Merge master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-for-linus-2.6
[linux-2.6] / 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 Ian McDonald <iam4@cs.waikato.ac.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/config.h>
15 #include <linux/module.h>
16
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 (i < DCCP_LI_HIST_IVAL_F_LENGTH) {
95                         i_tot0 += li_entry->dccplih_interval * dccp_li_hist_w[i];
96                         w_tot  += dccp_li_hist_w[i];
97                 }
98
99                 if (i != 0)
100                         i_tot1 += li_entry->dccplih_interval * dccp_li_hist_w[i - 1];
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         /* FIXME: Why do we do this? -Ian McDonald */
112         if (i_tot * 4 < w_tot)
113                 i_tot = w_tot * 4;
114
115         return i_tot * 4 / w_tot;
116 }
117
118 EXPORT_SYMBOL_GPL(dccp_li_hist_calc_i_mean);
119
120 struct dccp_li_hist_entry *dccp_li_hist_interval_new(struct dccp_li_hist *hist,
121                                                      struct list_head *list,
122                                                      const u64 seq_loss,
123                                                      const u8 win_loss)
124 {
125         struct dccp_li_hist_entry *tail = NULL, *entry;
126         int i;
127
128         for (i = 0; i <= DCCP_LI_HIST_IVAL_F_LENGTH; ++i) {
129                 entry = dccp_li_hist_entry_new(hist, SLAB_ATOMIC);
130                 if (entry == NULL) {
131                         dccp_li_hist_purge(hist, list);
132                         return NULL;
133                 }
134                 if (tail == NULL)
135                         tail = entry;
136                 list_add(&entry->dccplih_node, list);
137         }
138
139         entry->dccplih_seqno     = seq_loss;
140         entry->dccplih_win_count = win_loss;
141         return tail;
142 }
143
144 EXPORT_SYMBOL_GPL(dccp_li_hist_interval_new);