net/atm/atm_misc.c

   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
  14 int 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 }
  23 EXPORT_SYMBOL(atm_charge);
  24
  25 struct 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 }
  45 EXPORT_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
  75 int 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 }
  85 EXPORT_SYMBOL(atm_pcr_goal);
  86
  87 void 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 }
  93 EXPORT_SYMBOL(sonet_copy_stats);
  94
  95 void 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 }
 101 EXPORT_SYMBOL(sonet_subtract_stats);