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