Showing error 1251

User: Jiri Slaby
Error type: Leaving function in locked state
Error type description: Some lock is not unlocked on all paths of a function, so it is leaked
File location: drivers/char/misc.c
Line in file: 72
Project: Linux Kernel
Project version: 2.6.28
Tools: Stanse (1.2)
Entered: 2012-05-21 20:30:05 UTC

Source: 

  1/*
  2 * linux/drivers/char/misc.c
  3 *
  4 * Generic misc open routine by Johan Myreen
  5 *
  6 * Based on code from Linus
  7 *
  8 * Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's
  9 *   changes incorporated into 0.97pl4
 10 *   by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92)
 11 *   See busmouse.c for particulars.
 12 *
 13 * Made things a lot mode modular - easy to compile in just one or two
 14 * of the misc drivers, as they are now completely independent. Linus.
 15 *
 16 * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk>
 17 *
 18 * Fixed a failing symbol register to free the device registration
 19 *                Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96
 20 *
 21 * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96
 22 *
 23 * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96
 24 *
 25 * Handling of mouse minor numbers for kerneld:
 26 *  Idea by Jacques Gelinas <jack@solucorp.qc.ca>,
 27 *  adapted by Bjorn Ekwall <bj0rn@blox.se>
 28 *  corrected by Alan Cox <alan@lxorguk.ukuu.org.uk>
 29 *
 30 * Changes for kmod (from kerneld):
 31 *        Cyrus Durgin <cider@speakeasy.org>
 32 *
 33 * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au>  10-Jan-1998
 34 */
 35
 36#include <linux/module.h>
 37
 38#include <linux/fs.h>
 39#include <linux/errno.h>
 40#include <linux/miscdevice.h>
 41#include <linux/kernel.h>
 42#include <linux/major.h>
 43#include <linux/slab.h>
 44#include <linux/mutex.h>
 45#include <linux/proc_fs.h>
 46#include <linux/seq_file.h>
 47#include <linux/stat.h>
 48#include <linux/init.h>
 49#include <linux/device.h>
 50#include <linux/tty.h>
 51#include <linux/kmod.h>
 52#include <linux/smp_lock.h>
 53
 54/*
 55 * Head entry for the doubly linked miscdevice list
 56 */
 57static LIST_HEAD(misc_list);
 58static DEFINE_MUTEX(misc_mtx);
 59
 60/*
 61 * Assigned numbers, used for dynamic minors
 62 */
 63#define DYNAMIC_MINORS 64 /* like dynamic majors */
 64static unsigned char misc_minors[DYNAMIC_MINORS / 8];
 65
 66extern int pmu_device_init(void);
 67
 68#ifdef CONFIG_PROC_FS
 69static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
 70{
 71        mutex_lock(&misc_mtx);
 72        return seq_list_start(&misc_list, *pos);
 73}
 74
 75static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 76{
 77        return seq_list_next(v, &misc_list, pos);
 78}
 79
 80static void misc_seq_stop(struct seq_file *seq, void *v)
 81{
 82        mutex_unlock(&misc_mtx);
 83}
 84
 85static int misc_seq_show(struct seq_file *seq, void *v)
 86{
 87        const struct miscdevice *p = list_entry(v, struct miscdevice, list);
 88
 89        seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
 90        return 0;
 91}
 92
 93
 94static struct seq_operations misc_seq_ops = {
 95        .start = misc_seq_start,
 96        .next  = misc_seq_next,
 97        .stop  = misc_seq_stop,
 98        .show  = misc_seq_show,
 99};
100
101static int misc_seq_open(struct inode *inode, struct file *file)
102{
103        return seq_open(file, &misc_seq_ops);
104}
105
106static const struct file_operations misc_proc_fops = {
107        .owner         = THIS_MODULE,
108        .open    = misc_seq_open,
109        .read    = seq_read,
110        .llseek  = seq_lseek,
111        .release = seq_release,
112};
113#endif
114
115static int misc_open(struct inode * inode, struct file * file)
116{
117        int minor = iminor(inode);
118        struct miscdevice *c;
119        int err = -ENODEV;
120        const struct file_operations *old_fops, *new_fops = NULL;
121        
122        lock_kernel();
123        mutex_lock(&misc_mtx);
124        
125        list_for_each_entry(c, &misc_list, list) {
126                if (c->minor == minor) {
127                        new_fops = fops_get(c->fops);                
128                        break;
129                }
130        }
131                
132        if (!new_fops) {
133                mutex_unlock(&misc_mtx);
134                request_module("char-major-%d-%d", MISC_MAJOR, minor);
135                mutex_lock(&misc_mtx);
136
137                list_for_each_entry(c, &misc_list, list) {
138                        if (c->minor == minor) {
139                                new_fops = fops_get(c->fops);
140                                break;
141                        }
142                }
143                if (!new_fops)
144                        goto fail;
145        }
146
147        err = 0;
148        old_fops = file->f_op;
149        file->f_op = new_fops;
150        if (file->f_op->open) {
151                err=file->f_op->open(inode,file);
152                if (err) {
153                        fops_put(file->f_op);
154                        file->f_op = fops_get(old_fops);
155                }
156        }
157        fops_put(old_fops);
158fail:
159        mutex_unlock(&misc_mtx);
160        unlock_kernel();
161        return err;
162}
163
164static struct class *misc_class;
165
166static const struct file_operations misc_fops = {
167        .owner                = THIS_MODULE,
168        .open                = misc_open,
169};
170
171
172/**
173 *        misc_register        -        register a miscellaneous device
174 *        @misc: device structure
175 *        
176 *        Register a miscellaneous device with the kernel. If the minor
177 *        number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
178 *        and placed in the minor field of the structure. For other cases
179 *        the minor number requested is used.
180 *
181 *        The structure passed is linked into the kernel and may not be
182 *        destroyed until it has been unregistered.
183 *
184 *        A zero is returned on success and a negative errno code for
185 *        failure.
186 */
187 
188int misc_register(struct miscdevice * misc)
189{
190        struct miscdevice *c;
191        dev_t dev;
192        int err = 0;
193
194        INIT_LIST_HEAD(&misc->list);
195
196        mutex_lock(&misc_mtx);
197        list_for_each_entry(c, &misc_list, list) {
198                if (c->minor == misc->minor) {
199                        mutex_unlock(&misc_mtx);
200                        return -EBUSY;
201                }
202        }
203
204        if (misc->minor == MISC_DYNAMIC_MINOR) {
205                int i = DYNAMIC_MINORS;
206                while (--i >= 0)
207                        if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
208                                break;
209                if (i<0) {
210                        mutex_unlock(&misc_mtx);
211                        return -EBUSY;
212                }
213                misc->minor = i;
214        }
215
216        if (misc->minor < DYNAMIC_MINORS)
217                misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7);
218        dev = MKDEV(MISC_MAJOR, misc->minor);
219
220        misc->this_device = device_create(misc_class, misc->parent, dev, NULL,
221                                          "%s", misc->name);
222        if (IS_ERR(misc->this_device)) {
223                err = PTR_ERR(misc->this_device);
224                goto out;
225        }
226
227        /*
228         * Add it to the front, so that later devices can "override"
229         * earlier defaults
230         */
231        list_add(&misc->list, &misc_list);
232 out:
233        mutex_unlock(&misc_mtx);
234        return err;
235}
236
237/**
238 *        misc_deregister - unregister a miscellaneous device
239 *        @misc: device to unregister
240 *
241 *        Unregister a miscellaneous device that was previously
242 *        successfully registered with misc_register(). Success
243 *        is indicated by a zero return, a negative errno code
244 *        indicates an error.
245 */
246
247int misc_deregister(struct miscdevice *misc)
248{
249        int i = misc->minor;
250
251        if (list_empty(&misc->list))
252                return -EINVAL;
253
254        mutex_lock(&misc_mtx);
255        list_del(&misc->list);
256        device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
257        if (i < DYNAMIC_MINORS && i>0) {
258                misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
259        }
260        mutex_unlock(&misc_mtx);
261        return 0;
262}
263
264EXPORT_SYMBOL(misc_register);
265EXPORT_SYMBOL(misc_deregister);
266
267static int __init misc_init(void)
268{
269        int err;
270
271#ifdef CONFIG_PROC_FS
272        proc_create("misc", 0, NULL, &misc_proc_fops);
273#endif
274        misc_class = class_create(THIS_MODULE, "misc");
275        err = PTR_ERR(misc_class);
276        if (IS_ERR(misc_class))
277                goto fail_remove;
278
279        err = -EIO;
280        if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
281                goto fail_printk;
282        return 0;
283
284fail_printk:
285        printk("unable to get major %d for misc devices\n", MISC_MAJOR);
286        class_destroy(misc_class);
287fail_remove:
288        remove_proc_entry("misc", NULL);
289        return err;
290}
291subsys_initcall(misc_init);
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