linux/net/atm/atm_misc.c
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   1/* net/atm/atm_misc.c - Various functions for use by ATM drivers */
   2
   3/* Written 1995-2000 by Werner Almesberger, EPFL ICA */
   4
   5#include <linux/module.h>
   6#include <linux/atm.h>
   7#include <linux/atmdev.h>
   8#include <linux/skbuff.h>
   9#include <linux/sonet.h>
  10#include <linux/bitops.h>
  11#include <linux/errno.h>
  12#include <linux/atomic.h>
  13
  14int atm_charge(struct atm_vcc *vcc, int truesize)
  15{
  16        atm_force_charge(vcc, truesize);
  17        if (atomic_read(&sk_atm(vcc)->sk_rmem_alloc) <= sk_atm(vcc)->sk_rcvbuf)
  18                return 1;
  19        atm_return(vcc, truesize);
  20        atomic_inc(&vcc->stats->rx_drop);
  21        return 0;
  22}
  23EXPORT_SYMBOL(atm_charge);
  24
  25struct sk_buff *atm_alloc_charge(struct atm_vcc *vcc, int pdu_size,
  26                                 gfp_t gfp_flags)
  27{
  28        struct sock *sk = sk_atm(vcc);
  29        int guess = SKB_TRUESIZE(pdu_size);
  30
  31        atm_force_charge(vcc, guess);
  32        if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf) {
  33                struct sk_buff *skb = alloc_skb(pdu_size, gfp_flags);
  34
  35                if (skb) {
  36                        atomic_add(skb->truesize-guess,
  37                                   &sk->sk_rmem_alloc);
  38                        return skb;
  39                }
  40        }
  41        atm_return(vcc, guess);
  42        atomic_inc(&vcc->stats->rx_drop);
  43        return NULL;
  44}
  45EXPORT_SYMBOL(atm_alloc_charge);
  46
  47
  48/*
  49 * atm_pcr_goal returns the positive PCR if it should be rounded up, the
  50 * negative PCR if it should be rounded down, and zero if the maximum available
  51 * bandwidth should be used.
  52 *
  53 * The rules are as follows (* = maximum, - = absent (0), x = value "x",
  54 * (x+ = x or next value above x, x- = x or next value below):
  55 *
  56 *      min max pcr     result          min max pcr     result
  57 *      -   -   -       * (UBR only)    x   -   -       x+
  58 *      -   -   *       *               x   -   *       *
  59 *      -   -   z       z-              x   -   z       z-
  60 *      -   *   -       *               x   *   -       x+
  61 *      -   *   *       *               x   *   *       *
  62 *      -   *   z       z-              x   *   z       z-
  63 *      -   y   -       y-              x   y   -       x+
  64 *      -   y   *       y-              x   y   *       y-
  65 *      -   y   z       z-              x   y   z       z-
  66 *
  67 * All non-error cases can be converted with the following simple set of rules:
  68 *
  69 *   if pcr == z then z-
  70 *   else if min == x && pcr == - then x+
  71 *     else if max == y then y-
  72 *       else *
  73 */
  74
  75int atm_pcr_goal(const struct atm_trafprm *tp)
  76{
  77        if (tp->pcr && tp->pcr != ATM_MAX_PCR)
  78                return -tp->pcr;
  79        if (tp->min_pcr && !tp->pcr)
  80                return tp->min_pcr;
  81        if (tp->max_pcr != ATM_MAX_PCR)
  82                return -tp->max_pcr;
  83        return 0;
  84}
  85EXPORT_SYMBOL(atm_pcr_goal);
  86
  87void sonet_copy_stats(struct k_sonet_stats *from, struct sonet_stats *to)
  88{
  89#define __HANDLE_ITEM(i) to->i = atomic_read(&from->i)
  90        __SONET_ITEMS
  91#undef __HANDLE_ITEM
  92}
  93EXPORT_SYMBOL(sonet_copy_stats);
  94
  95void sonet_subtract_stats(struct k_sonet_stats *from, struct sonet_stats *to)
  96{
  97#define __HANDLE_ITEM(i) atomic_sub(to->i, &from->i)
  98        __SONET_ITEMS
  99#undef __HANDLE_ITEM
 100}
 101EXPORT_SYMBOL(sonet_subtract_stats);
 102
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