ia64/linux-2.6.18-xen.hg

view fs/char_dev.c @ 452:c7ed6fe5dca0

kexec: dont initialise regions in reserve_memory()

There is no need to initialise efi_memmap_res and boot_param_res in
reserve_memory() for the initial xen domain as it is done in
machine_kexec_setup_resources() using values from the kexec hypercall.

Signed-off-by: Simon Horman <horms@verge.net.au>
author Keir Fraser <keir.fraser@citrix.com>
date Thu Feb 28 10:55:18 2008 +0000 (2008-02-28)
parents 831230e53067
children
line source
1 /*
2 * linux/fs/char_dev.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
7 #include <linux/init.h>
8 #include <linux/fs.h>
9 #include <linux/slab.h>
10 #include <linux/string.h>
12 #include <linux/major.h>
13 #include <linux/errno.h>
14 #include <linux/module.h>
15 #include <linux/smp_lock.h>
16 #include <linux/seq_file.h>
18 #include <linux/kobject.h>
19 #include <linux/kobj_map.h>
20 #include <linux/cdev.h>
21 #include <linux/mutex.h>
23 #ifdef CONFIG_KMOD
24 #include <linux/kmod.h>
25 #endif
27 static struct kobj_map *cdev_map;
29 static DEFINE_MUTEX(chrdevs_lock);
31 static struct char_device_struct {
32 struct char_device_struct *next;
33 unsigned int major;
34 unsigned int baseminor;
35 int minorct;
36 char name[64];
37 struct file_operations *fops;
38 struct cdev *cdev; /* will die */
39 } *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
41 /* index in the above */
42 static inline int major_to_index(int major)
43 {
44 return major % CHRDEV_MAJOR_HASH_SIZE;
45 }
47 #ifdef CONFIG_PROC_FS
49 void chrdev_show(struct seq_file *f, off_t offset)
50 {
51 struct char_device_struct *cd;
53 if (offset < CHRDEV_MAJOR_HASH_SIZE) {
54 mutex_lock(&chrdevs_lock);
55 for (cd = chrdevs[offset]; cd; cd = cd->next)
56 seq_printf(f, "%3d %s\n", cd->major, cd->name);
57 mutex_unlock(&chrdevs_lock);
58 }
59 }
61 #endif /* CONFIG_PROC_FS */
63 /*
64 * Register a single major with a specified minor range.
65 *
66 * If major == 0 this functions will dynamically allocate a major and return
67 * its number.
68 *
69 * If major > 0 this function will attempt to reserve the passed range of
70 * minors and will return zero on success.
71 *
72 * Returns a -ve errno on failure.
73 */
74 static struct char_device_struct *
75 __register_chrdev_region(unsigned int major, unsigned int baseminor,
76 int minorct, const char *name)
77 {
78 struct char_device_struct *cd, **cp;
79 int ret = 0;
80 int i;
82 cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
83 if (cd == NULL)
84 return ERR_PTR(-ENOMEM);
86 mutex_lock(&chrdevs_lock);
88 /* temporary */
89 if (major == 0) {
90 for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
91 if (chrdevs[i] == NULL)
92 break;
93 }
95 if (i == 0) {
96 ret = -EBUSY;
97 goto out;
98 }
99 major = i;
100 ret = major;
101 }
103 cd->major = major;
104 cd->baseminor = baseminor;
105 cd->minorct = minorct;
106 strncpy(cd->name,name, 64);
108 i = major_to_index(major);
110 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
111 if ((*cp)->major > major ||
112 ((*cp)->major == major && (*cp)->baseminor >= baseminor))
113 break;
114 if (*cp && (*cp)->major == major &&
115 (*cp)->baseminor < baseminor + minorct) {
116 ret = -EBUSY;
117 goto out;
118 }
119 cd->next = *cp;
120 *cp = cd;
121 mutex_unlock(&chrdevs_lock);
122 return cd;
123 out:
124 mutex_unlock(&chrdevs_lock);
125 kfree(cd);
126 return ERR_PTR(ret);
127 }
129 static struct char_device_struct *
130 __unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
131 {
132 struct char_device_struct *cd = NULL, **cp;
133 int i = major_to_index(major);
135 mutex_lock(&chrdevs_lock);
136 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
137 if ((*cp)->major == major &&
138 (*cp)->baseminor == baseminor &&
139 (*cp)->minorct == minorct)
140 break;
141 if (*cp) {
142 cd = *cp;
143 *cp = cd->next;
144 }
145 mutex_unlock(&chrdevs_lock);
146 return cd;
147 }
149 int register_chrdev_region(dev_t from, unsigned count, const char *name)
150 {
151 struct char_device_struct *cd;
152 dev_t to = from + count;
153 dev_t n, next;
155 for (n = from; n < to; n = next) {
156 next = MKDEV(MAJOR(n)+1, 0);
157 if (next > to)
158 next = to;
159 cd = __register_chrdev_region(MAJOR(n), MINOR(n),
160 next - n, name);
161 if (IS_ERR(cd))
162 goto fail;
163 }
164 return 0;
165 fail:
166 to = n;
167 for (n = from; n < to; n = next) {
168 next = MKDEV(MAJOR(n)+1, 0);
169 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
170 }
171 return PTR_ERR(cd);
172 }
174 int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
175 const char *name)
176 {
177 struct char_device_struct *cd;
178 cd = __register_chrdev_region(0, baseminor, count, name);
179 if (IS_ERR(cd))
180 return PTR_ERR(cd);
181 *dev = MKDEV(cd->major, cd->baseminor);
182 return 0;
183 }
185 /**
186 * register_chrdev() - Register a major number for character devices.
187 * @major: major device number or 0 for dynamic allocation
188 * @name: name of this range of devices
189 * @fops: file operations associated with this devices
190 *
191 * If @major == 0 this functions will dynamically allocate a major and return
192 * its number.
193 *
194 * If @major > 0 this function will attempt to reserve a device with the given
195 * major number and will return zero on success.
196 *
197 * Returns a -ve errno on failure.
198 *
199 * The name of this device has nothing to do with the name of the device in
200 * /dev. It only helps to keep track of the different owners of devices. If
201 * your module name has only one type of devices it's ok to use e.g. the name
202 * of the module here.
203 *
204 * This function registers a range of 256 minor numbers. The first minor number
205 * is 0.
206 */
207 int register_chrdev(unsigned int major, const char *name,
208 const struct file_operations *fops)
209 {
210 struct char_device_struct *cd;
211 struct cdev *cdev;
212 char *s;
213 int err = -ENOMEM;
215 cd = __register_chrdev_region(major, 0, 256, name);
216 if (IS_ERR(cd))
217 return PTR_ERR(cd);
219 cdev = cdev_alloc();
220 if (!cdev)
221 goto out2;
223 cdev->owner = fops->owner;
224 cdev->ops = fops;
225 kobject_set_name(&cdev->kobj, "%s", name);
226 for (s = strchr(kobject_name(&cdev->kobj),'/'); s; s = strchr(s, '/'))
227 *s = '!';
229 err = cdev_add(cdev, MKDEV(cd->major, 0), 256);
230 if (err)
231 goto out;
233 cd->cdev = cdev;
235 return major ? 0 : cd->major;
236 out:
237 kobject_put(&cdev->kobj);
238 out2:
239 kfree(__unregister_chrdev_region(cd->major, 0, 256));
240 return err;
241 }
243 void unregister_chrdev_region(dev_t from, unsigned count)
244 {
245 dev_t to = from + count;
246 dev_t n, next;
248 for (n = from; n < to; n = next) {
249 next = MKDEV(MAJOR(n)+1, 0);
250 if (next > to)
251 next = to;
252 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
253 }
254 }
256 int unregister_chrdev(unsigned int major, const char *name)
257 {
258 struct char_device_struct *cd;
259 cd = __unregister_chrdev_region(major, 0, 256);
260 if (cd && cd->cdev)
261 cdev_del(cd->cdev);
262 kfree(cd);
263 return 0;
264 }
266 static DEFINE_SPINLOCK(cdev_lock);
268 static struct kobject *cdev_get(struct cdev *p)
269 {
270 struct module *owner = p->owner;
271 struct kobject *kobj;
273 if (owner && !try_module_get(owner))
274 return NULL;
275 kobj = kobject_get(&p->kobj);
276 if (!kobj)
277 module_put(owner);
278 return kobj;
279 }
281 void cdev_put(struct cdev *p)
282 {
283 if (p) {
284 struct module *owner = p->owner;
285 kobject_put(&p->kobj);
286 module_put(owner);
287 }
288 }
290 /*
291 * Called every time a character special file is opened
292 */
293 int chrdev_open(struct inode * inode, struct file * filp)
294 {
295 struct cdev *p;
296 struct cdev *new = NULL;
297 int ret = 0;
299 spin_lock(&cdev_lock);
300 p = inode->i_cdev;
301 if (!p) {
302 struct kobject *kobj;
303 int idx;
304 spin_unlock(&cdev_lock);
305 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
306 if (!kobj)
307 return -ENXIO;
308 new = container_of(kobj, struct cdev, kobj);
309 spin_lock(&cdev_lock);
310 p = inode->i_cdev;
311 if (!p) {
312 inode->i_cdev = p = new;
313 inode->i_cindex = idx;
314 list_add(&inode->i_devices, &p->list);
315 new = NULL;
316 } else if (!cdev_get(p))
317 ret = -ENXIO;
318 } else if (!cdev_get(p))
319 ret = -ENXIO;
320 spin_unlock(&cdev_lock);
321 cdev_put(new);
322 if (ret)
323 return ret;
324 filp->f_op = fops_get(p->ops);
325 if (!filp->f_op) {
326 cdev_put(p);
327 return -ENXIO;
328 }
329 if (filp->f_op->open) {
330 lock_kernel();
331 ret = filp->f_op->open(inode,filp);
332 unlock_kernel();
333 }
334 if (ret)
335 cdev_put(p);
336 return ret;
337 }
339 void cd_forget(struct inode *inode)
340 {
341 spin_lock(&cdev_lock);
342 list_del_init(&inode->i_devices);
343 inode->i_cdev = NULL;
344 spin_unlock(&cdev_lock);
345 }
347 static void cdev_purge(struct cdev *cdev)
348 {
349 spin_lock(&cdev_lock);
350 while (!list_empty(&cdev->list)) {
351 struct inode *inode;
352 inode = container_of(cdev->list.next, struct inode, i_devices);
353 list_del_init(&inode->i_devices);
354 inode->i_cdev = NULL;
355 }
356 spin_unlock(&cdev_lock);
357 }
359 /*
360 * Dummy default file-operations: the only thing this does
361 * is contain the open that then fills in the correct operations
362 * depending on the special file...
363 */
364 const struct file_operations def_chr_fops = {
365 .open = chrdev_open,
366 };
368 static struct kobject *exact_match(dev_t dev, int *part, void *data)
369 {
370 struct cdev *p = data;
371 return &p->kobj;
372 }
374 static int exact_lock(dev_t dev, void *data)
375 {
376 struct cdev *p = data;
377 return cdev_get(p) ? 0 : -1;
378 }
380 int cdev_add(struct cdev *p, dev_t dev, unsigned count)
381 {
382 p->dev = dev;
383 p->count = count;
384 return kobj_map(cdev_map, dev, count, NULL, exact_match, exact_lock, p);
385 }
387 static void cdev_unmap(dev_t dev, unsigned count)
388 {
389 kobj_unmap(cdev_map, dev, count);
390 }
392 void cdev_del(struct cdev *p)
393 {
394 cdev_unmap(p->dev, p->count);
395 kobject_put(&p->kobj);
396 }
399 static void cdev_default_release(struct kobject *kobj)
400 {
401 struct cdev *p = container_of(kobj, struct cdev, kobj);
402 cdev_purge(p);
403 }
405 static void cdev_dynamic_release(struct kobject *kobj)
406 {
407 struct cdev *p = container_of(kobj, struct cdev, kobj);
408 cdev_purge(p);
409 kfree(p);
410 }
412 static struct kobj_type ktype_cdev_default = {
413 .release = cdev_default_release,
414 };
416 static struct kobj_type ktype_cdev_dynamic = {
417 .release = cdev_dynamic_release,
418 };
420 struct cdev *cdev_alloc(void)
421 {
422 struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
423 if (p) {
424 p->kobj.ktype = &ktype_cdev_dynamic;
425 INIT_LIST_HEAD(&p->list);
426 kobject_init(&p->kobj);
427 }
428 return p;
429 }
431 void cdev_init(struct cdev *cdev, const struct file_operations *fops)
432 {
433 memset(cdev, 0, sizeof *cdev);
434 INIT_LIST_HEAD(&cdev->list);
435 cdev->kobj.ktype = &ktype_cdev_default;
436 kobject_init(&cdev->kobj);
437 cdev->ops = fops;
438 }
440 static struct kobject *base_probe(dev_t dev, int *part, void *data)
441 {
442 if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
443 /* Make old-style 2.4 aliases work */
444 request_module("char-major-%d", MAJOR(dev));
445 return NULL;
446 }
448 void __init chrdev_init(void)
449 {
450 cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
451 }
454 /* Let modules do char dev stuff */
455 EXPORT_SYMBOL(register_chrdev_region);
456 EXPORT_SYMBOL(unregister_chrdev_region);
457 EXPORT_SYMBOL(alloc_chrdev_region);
458 EXPORT_SYMBOL(cdev_init);
459 EXPORT_SYMBOL(cdev_alloc);
460 EXPORT_SYMBOL(cdev_del);
461 EXPORT_SYMBOL(cdev_add);
462 EXPORT_SYMBOL(register_chrdev);
463 EXPORT_SYMBOL(unregister_chrdev);