2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2011-2013 Chelsio Communications. All rights reserved.
6 * This software is available to you under a choice of one of two
7 * licenses. You may choose to be licensed under the terms of the GNU
8 * General Public License (GPL) Version 2, available from the file
9 * COPYING in the main directory of this source tree, or the
10 * OpenIB.org BSD license below:
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
16 * - Redistributions of source code must retain the above
17 * copyright notice, this list of conditions and the following
20 * - Redistributions in binary form must reproduce the above
21 * copyright notice, this list of conditions and the following
22 * disclaimer in the documentation and/or other materials
23 * provided with the distribution.
25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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31 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
40 #include <sys/libkern.h>
43 #define RANDOM_SKIP 16
46 * Trivial bitmap-based allocator. If the random flag is set, the
47 * allocator is designed to:
48 * - pseudo-randomize the id returned such that it is not trivially predictable.
49 * - avoid reuse of recently used id (at the expense of predictability)
51 u32 c4iw_id_alloc(struct c4iw_id_table *alloc)
56 spin_lock_irqsave(&alloc->lock, flags);
58 obj = find_next_zero_bit(alloc->table, alloc->max, alloc->last);
59 if (obj >= alloc->max)
60 obj = find_first_zero_bit(alloc->table, alloc->max);
62 if (obj < alloc->max) {
63 if (alloc->flags & C4IW_ID_TABLE_F_RANDOM)
64 alloc->last += arc4random() % RANDOM_SKIP;
66 alloc->last = obj + 1;
67 if (alloc->last >= alloc->max)
69 set_bit(obj, alloc->table);
74 spin_unlock_irqrestore(&alloc->lock, flags);
78 void c4iw_id_free(struct c4iw_id_table *alloc, u32 obj)
85 spin_lock_irqsave(&alloc->lock, flags);
86 clear_bit(obj, alloc->table);
87 spin_unlock_irqrestore(&alloc->lock, flags);
90 int c4iw_id_table_alloc(struct c4iw_id_table *alloc, u32 start, u32 num,
91 u32 reserved, u32 flags)
97 if (flags & C4IW_ID_TABLE_F_RANDOM)
98 alloc->last = arc4random() % RANDOM_SKIP;
102 spin_lock_init(&alloc->lock);
103 alloc->table = kmalloc(BITS_TO_LONGS(num) * sizeof(long),
108 bitmap_zero(alloc->table, num);
109 if (!(alloc->flags & C4IW_ID_TABLE_F_EMPTY))
110 for (i = 0; i < reserved; ++i)
111 set_bit(i, alloc->table);
116 void c4iw_id_table_free(struct c4iw_id_table *alloc)