112 lines
3.2 KiB
C
112 lines
3.2 KiB
C
/*
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* Copyright (c) 2011 Chelsio Communications. All rights reserved.
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*
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* This software is available to you under a choice of one of two
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* licenses. You may choose to be licensed under the terms of the GNU
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* General Public License (GPL) Version 2, available from the file
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* COPYING in the main directory of this source tree, or the
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* OpenIB.org BSD license below:
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*
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* Redistribution and use in source and binary forms, with or
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* without modification, are permitted provided that the following
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* conditions are met:
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*
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* - Redistributions of source code must retain the above
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* copyright notice, this list of conditions and the following
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* disclaimer.
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*
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* - Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials
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* provided with the distribution.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include <linux/kernel.h>
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#include <linux/random.h>
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#include "iw_cxgb4.h"
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#define RANDOM_SKIP 16
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/*
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* Trivial bitmap-based allocator. If the random flag is set, the
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* allocator is designed to:
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* - pseudo-randomize the id returned such that it is not trivially predictable.
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* - avoid reuse of recently used id (at the expense of predictability)
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*/
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u32 c4iw_id_alloc(struct c4iw_id_table *alloc)
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{
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unsigned long flags;
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u32 obj;
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spin_lock_irqsave(&alloc->lock, flags);
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obj = find_next_zero_bit(alloc->table, alloc->max, alloc->last);
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if (obj >= alloc->max)
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obj = find_first_zero_bit(alloc->table, alloc->max);
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if (obj < alloc->max) {
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if (alloc->flags & C4IW_ID_TABLE_F_RANDOM)
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alloc->last += prandom_u32() % RANDOM_SKIP;
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else
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alloc->last = obj + 1;
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if (alloc->last >= alloc->max)
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alloc->last = 0;
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set_bit(obj, alloc->table);
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obj += alloc->start;
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} else
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obj = -1;
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spin_unlock_irqrestore(&alloc->lock, flags);
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return obj;
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}
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void c4iw_id_free(struct c4iw_id_table *alloc, u32 obj)
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{
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unsigned long flags;
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obj -= alloc->start;
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spin_lock_irqsave(&alloc->lock, flags);
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clear_bit(obj, alloc->table);
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spin_unlock_irqrestore(&alloc->lock, flags);
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}
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int c4iw_id_table_alloc(struct c4iw_id_table *alloc, u32 start, u32 num,
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u32 reserved, u32 flags)
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{
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int i;
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alloc->start = start;
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alloc->flags = flags;
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if (flags & C4IW_ID_TABLE_F_RANDOM)
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alloc->last = prandom_u32() % RANDOM_SKIP;
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else
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alloc->last = 0;
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alloc->max = num;
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spin_lock_init(&alloc->lock);
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alloc->table = kmalloc(BITS_TO_LONGS(num) * sizeof(long),
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GFP_KERNEL);
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if (!alloc->table)
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return -ENOMEM;
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bitmap_zero(alloc->table, num);
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if (!(alloc->flags & C4IW_ID_TABLE_F_EMPTY))
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for (i = 0; i < reserved; ++i)
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set_bit(i, alloc->table);
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return 0;
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}
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void c4iw_id_table_free(struct c4iw_id_table *alloc)
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{
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kfree(alloc->table);
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}
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