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
   6 #include <linux/module.h>
   7 #include <linux/atm.h>
   8 #include <linux/atmdev.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/sonet.h>
  11 #include <linux/bitops.h>
  12 #include <asm/atomic.h>
  13 #include <asm/errno.h>
  14
  15
  16 int atm_charge(struct atm_vcc *vcc,int truesize)
  17 {
  18         atm_force_charge(vcc,truesize);
  19         if (atomic_read(&sk_atm(vcc)->sk_rmem_alloc) <= sk_atm(vcc)->sk_rcvbuf)
  20                 return 1;
  21         atm_return(vcc,truesize);
  22         atomic_inc(&vcc->stats->rx_drop);
  23         return 0;
  24 }
  25
  26
  27 struct sk_buff *atm_alloc_charge(struct atm_vcc *vcc,int pdu_size,
  28     int gfp_flags)
  29 {
  30         struct sock *sk = sk_atm(vcc);
  31         int guess = atm_guess_pdu2truesize(pdu_size);
  32
  33         atm_force_charge(vcc,guess);
  34         if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf) {
  35                 struct sk_buff *skb = alloc_skb(pdu_size,gfp_flags);
  36
  37                 if (skb) {
  38                         atomic_add(skb->truesize-guess,
  39                                    &sk->sk_rmem_alloc);
  40                         return skb;
  41                 }
  42         }
  43         atm_return(vcc,guess);
  44         atomic_inc(&vcc->stats->rx_drop);
  45         return NULL;
  46 }
  47
  48
  49 /*
  50  * atm_pcr_goal returns the positive PCR if it should be rounded up, the
  51  * negative PCR if it should be rounded down, and zero if the maximum available
  52  * bandwidth should be used.
  53  *
  54  * The rules are as follows (* = maximum, - = absent (0), x = value "x",
  55  * (x+ = x or next value above x, x- = x or next value below):
  56  *
  57  *      min max pcr     result          min max pcr     result
  58  *      -   -   -       * (UBR only)    x   -   -       x+
  59  *      -   -   *       *               x   -   *       *
  60  *      -   -   z       z-              x   -   z       z-
  61  *      -   *   -       *               x   *   -       x+
  62  *      -   *   *       *               x   *   *       *
  63  *      -   *   z       z-              x   *   z       z-
  64  *      -   y   -       y-              x   y   -       x+
  65  *      -   y   *       y-              x   y   *       y-
  66  *      -   y   z       z-              x   y   z       z-
  67  *
  68  * All non-error cases can be converted with the following simple set of rules:
  69  *
  70  *   if pcr == z then z-
  71  *   else if min == x && pcr == - then x+
  72  *     else if max == y then y-
  73  *       else *
  74  */
  75
  76
  77 int atm_pcr_goal(struct atm_trafprm *tp)
  78 {
  79         if (tp->pcr && tp->pcr != ATM_MAX_PCR) return -tp->pcr;
  80         if (tp->min_pcr && !tp->pcr) return tp->min_pcr;
  81         if (tp->max_pcr != ATM_MAX_PCR) return -tp->max_pcr;
  82         return 0;
  83 }
  84
  85
  86 void sonet_copy_stats(struct k_sonet_stats *from,struct sonet_stats *to)
  87 {
  88 #define __HANDLE_ITEM(i) to->i = atomic_read(&from->i)
  89         __SONET_ITEMS
  90 #undef __HANDLE_ITEM
  91 }
  92
  93
  94 void sonet_subtract_stats(struct k_sonet_stats *from,struct sonet_stats *to)
  95 {
  96 #define __HANDLE_ITEM(i) atomic_sub(to->i,&from->i)
  97         __SONET_ITEMS
  98 #undef __HANDLE_ITEM
  99 }
 100
 101
 102 EXPORT_SYMBOL(atm_charge);
 103 EXPORT_SYMBOL(atm_alloc_charge);
 104 EXPORT_SYMBOL(atm_pcr_goal);
 105 EXPORT_SYMBOL(sonet_copy_stats);
 106 EXPORT_SYMBOL(sonet_subtract_stats);