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(&vcc->sk->sk_rmem_alloc) <= vcc->sk->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         int guess = atm_guess_pdu2truesize(pdu_size);
  31
  32         atm_force_charge(vcc,guess);
  33         if (atomic_read(&vcc->sk->sk_rmem_alloc) <= vcc->sk->sk_rcvbuf) {
  34                 struct sk_buff *skb = alloc_skb(pdu_size,gfp_flags);
  35
  36                 if (skb) {
  37                         atomic_add(skb->truesize-guess,
  38                                    &vcc->sk->sk_rmem_alloc);
  39                         return skb;
  40                 }
  41         }
  42         atm_return(vcc,guess);
  43         atomic_inc(&vcc->stats->rx_drop);
  44         return NULL;
  45 }
  46
  47
  48 static int check_ci(struct atm_vcc *vcc,short vpi,int vci)
  49 {
  50         struct hlist_node *node;
  51         struct sock *s;
  52         struct atm_vcc *walk;
  53
  54         sk_for_each(s, node, &vcc_sklist) {
  55                 walk = atm_sk(s);
  56                 if (walk->dev != vcc->dev)
  57                         continue;
  58                 if (test_bit(ATM_VF_ADDR,&walk->flags) && walk->vpi == vpi &&
  59                     walk->vci == vci && ((walk->qos.txtp.traffic_class !=
  60                     ATM_NONE && vcc->qos.txtp.traffic_class != ATM_NONE) ||
  61                     (walk->qos.rxtp.traffic_class != ATM_NONE &&
  62                     vcc->qos.rxtp.traffic_class != ATM_NONE)))
  63                         return -EADDRINUSE;
  64         }
  65                 /* allow VCCs with same VPI/VCI iff they don't collide on
  66                    TX/RX (but we may refuse such sharing for other reasons,
  67                    e.g. if protocol requires to have both channels) */
  68         return 0;
  69 }
  70
  71
  72 int atm_find_ci(struct atm_vcc *vcc,short *vpi,int *vci)
  73 {
  74         static short p = 0; /* poor man's per-device cache */
  75         static int c = 0;
  76         short old_p;
  77         int old_c;
  78         int err;
  79
  80         read_lock(&vcc_sklist_lock);
  81         if (*vpi != ATM_VPI_ANY && *vci != ATM_VCI_ANY) {
  82                 err = check_ci(vcc,*vpi,*vci);
  83                 read_unlock(&vcc_sklist_lock);
  84                 return err;
  85         }
  86         /* last scan may have left values out of bounds for current device */
  87         if (*vpi != ATM_VPI_ANY) p = *vpi;
  88         else if (p >= 1 << vcc->dev->ci_range.vpi_bits) p = 0;
  89         if (*vci != ATM_VCI_ANY) c = *vci;
  90         else if (c < ATM_NOT_RSV_VCI || c >= 1 << vcc->dev->ci_range.vci_bits)
  91                         c = ATM_NOT_RSV_VCI;
  92         old_p = p;
  93         old_c = c;
  94         do {
  95                 if (!check_ci(vcc,p,c)) {
  96                         *vpi = p;
  97                         *vci = c;
  98                         read_unlock(&vcc_sklist_lock);
  99                         return 0;
 100                 }
 101                 if (*vci == ATM_VCI_ANY) {
 102                         c++;
 103                         if (c >= 1 << vcc->dev->ci_range.vci_bits)
 104                                 c = ATM_NOT_RSV_VCI;
 105                 }
 106                 if ((c == ATM_NOT_RSV_VCI || *vci != ATM_VCI_ANY) &&
 107                     *vpi == ATM_VPI_ANY) {
 108                         p++;
 109                         if (p >= 1 << vcc->dev->ci_range.vpi_bits) p = 0;
 110                 }
 111         }
 112         while (old_p != p || old_c != c);
 113         read_unlock(&vcc_sklist_lock);
 114         return -EADDRINUSE;
 115 }
 116
 117
 118 /*
 119  * atm_pcr_goal returns the positive PCR if it should be rounded up, the
 120  * negative PCR if it should be rounded down, and zero if the maximum available
 121  * bandwidth should be used.
 122  *
 123  * The rules are as follows (* = maximum, - = absent (0), x = value "x",
 124  * (x+ = x or next value above x, x- = x or next value below):
 125  *
 126  *      min max pcr     result          min max pcr     result
 127  *      -   -   -       * (UBR only)    x   -   -       x+
 128  *      -   -   *       *               x   -   *       *
 129  *      -   -   z       z-              x   -   z       z-
 130  *      -   *   -       *               x   *   -       x+
 131  *      -   *   *       *               x   *   *       *
 132  *      -   *   z       z-              x   *   z       z-
 133  *      -   y   -       y-              x   y   -       x+
 134  *      -   y   *       y-              x   y   *       y-
 135  *      -   y   z       z-              x   y   z       z-
 136  *
 137  * All non-error cases can be converted with the following simple set of rules:
 138  *
 139  *   if pcr == z then z-
 140  *   else if min == x && pcr == - then x+
 141  *     else if max == y then y-
 142  *       else *
 143  */
 144
 145
 146 int atm_pcr_goal(struct atm_trafprm *tp)
 147 {
 148         if (tp->pcr && tp->pcr != ATM_MAX_PCR) return -tp->pcr;
 149         if (tp->min_pcr && !tp->pcr) return tp->min_pcr;
 150         if (tp->max_pcr != ATM_MAX_PCR) return -tp->max_pcr;
 151         return 0;
 152 }
 153
 154
 155 void sonet_copy_stats(struct k_sonet_stats *from,struct sonet_stats *to)
 156 {
 157 #define __HANDLE_ITEM(i) to->i = atomic_read(&from->i)
 158         __SONET_ITEMS
 159 #undef __HANDLE_ITEM
 160 }
 161
 162
 163 void sonet_subtract_stats(struct k_sonet_stats *from,struct sonet_stats *to)
 164 {
 165 #define __HANDLE_ITEM(i) atomic_sub(to->i,&from->i)
 166         __SONET_ITEMS
 167 #undef __HANDLE_ITEM
 168 }
 169
 170
 171 EXPORT_SYMBOL(atm_charge);
 172 EXPORT_SYMBOL(atm_alloc_charge);
 173 EXPORT_SYMBOL(atm_find_ci);
 174 EXPORT_SYMBOL(atm_pcr_goal);
 175 EXPORT_SYMBOL(sonet_copy_stats);
 176 EXPORT_SYMBOL(sonet_subtract_stats);