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