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   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);