xref: /kernel/linux/linux-5.10/net/atm/atm_misc.c (revision 8c2ecf20) 
1// SPDX-License-Identifier: GPL-2.0
2/* net/atm/atm_misc.c - Various functions for use by ATM drivers */
3
4/* Written 1995-2000 by Werner Almesberger, EPFL ICA */
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 <linux/errno.h>
13#include <linux/atomic.h>
14
15int atm_charge(struct atm_vcc *vcc, int truesize)
16{
17	atm_force_charge(vcc, truesize);
18	if (atomic_read(&sk_atm(vcc)->sk_rmem_alloc) <= sk_atm(vcc)->sk_rcvbuf)
19		return 1;
20	atm_return(vcc, truesize);
21	atomic_inc(&vcc->stats->rx_drop);
22	return 0;
23}
24EXPORT_SYMBOL(atm_charge);
25
26struct sk_buff *atm_alloc_charge(struct atm_vcc *vcc, int pdu_size,
27				 gfp_t gfp_flags)
28{
29	struct sock *sk = sk_atm(vcc);
30	int guess = SKB_TRUESIZE(pdu_size);
31
32	atm_force_charge(vcc, guess);
33	if (atomic_read(&sk->sk_rmem_alloc) <= 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				   &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}
46EXPORT_SYMBOL(atm_alloc_charge);
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
76int atm_pcr_goal(const struct atm_trafprm *tp)
77{
78	if (tp->pcr && tp->pcr != ATM_MAX_PCR)
79		return -tp->pcr;
80	if (tp->min_pcr && !tp->pcr)
81		return tp->min_pcr;
82	if (tp->max_pcr != ATM_MAX_PCR)
83		return -tp->max_pcr;
84	return 0;
85}
86EXPORT_SYMBOL(atm_pcr_goal);
87
88void sonet_copy_stats(struct k_sonet_stats *from, struct sonet_stats *to)
89{
90#define __HANDLE_ITEM(i) to->i = atomic_read(&from->i)
91	__SONET_ITEMS
92#undef __HANDLE_ITEM
93}
94EXPORT_SYMBOL(sonet_copy_stats);
95
96void sonet_subtract_stats(struct k_sonet_stats *from, struct sonet_stats *to)
97{
98#define __HANDLE_ITEM(i) atomic_sub(to->i, &from->i)
99	__SONET_ITEMS
100#undef __HANDLE_ITEM
101}
102EXPORT_SYMBOL(sonet_subtract_stats);
103