1/*
2 *  net/dccp/ccids/lib/loss_interval.c
3 *
4 *  Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
5 *  Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
6 *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7 *
8 *  This program is free software; you can redistribute it and/or modify
9 *  it under the terms of the GNU General Public License as published by
10 *  the Free Software Foundation; either version 2 of the License, or
11 *  (at your option) any later version.
12 */
13
14#include <linux/module.h>
15#include <net/sock.h>
16#include "../../dccp.h"
17#include "loss_interval.h"
18
19struct dccp_li_hist *dccp_li_hist_new(const char *name)
20{
21	struct dccp_li_hist *hist = kmalloc(sizeof(*hist), GFP_ATOMIC);
22	static const char dccp_li_hist_mask[] = "li_hist_%s";
23	char *slab_name;
24
25	if (hist == NULL)
26		goto out;
27
28	slab_name = kmalloc(strlen(name) + sizeof(dccp_li_hist_mask) - 1,
29			    GFP_ATOMIC);
30	if (slab_name == NULL)
31		goto out_free_hist;
32
33	sprintf(slab_name, dccp_li_hist_mask, name);
34	hist->dccplih_slab = kmem_cache_create(slab_name,
35					     sizeof(struct dccp_li_hist_entry),
36					       0, SLAB_HWCACHE_ALIGN,
37					       NULL, NULL);
38	if (hist->dccplih_slab == NULL)
39		goto out_free_slab_name;
40out:
41	return hist;
42out_free_slab_name:
43	kfree(slab_name);
44out_free_hist:
45	kfree(hist);
46	hist = NULL;
47	goto out;
48}
49
50EXPORT_SYMBOL_GPL(dccp_li_hist_new);
51
52void dccp_li_hist_delete(struct dccp_li_hist *hist)
53{
54	const char* name = kmem_cache_name(hist->dccplih_slab);
55
56	kmem_cache_destroy(hist->dccplih_slab);
57	kfree(name);
58	kfree(hist);
59}
60
61EXPORT_SYMBOL_GPL(dccp_li_hist_delete);
62
63void dccp_li_hist_purge(struct dccp_li_hist *hist, struct list_head *list)
64{
65	struct dccp_li_hist_entry *entry, *next;
66
67	list_for_each_entry_safe(entry, next, list, dccplih_node) {
68		list_del_init(&entry->dccplih_node);
69		kmem_cache_free(hist->dccplih_slab, entry);
70	}
71}
72
73EXPORT_SYMBOL_GPL(dccp_li_hist_purge);
74
75/* Weights used to calculate loss event rate */
76/*
77 * These are integers as per section 8 of RFC3448. We can then divide by 4 *
78 * when we use it.
79 */
80static const int dccp_li_hist_w[DCCP_LI_HIST_IVAL_F_LENGTH] = {
81	4, 4, 4, 4, 3, 2, 1, 1,
82};
83
84u32 dccp_li_hist_calc_i_mean(struct list_head *list)
85{
86	struct dccp_li_hist_entry *li_entry, *li_next;
87	int i = 0;
88	u32 i_tot;
89	u32 i_tot0 = 0;
90	u32 i_tot1 = 0;
91	u32 w_tot  = 0;
92
93	list_for_each_entry_safe(li_entry, li_next, list, dccplih_node) {
94		if (li_entry->dccplih_interval != ~0U) {
95			i_tot0 += li_entry->dccplih_interval * dccp_li_hist_w[i];
96			w_tot  += dccp_li_hist_w[i];
97			if (i != 0)
98				i_tot1 += li_entry->dccplih_interval * dccp_li_hist_w[i - 1];
99		}
100
101
102		if (++i > DCCP_LI_HIST_IVAL_F_LENGTH)
103			break;
104	}
105
106	if (i != DCCP_LI_HIST_IVAL_F_LENGTH)
107		return 0;
108
109	i_tot = max(i_tot0, i_tot1);
110
111	if (!w_tot) {
112		DCCP_WARN("w_tot = 0\n");
113		return 1;
114	}
115
116	return i_tot / w_tot;
117}
118
119EXPORT_SYMBOL_GPL(dccp_li_hist_calc_i_mean);
120
121int dccp_li_hist_interval_new(struct dccp_li_hist *hist,
122   struct list_head *list, const u64 seq_loss, const u8 win_loss)
123{
124	struct dccp_li_hist_entry *entry;
125	int i;
126
127	for (i = 0; i < DCCP_LI_HIST_IVAL_F_LENGTH; i++) {
128		entry = dccp_li_hist_entry_new(hist, GFP_ATOMIC);
129		if (entry == NULL) {
130			dccp_li_hist_purge(hist, list);
131			DCCP_BUG("loss interval list entry is NULL");
132			return 0;
133		}
134		entry->dccplih_interval = ~0;
135		list_add(&entry->dccplih_node, list);
136	}
137
138	entry->dccplih_seqno     = seq_loss;
139	entry->dccplih_win_count = win_loss;
140	return 1;
141}
142
143EXPORT_SYMBOL_GPL(dccp_li_hist_interval_new);
144