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) 57 alloc->last += get_random_u32_below(RANDOM_SKIP); 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; 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 alloc->start = start; 86 alloc->flags = flags; 87 if (flags & C4IW_ID_TABLE_F_RANDOM) 88 alloc->last = get_random_u32_below(RANDOM_SKIP); 89 else 90 alloc->last = 0; 91 alloc->max = num; 92 spin_lock_init(&alloc->lock); 93 alloc->table = bitmap_zalloc(num, GFP_KERNEL); 94 if (!alloc->table) 95 return -ENOMEM; 96 97 if (!(alloc->flags & C4IW_ID_TABLE_F_EMPTY)) 98 bitmap_set(alloc->table, 0, reserved); 99 100 return 0; 101 } 102 103 void c4iw_id_table_free(struct c4iw_id_table *alloc) 104 { 105 bitmap_free(alloc->table); 106 } 107