[DCCP]: Simplified conditions due to use of enum:8 states
[linux-2.6.git] / net / dccp / ccids / lib / loss_interval.c
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
19 struct 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;
40 out:
41         return hist;
42 out_free_slab_name:
43         kfree(slab_name);
44 out_free_hist:
45         kfree(hist);
46         hist = NULL;
47         goto out;
48 }
49
50 EXPORT_SYMBOL_GPL(dccp_li_hist_new);
51
52 void 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
61 EXPORT_SYMBOL_GPL(dccp_li_hist_delete);
62
63 void 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
73 EXPORT_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  */
80 static const int dccp_li_hist_w[DCCP_LI_HIST_IVAL_F_LENGTH] = {
81         4, 4, 4, 4, 3, 2, 1, 1,
82 };
83
84 u32 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 != ~0) {
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
119 EXPORT_SYMBOL_GPL(dccp_li_hist_calc_i_mean);
120
121 int 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, SLAB_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
143 EXPORT_SYMBOL_GPL(dccp_li_hist_interval_new);