LXR linux/net/9p/util.c

   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 <net/9p/9p.h>
  34
  35/**
  36 * struct p9_idpool - per-connection accounting for tag idpool
  37 * @lock: protects the pool
  38 * @pool: idr to allocate tag id from
  39 *
  40 */
  41
  42struct p9_idpool {
  43        spinlock_t lock;
  44        struct idr pool;
  45};
  46
  47/**
  48 * p9_idpool_create - create a new per-connection id pool
  49 *
  50 */
  51
  52struct p9_idpool *p9_idpool_create(void)
  53{
  54        struct p9_idpool *p;
  55
  56        p = kmalloc(sizeof(struct p9_idpool), GFP_KERNEL);
  57        if (!p)
  58                return ERR_PTR(-ENOMEM);
  59
  60        spin_lock_init(&p->lock);
  61        idr_init(&p->pool);
  62
  63        return p;
  64}
  65EXPORT_SYMBOL(p9_idpool_create);
  66
  67/**
  68 * p9_idpool_destroy - create a new per-connection id pool
  69 * @p: idpool to destory
  70 */
  71
  72void p9_idpool_destroy(struct p9_idpool *p)
  73{
  74        idr_destroy(&p->pool);
  75        kfree(p);
  76}
  77EXPORT_SYMBOL(p9_idpool_destroy);
  78
  79/**
  80 * p9_idpool_get - allocate numeric id from pool
  81 * @p: pool to allocate from
  82 *
  83 * Bugs: This seems to be an awful generic function, should it be in idr.c with
  84 *            the lock included in struct idr?
  85 */
  86
  87int p9_idpool_get(struct p9_idpool *p)
  88{
  89        int i = 0;
  90        int error;
  91        unsigned long flags;
  92
  93retry:
  94        if (idr_pre_get(&p->pool, GFP_KERNEL) == 0)
  95                return 0;
  96
  97        spin_lock_irqsave(&p->lock, flags);
  98
  99        /* no need to store exactly p, we just need something non-null */
 100        error = idr_get_new(&p->pool, p, &i);
 101        spin_unlock_irqrestore(&p->lock, flags);
 102
 103        if (error == -EAGAIN)
 104                goto retry;
 105        else if (error)
 106                return -1;
 107
 108        P9_DPRINTK(P9_DEBUG_MUX, " id %d pool %p\n", i, p);
 109        return i;
 110}
 111EXPORT_SYMBOL(p9_idpool_get);
 112
 113/**
 114 * p9_idpool_put - release numeric id from pool
 115 * @id: numeric id which is being released
 116 * @p: pool to release id into
 117 *
 118 * Bugs: This seems to be an awful generic function, should it be in idr.c with
 119 *            the lock included in struct idr?
 120 */
 121
 122void p9_idpool_put(int id, struct p9_idpool *p)
 123{
 124        unsigned long flags;
 125
 126        P9_DPRINTK(P9_DEBUG_MUX, " id %d pool %p\n", id, p);
 127
 128        spin_lock_irqsave(&p->lock, flags);
 129        idr_remove(&p->pool, id);
 130        spin_unlock_irqrestore(&p->lock, flags);
 131}
 132EXPORT_SYMBOL(p9_idpool_put);
 133
 134/**
 135 * p9_idpool_check - check if the specified id is available
 136 * @id: id to check
 137 * @p: pool to check
 138 */
 139
 140int p9_idpool_check(int id, struct p9_idpool *p)
 141{
 142        return idr_find(&p->pool, id) != NULL;
 143}
 144EXPORT_SYMBOL(p9_idpool_check);
 145
 146