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 43struct 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 53struct 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} 66EXPORT_SYMBOL(p9_idpool_create); 67 68/** 69 * p9_idpool_destroy - create a new per-connection id pool 70 * @p: idpool to destory 71 */ 72 73void p9_idpool_destroy(struct p9_idpool *p) 74{ 75 idr_destroy(&p->pool); 76 kfree(p); 77} 78EXPORT_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 88int p9_idpool_get(struct p9_idpool *p) 89{ 90 int i = 0; 91 int error; 92 unsigned long flags; 93 94retry: 95 if (idr_pre_get(&p->pool, GFP_KERNEL) == 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} 112EXPORT_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 123void 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} 133EXPORT_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 141int p9_idpool_check(int id, struct p9_idpool *p) 142{ 143 return idr_find(&p->pool, id) != NULL; 144} 145EXPORT_SYMBOL(p9_idpool_check); 146