1/*
2 * Copyright (c) 2011-2013 Chelsio Communications.  All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses.  You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 *     Redistribution and use in source and binary forms, with or
11 *     without modification, are permitted provided that the following
12 *     conditions are met:
13 *
14 *      - Redistributions of source code must retain the above
15 *        copyright notice, this list of conditions and the following
16 *        disclaimer.
17 *
18 *      - Redistributions in binary form must reproduce the above
19 *        copyright notice, this list of conditions and the following
20 *        disclaimer in the documentation and/or other materials
21 *        provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 */
32#include <sys/cdefs.h>
33__FBSDID("$FreeBSD$");
34
35#include "opt_inet.h"
36
37#ifdef TCP_OFFLOAD
38#include <sys/libkern.h>
39#include "iw_cxgbe.h"
40
41#define RANDOM_SKIP 16
42
43/*
44 * Trivial bitmap-based allocator. If the random flag is set, the
45 * allocator is designed to:
46 * - pseudo-randomize the id returned such that it is not trivially predictable.
47 * - avoid reuse of recently used id (at the expense of predictability)
48 */
49u32 c4iw_id_alloc(struct c4iw_id_table *alloc)
50{
51	unsigned long flags;
52	u32 obj;
53
54	spin_lock_irqsave(&alloc->lock, flags);
55
56	obj = find_next_zero_bit(alloc->table, alloc->max, alloc->last);
57	if (obj >= alloc->max)
58		obj = find_first_zero_bit(alloc->table, alloc->max);
59
60	if (obj < alloc->max) {
61		if (alloc->flags & C4IW_ID_TABLE_F_RANDOM)
62			alloc->last += arc4random() % RANDOM_SKIP;
63		else
64			alloc->last = obj + 1;
65		if (alloc->last >= alloc->max)
66			alloc->last = 0;
67		set_bit(obj, alloc->table);
68		obj += alloc->start;
69	} else
70		obj = -1;
71
72	spin_unlock_irqrestore(&alloc->lock, flags);
73	return obj;
74}
75
76void c4iw_id_free(struct c4iw_id_table *alloc, u32 obj)
77{
78	unsigned long flags;
79
80	obj -= alloc->start;
81	BUG_ON((int)obj < 0);
82
83	spin_lock_irqsave(&alloc->lock, flags);
84	clear_bit(obj, alloc->table);
85	spin_unlock_irqrestore(&alloc->lock, flags);
86}
87
88int c4iw_id_table_alloc(struct c4iw_id_table *alloc, u32 start, u32 num,
89			u32 reserved, u32 flags)
90{
91	int i;
92
93	alloc->start = start;
94	alloc->flags = flags;
95	if (flags & C4IW_ID_TABLE_F_RANDOM)
96		alloc->last = arc4random() % RANDOM_SKIP;
97	else
98		alloc->last = 0;
99	alloc->max  = num;
100	spin_lock_init(&alloc->lock);
101	alloc->table = kmalloc(BITS_TO_LONGS(num) * sizeof(long),
102				GFP_KERNEL);
103	if (!alloc->table)
104		return -ENOMEM;
105
106	bitmap_zero(alloc->table, num);
107	if (!(alloc->flags & C4IW_ID_TABLE_F_EMPTY))
108		for (i = 0; i < reserved; ++i)
109			set_bit(i, alloc->table);
110
111	return 0;
112}
113
114void c4iw_id_table_free(struct c4iw_id_table *alloc)
115{
116	kfree(alloc->table);
117}
118#endif
119