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1 | /* |
2 | * Copyright (c) 2011 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 <linux/kernel.h> | |
33 | #include <linux/random.h> | |
34 | #include "iw_cxgb4.h" | |
35 | ||
36 | #define RANDOM_SKIP 16 | |
37 | ||
38 | /* | |
39 | * Trivial bitmap-based allocator. If the random flag is set, the | |
40 | * allocator is designed to: | |
41 | * - pseudo-randomize the id returned such that it is not trivially predictable. | |
42 | * - avoid reuse of recently used id (at the expense of predictability) | |
43 | */ | |
44 | u32 c4iw_id_alloc(struct c4iw_id_table *alloc) | |
45 | { | |
46 | unsigned long flags; | |
47 | u32 obj; | |
48 | ||
49 | spin_lock_irqsave(&alloc->lock, flags); | |
50 | ||
51 | obj = find_next_zero_bit(alloc->table, alloc->max, alloc->last); | |
52 | if (obj >= alloc->max) | |
53 | obj = find_first_zero_bit(alloc->table, alloc->max); | |
54 | ||
55 | if (obj < alloc->max) { | |
56 | if (alloc->flags & C4IW_ID_TABLE_F_RANDOM) | |
50bea5c0 | 57 | alloc->last += prandom_u32() % RANDOM_SKIP; |
ec3eead2 VP |
58 | else |
59 | alloc->last = obj + 1; | |
60 | if (alloc->last >= alloc->max) | |
61 | alloc->last = 0; | |
62 | set_bit(obj, alloc->table); | |
63 | obj += alloc->start; | |
64 | } else | |
65 | obj = -1; | |
66 | ||
67 | spin_unlock_irqrestore(&alloc->lock, flags); | |
68 | return obj; | |
69 | } | |
70 | ||
71 | void c4iw_id_free(struct c4iw_id_table *alloc, u32 obj) | |
72 | { | |
73 | unsigned long flags; | |
74 | ||
75 | obj -= alloc->start; | |
ec3eead2 VP |
76 | |
77 | spin_lock_irqsave(&alloc->lock, flags); | |
78 | clear_bit(obj, alloc->table); | |
79 | spin_unlock_irqrestore(&alloc->lock, flags); | |
80 | } | |
81 | ||
82 | int c4iw_id_table_alloc(struct c4iw_id_table *alloc, u32 start, u32 num, | |
83 | u32 reserved, u32 flags) | |
84 | { | |
85 | int i; | |
86 | ||
87 | alloc->start = start; | |
88 | alloc->flags = flags; | |
89 | if (flags & C4IW_ID_TABLE_F_RANDOM) | |
50bea5c0 | 90 | alloc->last = prandom_u32() % RANDOM_SKIP; |
ec3eead2 VP |
91 | else |
92 | alloc->last = 0; | |
93 | alloc->max = num; | |
94 | spin_lock_init(&alloc->lock); | |
95 | alloc->table = kmalloc(BITS_TO_LONGS(num) * sizeof(long), | |
96 | GFP_KERNEL); | |
97 | if (!alloc->table) | |
98 | return -ENOMEM; | |
99 | ||
100 | bitmap_zero(alloc->table, num); | |
101 | if (!(alloc->flags & C4IW_ID_TABLE_F_EMPTY)) | |
102 | for (i = 0; i < reserved; ++i) | |
103 | set_bit(i, alloc->table); | |
104 | ||
105 | return 0; | |
106 | } | |
107 | ||
108 | void c4iw_id_table_free(struct c4iw_id_table *alloc) | |
109 | { | |
110 | kfree(alloc->table); | |
111 | } |