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
  42 struct 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
  52 struct 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 }
  65 EXPORT_SYMBOL(p9_idpool_create);
  66
  67 /**
  68  * p9_idpool_destroy - create a new per-connection id pool
  69  * @p: idpool to destory
  70  */
  71
  72 void p9_idpool_destroy(struct p9_idpool *p)
  73 {
  74         idr_destroy(&p->pool);
  75         kfree(p);
  76 }
  77 EXPORT_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
  87 int p9_idpool_get(struct p9_idpool *p)
  88 {
  89         int i = 0;
  90         int error;
  91         unsigned long flags;
  92
  93 retry:
  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 }
 111 EXPORT_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
 122 void 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 }
 132 EXPORT_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
 140 int p9_idpool_check(int id, struct p9_idpool *p)
 141 {
 142         return idr_find(&p->pool, id) != NULL;
 143 }
 144 EXPORT_SYMBOL(p9_idpool_check);
 145