atm_misc.c

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/* net/atm/atm_misc.c - Various functions for use by ATM drivers */

/* Written 1995-2000 by Werner Almesberger, EPFL ICA */

#include <linux/module.h>
#include <linux/atm.h>
#include <linux/atmdev.h>
#include <linux/skbuff.h>
#include <linux/sonet.h>
#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/atomic.h>

int atm_charge(struct atm_vcc *vcc, int truesize)
{
    atm_force_charge(vcc, truesize);
    if (atomic_read(&sk_atm(vcc)->sk_rmem_alloc) <= sk_atm(vcc)->sk_rcvbuf)
        return 1;
    atm_return(vcc, truesize);
    atomic_inc(&vcc->stats->rx_drop);
    return 0;
}
EXPORT_SYMBOL(atm_charge);

struct sk_buff *atm_alloc_charge(struct atm_vcc *vcc, int pdu_size,
                 gfp_t gfp_flags)
{
    struct sock *sk = sk_atm(vcc);
    int guess = SKB_TRUESIZE(pdu_size);

    atm_force_charge(vcc, guess);
    if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf) {
        struct sk_buff *skb = alloc_skb(pdu_size, gfp_flags);

        if (skb) {
            atomic_add(skb->truesize-guess,
                   &sk->sk_rmem_alloc);
            return skb;
        }
    }
    atm_return(vcc, guess);
    atomic_inc(&vcc->stats->rx_drop);
    return NULL;
}
EXPORT_SYMBOL(atm_alloc_charge);


/*
 * atm_pcr_goal returns the positive PCR if it should be rounded up, the
 * negative PCR if it should be rounded down, and zero if the maximum available
 * bandwidth should be used.
 *
 * The rules are as follows (* = maximum, - = absent (0), x = value "x",
 * (x+ = x or next value above x, x- = x or next value below):
 *
 *  min max pcr result      min max pcr result
 *  -   -   -   * (UBR only)    x   -   -   x+
 *  -   -   *   *       x   -   *   *
 *  -   -   z   z-      x   -   z   z-
 *  -   *   -   *       x   *   -   x+
 *  -   *   *   *       x   *   *   *
 *  -   *   z   z-      x   *   z   z-
 *  -   y   -   y-      x   y   -   x+
 *  -   y   *   y-      x   y   *   y-
 *  -   y   z   z-      x   y   z   z-
 *
 * All non-error cases can be converted with the following simple set of rules:
 *
 *   if pcr == z then z-
 *   else if min == x && pcr == - then x+
 *     else if max == y then y-
 *   else *
 */

int atm_pcr_goal(const struct atm_trafprm *tp)
{
    if (tp->pcr && tp->pcr != ATM_MAX_PCR)
        return -tp->pcr;
    if (tp->min_pcr && !tp->pcr)
        return tp->min_pcr;
    if (tp->max_pcr != ATM_MAX_PCR)
        return -tp->max_pcr;
    return 0;
}
EXPORT_SYMBOL(atm_pcr_goal);

void sonet_copy_stats(struct k_sonet_stats *from, struct sonet_stats *to)
{
#define __HANDLE_ITEM(i) to->i = atomic_read(&from->i)
    __SONET_ITEMS
#undef __HANDLE_ITEM
}
EXPORT_SYMBOL(sonet_copy_stats);

void sonet_subtract_stats(struct k_sonet_stats *from, struct sonet_stats *to)
{
#define __HANDLE_ITEM(i) atomic_sub(to->i, &from->i)
    __SONET_ITEMS
#undef __HANDLE_ITEM
}
EXPORT_SYMBOL(sonet_subtract_stats);