Melo 		      "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
243*cc0a910bSArnaldo Carvalho de Melo 
244*cc0a910bSArnaldo Carvalho de Melo 	if (p == 0)
245*cc0a910bSArnaldo Carvalho de Melo 		return ~0;
246*cc0a910bSArnaldo Carvalho de Melo 	else
247*cc0a910bSArnaldo Carvalho de Melo 		return 1000000 / p;
248*cc0a910bSArnaldo Carvalho de Melo }
249*cc0a910bSArnaldo Carvalho de Melo 
250*cc0a910bSArnaldo Carvalho de Melo void dccp_li_update_li(struct sock *sk, struct dccp_li_hist *li_hist,
251*cc0a910bSArnaldo Carvalho de Melo 		       struct list_head *li_hist_list,
252*cc0a910bSArnaldo Carvalho de Melo 		       struct list_head *hist_list,
253*cc0a910bSArnaldo Carvalho de Melo 		       struct timeval *last_feedback, u16 s, u32 bytes_recv,
254*cc0a910bSArnaldo Carvalho de Melo                        u32 previous_x_recv, u64 seq_loss, u8 win_loss)
255*cc0a910bSArnaldo Carvalho de Melo {
256*cc0a910bSArnaldo Carvalho de Melo 	struct dccp_li_hist_entry *head;
257*cc0a910bSArnaldo Carvalho de Melo 	u64 seq_temp;
258*cc0a910bSArnaldo Carvalho de Melo 
259*cc0a910bSArnaldo Carvalho de Melo 	if (list_empty(li_hist_list)) {
260*cc0a910bSArnaldo Carvalho de Melo 		if (!dccp_li_hist_interval_new(li_hist, li_hist_list,
261*cc0a910bSArnaldo Carvalho de Melo 					       seq_loss, win_loss))
262*cc0a910bSArnaldo Carvalho de Melo 			return;
263*cc0a910bSArnaldo Carvalho de Melo 
264*cc0a910bSArnaldo Carvalho de Melo 		head = list_entry(li_hist_list->next, struct dccp_li_hist_entry,
265*cc0a910bSArnaldo Carvalho de Melo 				  dccplih_node);
266*cc0a910bSArnaldo Carvalho de Melo 		head->dccplih_interval = dccp_li_calc_first_li(sk, hist_list,
267*cc0a910bSArnaldo Carvalho de Melo 							       last_feedback,
268*cc0a910bSArnaldo Carvalho de Melo 							       s, bytes_recv,
269*cc0a910bSArnaldo Carvalho de Melo 							       previous_x_recv);
270*cc0a910bSArnaldo Carvalho de Melo 	} else {
271*cc0a910bSArnaldo Carvalho de Melo 		struct dccp_li_hist_entry *entry;
272*cc0a910bSArnaldo Carvalho de Melo 		struct list_head *tail;
273*cc0a910bSArnaldo Carvalho de Melo 
274*cc0a910bSArnaldo Carvalho de Melo 		head = list_entry(li_hist_list->next, struct dccp_li_hist_entry,
275*cc0a910bSArnaldo Carvalho de Melo 				  dccplih_node);
276*cc0a910bSArnaldo Carvalho de Melo 		/* FIXME win count check removed as was wrong */
277*cc0a910bSArnaldo Carvalho de Melo 		/* should make this check with receive history */
278*cc0a910bSArnaldo Carvalho de Melo 		/* and compare there as per section 10.2 of RFC4342 */
279*cc0a910bSArnaldo Carvalho de Melo 
280*cc0a910bSArnaldo Carvalho de Melo 		/* new loss event detected */
281*cc0a910bSArnaldo Carvalho de Melo 		/* calculate last interval length */
282*cc0a910bSArnaldo Carvalho de Melo 		seq_temp = dccp_delta_seqno(head->dccplih_seqno, seq_loss);
283*cc0a910bSArnaldo Carvalho de Melo 		entry = dccp_li_hist_entry_new(li_hist, GFP_ATOMIC);
284*cc0a910bSArnaldo Carvalho de Melo 
285*cc0a910bSArnaldo Carvalho de Melo 		if (entry == NULL) {
286*cc0a910bSArnaldo Carvalho de Melo 			DCCP_BUG("out of memory - can not allocate entry");
287*cc0a910bSArnaldo Carvalho de Melo 			return;
288*cc0a910bSArnaldo Carvalho de Melo 		}
289*cc0a910bSArnaldo Carvalho de Melo 
290*cc0a910bSArnaldo Carvalho de Melo 		list_add(&entry->dccplih_node, li_hist_list);
291*cc0a910bSArnaldo Carvalho de Melo 
292*cc0a910bSArnaldo Carvalho de Melo 		tail = li_hist_list->prev;
293*cc0a910bSArnaldo Carvalho de Melo 		list_del(tail);
294*cc0a910bSArnaldo Carvalho de Melo 		kmem_cache_free(li_hist->dccplih_slab, tail);
295*cc0a910bSArnaldo Carvalho de Melo 
296*cc0a910bSArnaldo Carvalho de Melo 		/* Create the newest interval */
297*cc0a910bSArnaldo Carvalho de Melo 		entry->dccplih_seqno = seq_loss;
298*cc0a910bSArnaldo Carvalho de Melo 		entry->dccplih_interval = seq_temp;
299*cc0a910bSArnaldo Carvalho de Melo 		entry->dccplih_win_count = win_loss;
300*cc0a910bSArnaldo Carvalho de Melo 	}
301*cc0a910bSArnaldo Carvalho de Melo }
302*cc0a910bSArnaldo Carvalho de Melo 
303*cc0a910bSArnaldo Carvalho de Melo EXPORT_SYMBOL_GPL(dccp_li_update_li);
304