1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2011-2013 Chelsio Communications. All rights reserved. 5 * 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: 11 * 12 * Redistribution and use in source and binary forms, with or 13 * without modification, are permitted provided that the following 14 * conditions are met: 15 * 16 * - Redistributions of source code must retain the above 17 * copyright notice, this list of conditions and the following 18 * disclaimer. 19 * 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. 24 * 25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 26 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 27 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 28 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 29 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 30 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 31 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 32 * SOFTWARE. 33 */ 34 #include <sys/cdefs.h> 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 */ 49 u32 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 76 void 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 88 int 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 } 113 114 void c4iw_id_table_free(struct c4iw_id_table *alloc) 115 { 116 kfree(alloc->table); 117 } 118 #endif 119