linux/net/9p/util.c
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   1/*
   2 *  net/9p/util.c
   3 *
   4 *  This file contains some helper functions
   5 *
   6 *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
   7 *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
   8 *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
   9 *
  10 *  This program is free software; you can redistribute it and/or modify
  11 *  it under the terms of the GNU General Public License version 2
  12 *  as published by the Free Software Foundation.
  13 *
  14 *  This program is distributed in the hope that it will be useful,
  15 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 *  GNU General Public License for more details.
  18 *
  19 *  You should have received a copy of the GNU General Public License
  20 *  along with this program; if not, write to:
  21 *  Free Software Foundation
  22 *  51 Franklin Street, Fifth Floor
  23 *  Boston, MA  02111-1301  USA
  24 *
  25 */
  26
  27#include <linux/module.h>
  28#include <linux/errno.h>
  29#include <linux/fs.h>
  30#include <linux/sched.h>
  31#include <linux/parser.h>
  32#include <linux/idr.h>
  33#include <linux/slab.h>
  34#include <net/9p/9p.h>
  35
  36/**
  37 * struct p9_idpool - per-connection accounting for tag idpool
  38 * @lock: protects the pool
  39 * @pool: idr to allocate tag id from
  40 *
  41 */
  42
  43struct p9_idpool {
  44        spinlock_t lock;
  45        struct idr pool;
  46};
  47
  48/**
  49 * p9_idpool_create - create a new per-connection id pool
  50 *
  51 */
  52
  53struct p9_idpool *p9_idpool_create(void)
  54{
  55        struct p9_idpool *p;
  56
  57        p = kmalloc(sizeof(struct p9_idpool), GFP_KERNEL);
  58        if (!p)
  59                return ERR_PTR(-ENOMEM);
  60
  61        spin_lock_init(&p->lock);
  62        idr_init(&p->pool);
  63
  64        return p;
  65}
  66EXPORT_SYMBOL(p9_idpool_create);
  67
  68/**
  69 * p9_idpool_destroy - create a new per-connection id pool
  70 * @p: idpool to destroy
  71 */
  72
  73void p9_idpool_destroy(struct p9_idpool *p)
  74{
  75        idr_destroy(&p->pool);
  76        kfree(p);
  77}
  78EXPORT_SYMBOL(p9_idpool_destroy);
  79
  80/**
  81 * p9_idpool_get - allocate numeric id from pool
  82 * @p: pool to allocate from
  83 *
  84 * Bugs: This seems to be an awful generic function, should it be in idr.c with
  85 *            the lock included in struct idr?
  86 */
  87
  88int p9_idpool_get(struct p9_idpool *p)
  89{
  90        int i = 0;
  91        int error;
  92        unsigned long flags;
  93
  94retry:
  95        if (idr_pre_get(&p->pool, GFP_NOFS) == 0)
  96                return -1;
  97
  98        spin_lock_irqsave(&p->lock, flags);
  99
 100        /* no need to store exactly p, we just need something non-null */
 101        error = idr_get_new(&p->pool, p, &i);
 102        spin_unlock_irqrestore(&p->lock, flags);
 103
 104        if (error == -EAGAIN)
 105                goto retry;
 106        else if (error)
 107                return -1;
 108
 109        p9_debug(P9_DEBUG_MUX, " id %d pool %p\n", i, p);
 110        return i;
 111}
 112EXPORT_SYMBOL(p9_idpool_get);
 113
 114/**
 115 * p9_idpool_put - release numeric id from pool
 116 * @id: numeric id which is being released
 117 * @p: pool to release id into
 118 *
 119 * Bugs: This seems to be an awful generic function, should it be in idr.c with
 120 *            the lock included in struct idr?
 121 */
 122
 123void p9_idpool_put(int id, struct p9_idpool *p)
 124{
 125        unsigned long flags;
 126
 127        p9_debug(P9_DEBUG_MUX, " id %d pool %p\n", id, p);
 128
 129        spin_lock_irqsave(&p->lock, flags);
 130        idr_remove(&p->pool, id);
 131        spin_unlock_irqrestore(&p->lock, flags);
 132}
 133EXPORT_SYMBOL(p9_idpool_put);
 134
 135/**
 136 * p9_idpool_check - check if the specified id is available
 137 * @id: id to check
 138 * @p: pool to check
 139 */
 140
 141int p9_idpool_check(int id, struct p9_idpool *p)
 142{
 143        return idr_find(&p->pool, id) != NULL;
 144}
 145EXPORT_SYMBOL(p9_idpool_check);
 146
 147
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