xref: /openbmc/linux/fs/proc/generic.c (revision 9ac8d3fb)
1 /*
2  * proc/fs/generic.c --- generic routines for the proc-fs
3  *
4  * This file contains generic proc-fs routines for handling
5  * directories and files.
6  *
7  * Copyright (C) 1991, 1992 Linus Torvalds.
8  * Copyright (C) 1997 Theodore Ts'o
9  */
10 
11 #include <linux/errno.h>
12 #include <linux/time.h>
13 #include <linux/proc_fs.h>
14 #include <linux/stat.h>
15 #include <linux/module.h>
16 #include <linux/mount.h>
17 #include <linux/smp_lock.h>
18 #include <linux/init.h>
19 #include <linux/idr.h>
20 #include <linux/namei.h>
21 #include <linux/bitops.h>
22 #include <linux/spinlock.h>
23 #include <linux/completion.h>
24 #include <asm/uaccess.h>
25 
26 #include "internal.h"
27 
28 DEFINE_SPINLOCK(proc_subdir_lock);
29 
30 static int proc_match(int len, const char *name, struct proc_dir_entry *de)
31 {
32 	if (de->namelen != len)
33 		return 0;
34 	return !memcmp(name, de->name, len);
35 }
36 
37 /* buffer size is one page but our output routines use some slack for overruns */
38 #define PROC_BLOCK_SIZE	(PAGE_SIZE - 1024)
39 
40 static ssize_t
41 proc_file_read(struct file *file, char __user *buf, size_t nbytes,
42 	       loff_t *ppos)
43 {
44 	struct inode * inode = file->f_path.dentry->d_inode;
45 	char 	*page;
46 	ssize_t	retval=0;
47 	int	eof=0;
48 	ssize_t	n, count;
49 	char	*start;
50 	struct proc_dir_entry * dp;
51 	unsigned long long pos;
52 
53 	/*
54 	 * Gaah, please just use "seq_file" instead. The legacy /proc
55 	 * interfaces cut loff_t down to off_t for reads, and ignore
56 	 * the offset entirely for writes..
57 	 */
58 	pos = *ppos;
59 	if (pos > MAX_NON_LFS)
60 		return 0;
61 	if (nbytes > MAX_NON_LFS - pos)
62 		nbytes = MAX_NON_LFS - pos;
63 
64 	dp = PDE(inode);
65 	if (!(page = (char*) __get_free_page(GFP_TEMPORARY)))
66 		return -ENOMEM;
67 
68 	while ((nbytes > 0) && !eof) {
69 		count = min_t(size_t, PROC_BLOCK_SIZE, nbytes);
70 
71 		start = NULL;
72 		if (dp->read_proc) {
73 			/*
74 			 * How to be a proc read function
75 			 * ------------------------------
76 			 * Prototype:
77 			 *    int f(char *buffer, char **start, off_t offset,
78 			 *          int count, int *peof, void *dat)
79 			 *
80 			 * Assume that the buffer is "count" bytes in size.
81 			 *
82 			 * If you know you have supplied all the data you
83 			 * have, set *peof.
84 			 *
85 			 * You have three ways to return data:
86 			 * 0) Leave *start = NULL.  (This is the default.)
87 			 *    Put the data of the requested offset at that
88 			 *    offset within the buffer.  Return the number (n)
89 			 *    of bytes there are from the beginning of the
90 			 *    buffer up to the last byte of data.  If the
91 			 *    number of supplied bytes (= n - offset) is
92 			 *    greater than zero and you didn't signal eof
93 			 *    and the reader is prepared to take more data
94 			 *    you will be called again with the requested
95 			 *    offset advanced by the number of bytes
96 			 *    absorbed.  This interface is useful for files
97 			 *    no larger than the buffer.
98 			 * 1) Set *start = an unsigned long value less than
99 			 *    the buffer address but greater than zero.
100 			 *    Put the data of the requested offset at the
101 			 *    beginning of the buffer.  Return the number of
102 			 *    bytes of data placed there.  If this number is
103 			 *    greater than zero and you didn't signal eof
104 			 *    and the reader is prepared to take more data
105 			 *    you will be called again with the requested
106 			 *    offset advanced by *start.  This interface is
107 			 *    useful when you have a large file consisting
108 			 *    of a series of blocks which you want to count
109 			 *    and return as wholes.
110 			 *    (Hack by Paul.Russell@rustcorp.com.au)
111 			 * 2) Set *start = an address within the buffer.
112 			 *    Put the data of the requested offset at *start.
113 			 *    Return the number of bytes of data placed there.
114 			 *    If this number is greater than zero and you
115 			 *    didn't signal eof and the reader is prepared to
116 			 *    take more data you will be called again with the
117 			 *    requested offset advanced by the number of bytes
118 			 *    absorbed.
119 			 */
120 			n = dp->read_proc(page, &start, *ppos,
121 					  count, &eof, dp->data);
122 		} else
123 			break;
124 
125 		if (n == 0)   /* end of file */
126 			break;
127 		if (n < 0) {  /* error */
128 			if (retval == 0)
129 				retval = n;
130 			break;
131 		}
132 
133 		if (start == NULL) {
134 			if (n > PAGE_SIZE) {
135 				printk(KERN_ERR
136 				       "proc_file_read: Apparent buffer overflow!\n");
137 				n = PAGE_SIZE;
138 			}
139 			n -= *ppos;
140 			if (n <= 0)
141 				break;
142 			if (n > count)
143 				n = count;
144 			start = page + *ppos;
145 		} else if (start < page) {
146 			if (n > PAGE_SIZE) {
147 				printk(KERN_ERR
148 				       "proc_file_read: Apparent buffer overflow!\n");
149 				n = PAGE_SIZE;
150 			}
151 			if (n > count) {
152 				/*
153 				 * Don't reduce n because doing so might
154 				 * cut off part of a data block.
155 				 */
156 				printk(KERN_WARNING
157 				       "proc_file_read: Read count exceeded\n");
158 			}
159 		} else /* start >= page */ {
160 			unsigned long startoff = (unsigned long)(start - page);
161 			if (n > (PAGE_SIZE - startoff)) {
162 				printk(KERN_ERR
163 				       "proc_file_read: Apparent buffer overflow!\n");
164 				n = PAGE_SIZE - startoff;
165 			}
166 			if (n > count)
167 				n = count;
168 		}
169 
170  		n -= copy_to_user(buf, start < page ? page : start, n);
171 		if (n == 0) {
172 			if (retval == 0)
173 				retval = -EFAULT;
174 			break;
175 		}
176 
177 		*ppos += start < page ? (unsigned long)start : n;
178 		nbytes -= n;
179 		buf += n;
180 		retval += n;
181 	}
182 	free_page((unsigned long) page);
183 	return retval;
184 }
185 
186 static ssize_t
187 proc_file_write(struct file *file, const char __user *buffer,
188 		size_t count, loff_t *ppos)
189 {
190 	struct inode *inode = file->f_path.dentry->d_inode;
191 	struct proc_dir_entry * dp;
192 
193 	dp = PDE(inode);
194 
195 	if (!dp->write_proc)
196 		return -EIO;
197 
198 	/* FIXME: does this routine need ppos?  probably... */
199 	return dp->write_proc(file, buffer, count, dp->data);
200 }
201 
202 
203 static loff_t
204 proc_file_lseek(struct file *file, loff_t offset, int orig)
205 {
206 	loff_t retval = -EINVAL;
207 	switch (orig) {
208 	case 1:
209 		offset += file->f_pos;
210 	/* fallthrough */
211 	case 0:
212 		if (offset < 0 || offset > MAX_NON_LFS)
213 			break;
214 		file->f_pos = retval = offset;
215 	}
216 	return retval;
217 }
218 
219 static const struct file_operations proc_file_operations = {
220 	.llseek		= proc_file_lseek,
221 	.read		= proc_file_read,
222 	.write		= proc_file_write,
223 };
224 
225 static int proc_notify_change(struct dentry *dentry, struct iattr *iattr)
226 {
227 	struct inode *inode = dentry->d_inode;
228 	struct proc_dir_entry *de = PDE(inode);
229 	int error;
230 
231 	error = inode_change_ok(inode, iattr);
232 	if (error)
233 		goto out;
234 
235 	error = inode_setattr(inode, iattr);
236 	if (error)
237 		goto out;
238 
239 	de->uid = inode->i_uid;
240 	de->gid = inode->i_gid;
241 	de->mode = inode->i_mode;
242 out:
243 	return error;
244 }
245 
246 static int proc_getattr(struct vfsmount *mnt, struct dentry *dentry,
247 			struct kstat *stat)
248 {
249 	struct inode *inode = dentry->d_inode;
250 	struct proc_dir_entry *de = PROC_I(inode)->pde;
251 	if (de && de->nlink)
252 		inode->i_nlink = de->nlink;
253 
254 	generic_fillattr(inode, stat);
255 	return 0;
256 }
257 
258 static const struct inode_operations proc_file_inode_operations = {
259 	.setattr	= proc_notify_change,
260 };
261 
262 /*
263  * This function parses a name such as "tty/driver/serial", and
264  * returns the struct proc_dir_entry for "/proc/tty/driver", and
265  * returns "serial" in residual.
266  */
267 static int xlate_proc_name(const char *name,
268 			   struct proc_dir_entry **ret, const char **residual)
269 {
270 	const char     		*cp = name, *next;
271 	struct proc_dir_entry	*de;
272 	int			len;
273 	int 			rtn = 0;
274 
275 	de = *ret;
276 	if (!de)
277 		de = &proc_root;
278 
279 	spin_lock(&proc_subdir_lock);
280 	while (1) {
281 		next = strchr(cp, '/');
282 		if (!next)
283 			break;
284 
285 		len = next - cp;
286 		for (de = de->subdir; de ; de = de->next) {
287 			if (proc_match(len, cp, de))
288 				break;
289 		}
290 		if (!de) {
291 			rtn = -ENOENT;
292 			goto out;
293 		}
294 		cp += len + 1;
295 	}
296 	*residual = cp;
297 	*ret = de;
298 out:
299 	spin_unlock(&proc_subdir_lock);
300 	return rtn;
301 }
302 
303 static DEFINE_IDA(proc_inum_ida);
304 static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
305 
306 #define PROC_DYNAMIC_FIRST 0xF0000000U
307 
308 /*
309  * Return an inode number between PROC_DYNAMIC_FIRST and
310  * 0xffffffff, or zero on failure.
311  */
312 static unsigned int get_inode_number(void)
313 {
314 	unsigned int i;
315 	int error;
316 
317 retry:
318 	if (ida_pre_get(&proc_inum_ida, GFP_KERNEL) == 0)
319 		return 0;
320 
321 	spin_lock(&proc_inum_lock);
322 	error = ida_get_new(&proc_inum_ida, &i);
323 	spin_unlock(&proc_inum_lock);
324 	if (error == -EAGAIN)
325 		goto retry;
326 	else if (error)
327 		return 0;
328 
329 	if (i > UINT_MAX - PROC_DYNAMIC_FIRST) {
330 		spin_lock(&proc_inum_lock);
331 		ida_remove(&proc_inum_ida, i);
332 		spin_unlock(&proc_inum_lock);
333 		return 0;
334 	}
335 	return PROC_DYNAMIC_FIRST + i;
336 }
337 
338 static void release_inode_number(unsigned int inum)
339 {
340 	spin_lock(&proc_inum_lock);
341 	ida_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
342 	spin_unlock(&proc_inum_lock);
343 }
344 
345 static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
346 {
347 	nd_set_link(nd, PDE(dentry->d_inode)->data);
348 	return NULL;
349 }
350 
351 static const struct inode_operations proc_link_inode_operations = {
352 	.readlink	= generic_readlink,
353 	.follow_link	= proc_follow_link,
354 };
355 
356 /*
357  * As some entries in /proc are volatile, we want to
358  * get rid of unused dentries.  This could be made
359  * smarter: we could keep a "volatile" flag in the
360  * inode to indicate which ones to keep.
361  */
362 static int proc_delete_dentry(struct dentry * dentry)
363 {
364 	return 1;
365 }
366 
367 static struct dentry_operations proc_dentry_operations =
368 {
369 	.d_delete	= proc_delete_dentry,
370 };
371 
372 /*
373  * Don't create negative dentries here, return -ENOENT by hand
374  * instead.
375  */
376 struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir,
377 		struct dentry *dentry)
378 {
379 	struct inode *inode = NULL;
380 	int error = -ENOENT;
381 
382 	lock_kernel();
383 	spin_lock(&proc_subdir_lock);
384 	for (de = de->subdir; de ; de = de->next) {
385 		if (de->namelen != dentry->d_name.len)
386 			continue;
387 		if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
388 			unsigned int ino;
389 
390 			ino = de->low_ino;
391 			de_get(de);
392 			spin_unlock(&proc_subdir_lock);
393 			error = -EINVAL;
394 			inode = proc_get_inode(dir->i_sb, ino, de);
395 			goto out_unlock;
396 		}
397 	}
398 	spin_unlock(&proc_subdir_lock);
399 out_unlock:
400 	unlock_kernel();
401 
402 	if (inode) {
403 		dentry->d_op = &proc_dentry_operations;
404 		d_add(dentry, inode);
405 		return NULL;
406 	}
407 	if (de)
408 		de_put(de);
409 	return ERR_PTR(error);
410 }
411 
412 struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry,
413 		struct nameidata *nd)
414 {
415 	return proc_lookup_de(PDE(dir), dir, dentry);
416 }
417 
418 /*
419  * This returns non-zero if at EOF, so that the /proc
420  * root directory can use this and check if it should
421  * continue with the <pid> entries..
422  *
423  * Note that the VFS-layer doesn't care about the return
424  * value of the readdir() call, as long as it's non-negative
425  * for success..
426  */
427 int proc_readdir_de(struct proc_dir_entry *de, struct file *filp, void *dirent,
428 		filldir_t filldir)
429 {
430 	unsigned int ino;
431 	int i;
432 	struct inode *inode = filp->f_path.dentry->d_inode;
433 	int ret = 0;
434 
435 	lock_kernel();
436 
437 	ino = inode->i_ino;
438 	i = filp->f_pos;
439 	switch (i) {
440 		case 0:
441 			if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
442 				goto out;
443 			i++;
444 			filp->f_pos++;
445 			/* fall through */
446 		case 1:
447 			if (filldir(dirent, "..", 2, i,
448 				    parent_ino(filp->f_path.dentry),
449 				    DT_DIR) < 0)
450 				goto out;
451 			i++;
452 			filp->f_pos++;
453 			/* fall through */
454 		default:
455 			spin_lock(&proc_subdir_lock);
456 			de = de->subdir;
457 			i -= 2;
458 			for (;;) {
459 				if (!de) {
460 					ret = 1;
461 					spin_unlock(&proc_subdir_lock);
462 					goto out;
463 				}
464 				if (!i)
465 					break;
466 				de = de->next;
467 				i--;
468 			}
469 
470 			do {
471 				struct proc_dir_entry *next;
472 
473 				/* filldir passes info to user space */
474 				de_get(de);
475 				spin_unlock(&proc_subdir_lock);
476 				if (filldir(dirent, de->name, de->namelen, filp->f_pos,
477 					    de->low_ino, de->mode >> 12) < 0) {
478 					de_put(de);
479 					goto out;
480 				}
481 				spin_lock(&proc_subdir_lock);
482 				filp->f_pos++;
483 				next = de->next;
484 				de_put(de);
485 				de = next;
486 			} while (de);
487 			spin_unlock(&proc_subdir_lock);
488 	}
489 	ret = 1;
490 out:	unlock_kernel();
491 	return ret;
492 }
493 
494 int proc_readdir(struct file *filp, void *dirent, filldir_t filldir)
495 {
496 	struct inode *inode = filp->f_path.dentry->d_inode;
497 
498 	return proc_readdir_de(PDE(inode), filp, dirent, filldir);
499 }
500 
501 /*
502  * These are the generic /proc directory operations. They
503  * use the in-memory "struct proc_dir_entry" tree to parse
504  * the /proc directory.
505  */
506 static const struct file_operations proc_dir_operations = {
507 	.read			= generic_read_dir,
508 	.readdir		= proc_readdir,
509 };
510 
511 /*
512  * proc directories can do almost nothing..
513  */
514 static const struct inode_operations proc_dir_inode_operations = {
515 	.lookup		= proc_lookup,
516 	.getattr	= proc_getattr,
517 	.setattr	= proc_notify_change,
518 };
519 
520 static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp)
521 {
522 	unsigned int i;
523 	struct proc_dir_entry *tmp;
524 
525 	i = get_inode_number();
526 	if (i == 0)
527 		return -EAGAIN;
528 	dp->low_ino = i;
529 
530 	if (S_ISDIR(dp->mode)) {
531 		if (dp->proc_iops == NULL) {
532 			dp->proc_fops = &proc_dir_operations;
533 			dp->proc_iops = &proc_dir_inode_operations;
534 		}
535 		dir->nlink++;
536 	} else if (S_ISLNK(dp->mode)) {
537 		if (dp->proc_iops == NULL)
538 			dp->proc_iops = &proc_link_inode_operations;
539 	} else if (S_ISREG(dp->mode)) {
540 		if (dp->proc_fops == NULL)
541 			dp->proc_fops = &proc_file_operations;
542 		if (dp->proc_iops == NULL)
543 			dp->proc_iops = &proc_file_inode_operations;
544 	}
545 
546 	spin_lock(&proc_subdir_lock);
547 
548 	for (tmp = dir->subdir; tmp; tmp = tmp->next)
549 		if (strcmp(tmp->name, dp->name) == 0) {
550 			WARN(1, KERN_WARNING "proc_dir_entry '%s/%s' already registered\n",
551 				dir->name, dp->name);
552 			break;
553 		}
554 
555 	dp->next = dir->subdir;
556 	dp->parent = dir;
557 	dir->subdir = dp;
558 	spin_unlock(&proc_subdir_lock);
559 
560 	return 0;
561 }
562 
563 static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
564 					  const char *name,
565 					  mode_t mode,
566 					  nlink_t nlink)
567 {
568 	struct proc_dir_entry *ent = NULL;
569 	const char *fn = name;
570 	int len;
571 
572 	/* make sure name is valid */
573 	if (!name || !strlen(name)) goto out;
574 
575 	if (xlate_proc_name(name, parent, &fn) != 0)
576 		goto out;
577 
578 	/* At this point there must not be any '/' characters beyond *fn */
579 	if (strchr(fn, '/'))
580 		goto out;
581 
582 	len = strlen(fn);
583 
584 	ent = kmalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL);
585 	if (!ent) goto out;
586 
587 	memset(ent, 0, sizeof(struct proc_dir_entry));
588 	memcpy(((char *) ent) + sizeof(struct proc_dir_entry), fn, len + 1);
589 	ent->name = ((char *) ent) + sizeof(*ent);
590 	ent->namelen = len;
591 	ent->mode = mode;
592 	ent->nlink = nlink;
593 	atomic_set(&ent->count, 1);
594 	ent->pde_users = 0;
595 	spin_lock_init(&ent->pde_unload_lock);
596 	ent->pde_unload_completion = NULL;
597 	INIT_LIST_HEAD(&ent->pde_openers);
598  out:
599 	return ent;
600 }
601 
602 struct proc_dir_entry *proc_symlink(const char *name,
603 		struct proc_dir_entry *parent, const char *dest)
604 {
605 	struct proc_dir_entry *ent;
606 
607 	ent = __proc_create(&parent, name,
608 			  (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);
609 
610 	if (ent) {
611 		ent->data = kmalloc((ent->size=strlen(dest))+1, GFP_KERNEL);
612 		if (ent->data) {
613 			strcpy((char*)ent->data,dest);
614 			if (proc_register(parent, ent) < 0) {
615 				kfree(ent->data);
616 				kfree(ent);
617 				ent = NULL;
618 			}
619 		} else {
620 			kfree(ent);
621 			ent = NULL;
622 		}
623 	}
624 	return ent;
625 }
626 
627 struct proc_dir_entry *proc_mkdir_mode(const char *name, mode_t mode,
628 		struct proc_dir_entry *parent)
629 {
630 	struct proc_dir_entry *ent;
631 
632 	ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
633 	if (ent) {
634 		if (proc_register(parent, ent) < 0) {
635 			kfree(ent);
636 			ent = NULL;
637 		}
638 	}
639 	return ent;
640 }
641 
642 struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name,
643 		struct proc_dir_entry *parent)
644 {
645 	struct proc_dir_entry *ent;
646 
647 	ent = __proc_create(&parent, name, S_IFDIR | S_IRUGO | S_IXUGO, 2);
648 	if (ent) {
649 		ent->data = net;
650 		if (proc_register(parent, ent) < 0) {
651 			kfree(ent);
652 			ent = NULL;
653 		}
654 	}
655 	return ent;
656 }
657 EXPORT_SYMBOL_GPL(proc_net_mkdir);
658 
659 struct proc_dir_entry *proc_mkdir(const char *name,
660 		struct proc_dir_entry *parent)
661 {
662 	return proc_mkdir_mode(name, S_IRUGO | S_IXUGO, parent);
663 }
664 
665 struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode,
666 					 struct proc_dir_entry *parent)
667 {
668 	struct proc_dir_entry *ent;
669 	nlink_t nlink;
670 
671 	if (S_ISDIR(mode)) {
672 		if ((mode & S_IALLUGO) == 0)
673 			mode |= S_IRUGO | S_IXUGO;
674 		nlink = 2;
675 	} else {
676 		if ((mode & S_IFMT) == 0)
677 			mode |= S_IFREG;
678 		if ((mode & S_IALLUGO) == 0)
679 			mode |= S_IRUGO;
680 		nlink = 1;
681 	}
682 
683 	ent = __proc_create(&parent, name, mode, nlink);
684 	if (ent) {
685 		if (proc_register(parent, ent) < 0) {
686 			kfree(ent);
687 			ent = NULL;
688 		}
689 	}
690 	return ent;
691 }
692 
693 struct proc_dir_entry *proc_create_data(const char *name, mode_t mode,
694 					struct proc_dir_entry *parent,
695 					const struct file_operations *proc_fops,
696 					void *data)
697 {
698 	struct proc_dir_entry *pde;
699 	nlink_t nlink;
700 
701 	if (S_ISDIR(mode)) {
702 		if ((mode & S_IALLUGO) == 0)
703 			mode |= S_IRUGO | S_IXUGO;
704 		nlink = 2;
705 	} else {
706 		if ((mode & S_IFMT) == 0)
707 			mode |= S_IFREG;
708 		if ((mode & S_IALLUGO) == 0)
709 			mode |= S_IRUGO;
710 		nlink = 1;
711 	}
712 
713 	pde = __proc_create(&parent, name, mode, nlink);
714 	if (!pde)
715 		goto out;
716 	pde->proc_fops = proc_fops;
717 	pde->data = data;
718 	if (proc_register(parent, pde) < 0)
719 		goto out_free;
720 	return pde;
721 out_free:
722 	kfree(pde);
723 out:
724 	return NULL;
725 }
726 
727 void free_proc_entry(struct proc_dir_entry *de)
728 {
729 	unsigned int ino = de->low_ino;
730 
731 	if (ino < PROC_DYNAMIC_FIRST)
732 		return;
733 
734 	release_inode_number(ino);
735 
736 	if (S_ISLNK(de->mode))
737 		kfree(de->data);
738 	kfree(de);
739 }
740 
741 /*
742  * Remove a /proc entry and free it if it's not currently in use.
743  */
744 void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
745 {
746 	struct proc_dir_entry **p;
747 	struct proc_dir_entry *de = NULL;
748 	const char *fn = name;
749 	int len;
750 
751 	if (xlate_proc_name(name, &parent, &fn) != 0)
752 		return;
753 	len = strlen(fn);
754 
755 	spin_lock(&proc_subdir_lock);
756 	for (p = &parent->subdir; *p; p=&(*p)->next ) {
757 		if (proc_match(len, fn, *p)) {
758 			de = *p;
759 			*p = de->next;
760 			de->next = NULL;
761 			break;
762 		}
763 	}
764 	spin_unlock(&proc_subdir_lock);
765 	if (!de)
766 		return;
767 
768 	spin_lock(&de->pde_unload_lock);
769 	/*
770 	 * Stop accepting new callers into module. If you're
771 	 * dynamically allocating ->proc_fops, save a pointer somewhere.
772 	 */
773 	de->proc_fops = NULL;
774 	/* Wait until all existing callers into module are done. */
775 	if (de->pde_users > 0) {
776 		DECLARE_COMPLETION_ONSTACK(c);
777 
778 		if (!de->pde_unload_completion)
779 			de->pde_unload_completion = &c;
780 
781 		spin_unlock(&de->pde_unload_lock);
782 
783 		wait_for_completion(de->pde_unload_completion);
784 
785 		goto continue_removing;
786 	}
787 	spin_unlock(&de->pde_unload_lock);
788 
789 continue_removing:
790 	spin_lock(&de->pde_unload_lock);
791 	while (!list_empty(&de->pde_openers)) {
792 		struct pde_opener *pdeo;
793 
794 		pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
795 		list_del(&pdeo->lh);
796 		spin_unlock(&de->pde_unload_lock);
797 		pdeo->release(pdeo->inode, pdeo->file);
798 		kfree(pdeo);
799 		spin_lock(&de->pde_unload_lock);
800 	}
801 	spin_unlock(&de->pde_unload_lock);
802 
803 	if (S_ISDIR(de->mode))
804 		parent->nlink--;
805 	de->nlink = 0;
806 	WARN(de->subdir, KERN_WARNING "%s: removing non-empty directory "
807 			"'%s/%s', leaking at least '%s'\n", __func__,
808 			de->parent->name, de->name, de->subdir->name);
809 	if (atomic_dec_and_test(&de->count))
810 		free_proc_entry(de);
811 }
812