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 <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
  43 struct 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
  53 struct 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 }
  66 EXPORT_SYMBOL(p9_idpool_create);
  67
  68 /**
  69  * p9_idpool_destroy - create a new per-connection id pool
  70  * @p: idpool to destroy
  71  */
  72
  73 void p9_idpool_destroy(struct p9_idpool *p)
  74 {
  75         idr_destroy(&p->pool);
  76         kfree(p);
  77 }
  78 EXPORT_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
  88 int p9_idpool_get(struct p9_idpool *p)
  89 {
  90         int i;
  91         unsigned long flags;
  92
  93         idr_preload(GFP_NOFS);
  94         spin_lock_irqsave(&p->lock, flags);
  95
  96         /* no need to store exactly p, we just need something non-null */
  97         i = idr_alloc(&p->pool, p, 0, 0, GFP_NOWAIT);
  98
  99         spin_unlock_irqrestore(&p->lock, flags);
 100         idr_preload_end();
 101         if (i < 0)
 102                 return -1;
 103
 104         p9_debug(P9_DEBUG_MUX, " id %d pool %p\n", i, p);
 105         return i;
 106 }
 107 EXPORT_SYMBOL(p9_idpool_get);
 108
 109 /**
 110  * p9_idpool_put - release numeric id from pool
 111  * @id: numeric id which is being released
 112  * @p: pool to release id into
 113  *
 114  * Bugs: This seems to be an awful generic function, should it be in idr.c with
 115  *            the lock included in struct idr?
 116  */
 117
 118 void p9_idpool_put(int id, struct p9_idpool *p)
 119 {
 120         unsigned long flags;
 121
 122         p9_debug(P9_DEBUG_MUX, " id %d pool %p\n", id, p);
 123
 124         spin_lock_irqsave(&p->lock, flags);
 125         idr_remove(&p->pool, id);
 126         spin_unlock_irqrestore(&p->lock, flags);
 127 }
 128 EXPORT_SYMBOL(p9_idpool_put);
 129
 130 /**
 131  * p9_idpool_check - check if the specified id is available
 132  * @id: id to check
 133  * @p: pool to check
 134  */
 135
 136 int p9_idpool_check(int id, struct p9_idpool *p)
 137 {
 138         return idr_find(&p->pool, id) != NULL;
 139 }
 140 EXPORT_SYMBOL(p9_idpool_check);
 141