net/atm/atm_misc.c

   1 /* net/atm/atm_misc.c - Various functions for use by ATM drivers */
   2
   3 /* Written 1995-1999 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 <asm/atomic.h>
  11 #include <asm/errno.h>
  12
  13 #include "tunable.h"
  14
  15
  16 int atm_charge(struct atm_vcc *vcc,int truesize)
  17 {
  18         atm_force_charge(vcc,truesize);
  19         if (atomic_read(&vcc->rx_inuse) <= vcc->rx_quota) return 1;
  20         atm_return(vcc,truesize);
  21         vcc->stats->rx_drop++;
  22         return 0;
  23 }
  24
  25
  26 struct sk_buff *atm_alloc_charge(struct atm_vcc *vcc,int pdu_size,
  27     int gfp_flags)
  28 {
  29         int guess = atm_guess_pdu2truesize(pdu_size);
  30
  31         atm_force_charge(vcc,guess);
  32         if (atomic_read(&vcc->rx_inuse) <= vcc->rx_quota) {
  33                 struct sk_buff *skb = alloc_skb(pdu_size,gfp_flags);
  34
  35                 if (skb) {
  36                         atomic_add(skb->truesize-guess,&vcc->rx_inuse);
  37                         return skb;
  38                 }
  39         }
  40         atm_return(vcc,guess);
  41         vcc->stats->rx_drop++;
  42         return NULL;
  43 }
  44
  45
  46 static int check_ci(struct atm_vcc *vcc,short vpi,int vci)
  47 {
  48         struct atm_vcc *walk;
  49
  50         for (walk = vcc->dev->vccs; walk; walk = walk->next)
  51                 if ((walk->flags & ATM_VF_ADDR) && walk->vpi == vpi &&
  52                     walk->vci == vci && ((walk->qos.txtp.traffic_class !=
  53                     ATM_NONE && vcc->qos.txtp.traffic_class != ATM_NONE) ||
  54                     (walk->qos.rxtp.traffic_class != ATM_NONE &&
  55                     vcc->qos.rxtp.traffic_class != ATM_NONE)))
  56                         return -EADDRINUSE;
  57                 /* allow VCCs with same VPI/VCI iff they don't collide on
  58                    TX/RX (but we may refuse such sharing for other reasons,
  59                    e.g. if protocol requires to have both channels) */
  60         return 0;
  61 }
  62
  63
  64 int atm_find_ci(struct atm_vcc *vcc,short *vpi,int *vci)
  65 {
  66         static short p = 0; /* poor man's per-device cache */
  67         static int c = 0;
  68         short old_p;
  69         int old_c;
  70
  71         if (*vpi != ATM_VPI_ANY && *vci != ATM_VCI_ANY)
  72                 return check_ci(vcc,*vpi,*vci);
  73         /* last scan may have left values out of bounds for current device */
  74         if (*vpi != ATM_VPI_ANY) p = *vpi;
  75         else if (p >= 1 << vcc->dev->ci_range.vpi_bits) p = 0;
  76         if (*vci != ATM_VCI_ANY) c = *vci;
  77         else if (c < ATM_NOT_RSV_VCI || c >= 1 << vcc->dev->ci_range.vci_bits)
  78                         c = ATM_NOT_RSV_VCI;
  79         old_p = p;
  80         old_c = c;
  81         do {
  82                 if (!check_ci(vcc,p,c)) {
  83                         *vpi = p;
  84                         *vci = c;
  85                         return 0;
  86                 }
  87                 if (*vci == ATM_VCI_ANY) {
  88                         c++;
  89                         if (c >= 1 << vcc->dev->ci_range.vci_bits)
  90                                 c = ATM_NOT_RSV_VCI;
  91                 }
  92                 if ((c == ATM_NOT_RSV_VCI || *vci != ATM_VCI_ANY) &&
  93                     *vpi == ATM_VPI_ANY) {
  94                         p++;
  95                         if (p >= 1 << vcc->dev->ci_range.vpi_bits) p = 0;
  96                 }
  97         }
  98         while (old_p != p || old_c != c);
  99         return -EADDRINUSE;
 100 }
 101
 102
 103 /*
 104  * atm_pcr_goal returns the positive PCR if it should be rounded up, the
 105  * negative PCR if it should be rounded down, and zero if the maximum available
 106  * bandwidth should be used.
 107  *
 108  * The rules are as follows (* = maximum, - = absent (0), x = value "x",
 109  * (x+ = x or next value above x, x- = x or next value below):
 110  *
 111  *      min max pcr     result          min max pcr     result
 112  *      -   -   -       * (UBR only)    x   -   -       x+
 113  *      -   -   *       *               x   -   *       *
 114  *      -   -   z       z-              x   -   z       z-
 115  *      -   *   -       *               x   *   -       x+
 116  *      -   *   *       *               x   *   *       *
 117  *      -   *   z       z-              x   *   z       z-
 118  *      -   y   -       y-              x   y   -       x+
 119  *      -   y   *       y-              x   y   *       y-
 120  *      -   y   z       z-              x   y   z       z-
 121  *
 122  * All non-error cases can be converted with the following simple set of rules:
 123  *
 124  *   if pcr == z then z-
 125  *   else if min == x && pcr == - then x+
 126  *     else if max == y then y-
 127  *       else *
 128  */
 129
 130
 131 int atm_pcr_goal(struct atm_trafprm *tp)
 132 {
 133         if (tp->pcr && tp->pcr != ATM_MAX_PCR) return -tp->pcr;
 134         if (tp->min_pcr && !tp->pcr) return tp->min_pcr;
 135         if (tp->max_pcr != ATM_MAX_PCR) return -tp->max_pcr;
 136         return 0;
 137 }
 138
 139
 140 EXPORT_SYMBOL(atm_charge);
 141 EXPORT_SYMBOL(atm_alloc_charge);
 142 EXPORT_SYMBOL(atm_find_ci);
 143 EXPORT_SYMBOL(atm_pcr_goal);