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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/module.h>
  15
  16 #include "loss_interval.h"
  17
  18 struct dccp_li_hist *dccp_li_hist_new(const char *name)
  19 {
  20         struct dccp_li_hist *hist = kmalloc(sizeof(*hist), GFP_ATOMIC);
  21         static const char dccp_li_hist_mask[] = "li_hist_%s";
  22         char *slab_name;
  23
  24         if (hist == NULL)
  25                 goto out;
  26
  27         slab_name = kmalloc(strlen(name) + sizeof(dccp_li_hist_mask) - 1,
  28                             GFP_ATOMIC);
  29         if (slab_name == NULL)
  30                 goto out_free_hist;
  31
  32         sprintf(slab_name, dccp_li_hist_mask, name);
  33         hist->dccplih_slab = kmem_cache_create(slab_name,
  34                                              sizeof(struct dccp_li_hist_entry),
  35                                                0, SLAB_HWCACHE_ALIGN,
  36                                                NULL, NULL);
  37         if (hist->dccplih_slab == NULL)
  38                 goto out_free_slab_name;
  39 out:
  40         return hist;
  41 out_free_slab_name:
  42         kfree(slab_name);
  43 out_free_hist:
  44         kfree(hist);
  45         hist = NULL;
  46         goto out;
  47 }
  48
  49 EXPORT_SYMBOL_GPL(dccp_li_hist_new);
  50
  51 void dccp_li_hist_delete(struct dccp_li_hist *hist)
  52 {
  53         const char* name = kmem_cache_name(hist->dccplih_slab);
  54
  55         kmem_cache_destroy(hist->dccplih_slab);
  56         kfree(name);
  57         kfree(hist);
  58 }
  59
  60 EXPORT_SYMBOL_GPL(dccp_li_hist_delete);
  61
  62 void dccp_li_hist_purge(struct dccp_li_hist *hist, struct list_head *list)
  63 {
  64         struct dccp_li_hist_entry *entry, *next;
  65
  66         list_for_each_entry_safe(entry, next, list, dccplih_node) {
  67                 list_del_init(&entry->dccplih_node);
  68                 kmem_cache_free(hist->dccplih_slab, entry);
  69         }
  70 }
  71
  72 EXPORT_SYMBOL_GPL(dccp_li_hist_purge);
  73
  74 /* Weights used to calculate loss event rate */
  75 /*
  76  * These are integers as per section 8 of RFC3448. We can then divide by 4 *
  77  * when we use it.
  78  */
  79 static const int dccp_li_hist_w[DCCP_LI_HIST_IVAL_F_LENGTH] = {
  80         4, 4, 4, 4, 3, 2, 1, 1,
  81 };
  82
  83 u32 dccp_li_hist_calc_i_mean(struct list_head *list)
  84 {
  85         struct dccp_li_hist_entry *li_entry, *li_next;
  86         int i = 0;
  87         u32 i_tot;
  88         u32 i_tot0 = 0;
  89         u32 i_tot1 = 0;
  90         u32 w_tot  = 0;
  91
  92         list_for_each_entry_safe(li_entry, li_next, list, dccplih_node) {
  93                 if (i < DCCP_LI_HIST_IVAL_F_LENGTH) {
  94                         i_tot0 += li_entry->dccplih_interval * dccp_li_hist_w[i];
  95                         w_tot  += dccp_li_hist_w[i];
  96                 }
  97
  98                 if (i != 0)
  99                         i_tot1 += li_entry->dccplih_interval * dccp_li_hist_w[i - 1];
 100
 101                 if (++i > DCCP_LI_HIST_IVAL_F_LENGTH)
 102                         break;
 103         }
 104
 105         if (i != DCCP_LI_HIST_IVAL_F_LENGTH)
 106                 return 0;
 107
 108         i_tot = max(i_tot0, i_tot1);
 109
 110         /* FIXME: Why do we do this? -Ian McDonald */
 111         if (i_tot * 4 < w_tot)
 112                 i_tot = w_tot * 4;
 113
 114         return i_tot * 4 / w_tot;
 115 }
 116
 117 EXPORT_SYMBOL_GPL(dccp_li_hist_calc_i_mean);
 118
 119 struct dccp_li_hist_entry *dccp_li_hist_interval_new(struct dccp_li_hist *hist,
 120                                                      struct list_head *list,
 121                                                      const u64 seq_loss,
 122                                                      const u8 win_loss)
 123 {
 124         struct dccp_li_hist_entry *tail = NULL, *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                         return NULL;
 132                 }
 133                 if (tail == NULL)
 134                         tail = entry;
 135                 list_add(&entry->dccplih_node, list);
 136         }
 137
 138         entry->dccplih_seqno     = seq_loss;
 139         entry->dccplih_win_count = win_loss;
 140         return tail;
 141 }
 142
 143 EXPORT_SYMBOL_GPL(dccp_li_hist_interval_new);