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 struct p9_idpool {
  36         struct semaphore lock;
  37         struct idr pool;
  38 };
  39
  40 struct p9_idpool *p9_idpool_create(void)
  41 {
  42         struct p9_idpool *p;
  43
  44         p = kmalloc(sizeof(struct p9_idpool), GFP_KERNEL);
  45         if (!p)
  46                 return ERR_PTR(-ENOMEM);
  47
  48         init_MUTEX(&p->lock);
  49         idr_init(&p->pool);
  50
  51         return p;
  52 }
  53 EXPORT_SYMBOL(p9_idpool_create);
  54
  55 void p9_idpool_destroy(struct p9_idpool *p)
  56 {
  57         idr_destroy(&p->pool);
  58         kfree(p);
  59 }
  60 EXPORT_SYMBOL(p9_idpool_destroy);
  61
  62 /**
  63  * p9_idpool_get - allocate numeric id from pool
  64  * @p - pool to allocate from
  65  *
  66  * XXX - This seems to be an awful generic function, should it be in idr.c with
  67  *            the lock included in struct idr?
  68  */
  69
  70 int p9_idpool_get(struct p9_idpool *p)
  71 {
  72         int i = 0;
  73         int error;
  74
  75 retry:
  76         if (idr_pre_get(&p->pool, GFP_KERNEL) == 0)
  77                 return 0;
  78
  79         if (down_interruptible(&p->lock) == -EINTR) {
  80                 P9_EPRINTK(KERN_WARNING, "Interrupted while locking\n");
  81                 return -1;
  82         }
  83
  84         /* no need to store exactly p, we just need something non-null */
  85         error = idr_get_new(&p->pool, p, &i);
  86         up(&p->lock);
  87
  88         if (error == -EAGAIN)
  89                 goto retry;
  90         else if (error)
  91                 return -1;
  92
  93         return i;
  94 }
  95 EXPORT_SYMBOL(p9_idpool_get);
  96
  97 /**
  98  * p9_idpool_put - release numeric id from pool
  99  * @p - pool to allocate from
 100  *
 101  * XXX - This seems to be an awful generic function, should it be in idr.c with
 102  *            the lock included in struct idr?
 103  */
 104
 105 void p9_idpool_put(int id, struct p9_idpool *p)
 106 {
 107         if (down_interruptible(&p->lock) == -EINTR) {
 108                 P9_EPRINTK(KERN_WARNING, "Interrupted while locking\n");
 109                 return;
 110         }
 111         idr_remove(&p->pool, id);
 112         up(&p->lock);
 113 }
 114 EXPORT_SYMBOL(p9_idpool_put);
 115
 116 /**
 117  * p9_idpool_check - check if the specified id is available
 118  * @id - id to check
 119  * @p - pool
 120  */
 121 int p9_idpool_check(int id, struct p9_idpool *p)
 122 {
 123         return idr_find(&p->pool, id) != NULL;
 124 }
 125 EXPORT_SYMBOL(p9_idpool_check);