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 = 0;
  91         int error;
  92         unsigned long flags;
  93
  94 retry:
  95         if (idr_pre_get(&p->pool, GFP_NOFS) == 0)
  96                 return 0;
  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_DPRINTK(P9_DEBUG_MUX, " id %d pool %p\n", i, p);
 110         return i;
 111 }
 112 EXPORT_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
 123 void p9_idpool_put(int id, struct p9_idpool *p)
 124 {
 125         unsigned long flags;
 126
 127         P9_DPRINTK(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 }
 133 EXPORT_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
 141 int p9_idpool_check(int id, struct p9_idpool *p)
 142 {
 143         return idr_find(&p->pool, id) != NULL;
 144 }
 145 EXPORT_SYMBOL(p9_idpool_check);
 146