2 * proc/fs/generic.c --- generic routines for the proc-fs
4 * This file contains generic proc-fs routines for handling
5 * directories and files.
7 * Copyright (C) 1991, 1992 Linus Torvalds.
8 * Copyright (C) 1997 Theodore Ts'o
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/init.h>
18 #include <linux/idr.h>
19 #include <linux/namei.h>
20 #include <linux/bitops.h>
21 #include <linux/spinlock.h>
22 #include <linux/completion.h>
23 #include <asm/uaccess.h>
27 DEFINE_SPINLOCK(proc_subdir_lock);
29 static int proc_match(int len, const char *name, struct proc_dir_entry *de)
31 if (de->namelen != len)
33 return !memcmp(name, de->name, len);
36 /* buffer size is one page but our output routines use some slack for overruns */
37 #define PROC_BLOCK_SIZE (PAGE_SIZE - 1024)
40 proc_file_read(struct file *file, char __user *buf, size_t nbytes,
43 struct inode * inode = file->f_path.dentry->d_inode;
49 struct proc_dir_entry * dp;
50 unsigned long long pos;
53 * Gaah, please just use "seq_file" instead. The legacy /proc
54 * interfaces cut loff_t down to off_t for reads, and ignore
55 * the offset entirely for writes..
58 if (pos > MAX_NON_LFS)
60 if (nbytes > MAX_NON_LFS - pos)
61 nbytes = MAX_NON_LFS - pos;
64 if (!(page = (char*) __get_free_page(GFP_TEMPORARY)))
67 while ((nbytes > 0) && !eof) {
68 count = min_t(size_t, PROC_BLOCK_SIZE, nbytes);
73 * How to be a proc read function
74 * ------------------------------
76 * int f(char *buffer, char **start, off_t offset,
77 * int count, int *peof, void *dat)
79 * Assume that the buffer is "count" bytes in size.
81 * If you know you have supplied all the data you
84 * You have three ways to return data:
85 * 0) Leave *start = NULL. (This is the default.)
86 * Put the data of the requested offset at that
87 * offset within the buffer. Return the number (n)
88 * of bytes there are from the beginning of the
89 * buffer up to the last byte of data. If the
90 * number of supplied bytes (= n - offset) is
91 * greater than zero and you didn't signal eof
92 * and the reader is prepared to take more data
93 * you will be called again with the requested
94 * offset advanced by the number of bytes
95 * absorbed. This interface is useful for files
96 * no larger than the buffer.
97 * 1) Set *start = an unsigned long value less than
98 * the buffer address but greater than zero.
99 * Put the data of the requested offset at the
100 * beginning of the buffer. Return the number of
101 * bytes of data placed there. If this number is
102 * greater than zero and you didn't signal eof
103 * and the reader is prepared to take more data
104 * you will be called again with the requested
105 * offset advanced by *start. This interface is
106 * useful when you have a large file consisting
107 * of a series of blocks which you want to count
108 * and return as wholes.
109 * (Hack by Paul.Russell@rustcorp.com.au)
110 * 2) Set *start = an address within the buffer.
111 * Put the data of the requested offset at *start.
112 * Return the number of bytes of data placed there.
113 * If this number is greater than zero and you
114 * didn't signal eof and the reader is prepared to
115 * take more data you will be called again with the
116 * requested offset advanced by the number of bytes
119 n = dp->read_proc(page, &start, *ppos,
120 count, &eof, dp->data);
124 if (n == 0) /* end of file */
126 if (n < 0) { /* error */
135 "proc_file_read: Apparent buffer overflow!\n");
143 start = page + *ppos;
144 } else if (start < page) {
147 "proc_file_read: Apparent buffer overflow!\n");
152 * Don't reduce n because doing so might
153 * cut off part of a data block.
156 "proc_file_read: Read count exceeded\n");
158 } else /* start >= page */ {
159 unsigned long startoff = (unsigned long)(start - page);
160 if (n > (PAGE_SIZE - startoff)) {
162 "proc_file_read: Apparent buffer overflow!\n");
163 n = PAGE_SIZE - startoff;
169 n -= copy_to_user(buf, start < page ? page : start, n);
176 *ppos += start < page ? (unsigned long)start : n;
181 free_page((unsigned long) page);
186 proc_file_write(struct file *file, const char __user *buffer,
187 size_t count, loff_t *ppos)
189 struct inode *inode = file->f_path.dentry->d_inode;
190 struct proc_dir_entry * dp;
197 /* FIXME: does this routine need ppos? probably... */
198 return dp->write_proc(file, buffer, count, dp->data);
203 proc_file_lseek(struct file *file, loff_t offset, int orig)
205 loff_t retval = -EINVAL;
208 offset += file->f_pos;
211 if (offset < 0 || offset > MAX_NON_LFS)
213 file->f_pos = retval = offset;
218 static const struct file_operations proc_file_operations = {
219 .llseek = proc_file_lseek,
220 .read = proc_file_read,
221 .write = proc_file_write,
224 static int proc_notify_change(struct dentry *dentry, struct iattr *iattr)
226 struct inode *inode = dentry->d_inode;
227 struct proc_dir_entry *de = PDE(inode);
230 error = inode_change_ok(inode, iattr);
234 error = inode_setattr(inode, iattr);
238 de->uid = inode->i_uid;
239 de->gid = inode->i_gid;
240 de->mode = inode->i_mode;
245 static int proc_getattr(struct vfsmount *mnt, struct dentry *dentry,
248 struct inode *inode = dentry->d_inode;
249 struct proc_dir_entry *de = PROC_I(inode)->pde;
251 inode->i_nlink = de->nlink;
253 generic_fillattr(inode, stat);
257 static const struct inode_operations proc_file_inode_operations = {
258 .setattr = proc_notify_change,
262 * This function parses a name such as "tty/driver/serial", and
263 * returns the struct proc_dir_entry for "/proc/tty/driver", and
264 * returns "serial" in residual.
266 static int xlate_proc_name(const char *name,
267 struct proc_dir_entry **ret, const char **residual)
269 const char *cp = name, *next;
270 struct proc_dir_entry *de;
278 spin_lock(&proc_subdir_lock);
280 next = strchr(cp, '/');
285 for (de = de->subdir; de ; de = de->next) {
286 if (proc_match(len, cp, de))
298 spin_unlock(&proc_subdir_lock);
302 static DEFINE_IDA(proc_inum_ida);
303 static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
305 #define PROC_DYNAMIC_FIRST 0xF0000000U
308 * Return an inode number between PROC_DYNAMIC_FIRST and
309 * 0xffffffff, or zero on failure.
311 * Current inode allocations in the proc-fs (hex-numbers):
314 * 00000001-00000fff static entries (goners)
317 * 00001000-00001fff unused
318 * 0001xxxx-7fffxxxx pid-dir entries for pid 1-7fff
319 * 80000000-efffffff unused
320 * f0000000-ffffffff dynamic entries
323 * Once we split the thing into several virtual filesystems,
324 * we will get rid of magical ranges (and this comment, BTW).
326 static unsigned int get_inode_number(void)
332 if (ida_pre_get(&proc_inum_ida, GFP_KERNEL) == 0)
335 spin_lock(&proc_inum_lock);
336 error = ida_get_new(&proc_inum_ida, &i);
337 spin_unlock(&proc_inum_lock);
338 if (error == -EAGAIN)
343 if (i > UINT_MAX - PROC_DYNAMIC_FIRST) {
344 spin_lock(&proc_inum_lock);
345 ida_remove(&proc_inum_ida, i);
346 spin_unlock(&proc_inum_lock);
349 return PROC_DYNAMIC_FIRST + i;
352 static void release_inode_number(unsigned int inum)
354 spin_lock(&proc_inum_lock);
355 ida_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
356 spin_unlock(&proc_inum_lock);
359 static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
361 nd_set_link(nd, PDE(dentry->d_inode)->data);
365 static const struct inode_operations proc_link_inode_operations = {
366 .readlink = generic_readlink,
367 .follow_link = proc_follow_link,
371 * As some entries in /proc are volatile, we want to
372 * get rid of unused dentries. This could be made
373 * smarter: we could keep a "volatile" flag in the
374 * inode to indicate which ones to keep.
376 static int proc_delete_dentry(struct dentry * dentry)
381 static const struct dentry_operations proc_dentry_operations =
383 .d_delete = proc_delete_dentry,
387 * Don't create negative dentries here, return -ENOENT by hand
390 struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir,
391 struct dentry *dentry)
393 struct inode *inode = NULL;
396 spin_lock(&proc_subdir_lock);
397 for (de = de->subdir; de ; de = de->next) {
398 if (de->namelen != dentry->d_name.len)
400 if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
405 spin_unlock(&proc_subdir_lock);
407 inode = proc_get_inode(dir->i_sb, ino, de);
411 spin_unlock(&proc_subdir_lock);
415 dentry->d_op = &proc_dentry_operations;
416 d_add(dentry, inode);
421 return ERR_PTR(error);
424 struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry,
425 struct nameidata *nd)
427 return proc_lookup_de(PDE(dir), dir, dentry);
431 * This returns non-zero if at EOF, so that the /proc
432 * root directory can use this and check if it should
433 * continue with the <pid> entries..
435 * Note that the VFS-layer doesn't care about the return
436 * value of the readdir() call, as long as it's non-negative
439 int proc_readdir_de(struct proc_dir_entry *de, struct file *filp, void *dirent,
444 struct inode *inode = filp->f_path.dentry->d_inode;
451 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
457 if (filldir(dirent, "..", 2, i,
458 parent_ino(filp->f_path.dentry),
465 spin_lock(&proc_subdir_lock);
471 spin_unlock(&proc_subdir_lock);
481 struct proc_dir_entry *next;
483 /* filldir passes info to user space */
485 spin_unlock(&proc_subdir_lock);
486 if (filldir(dirent, de->name, de->namelen, filp->f_pos,
487 de->low_ino, de->mode >> 12) < 0) {
491 spin_lock(&proc_subdir_lock);
497 spin_unlock(&proc_subdir_lock);
504 int proc_readdir(struct file *filp, void *dirent, filldir_t filldir)
506 struct inode *inode = filp->f_path.dentry->d_inode;
508 return proc_readdir_de(PDE(inode), filp, dirent, filldir);
512 * These are the generic /proc directory operations. They
513 * use the in-memory "struct proc_dir_entry" tree to parse
514 * the /proc directory.
516 static const struct file_operations proc_dir_operations = {
517 .llseek = generic_file_llseek,
518 .read = generic_read_dir,
519 .readdir = proc_readdir,
523 * proc directories can do almost nothing..
525 static const struct inode_operations proc_dir_inode_operations = {
526 .lookup = proc_lookup,
527 .getattr = proc_getattr,
528 .setattr = proc_notify_change,
531 static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp)
534 struct proc_dir_entry *tmp;
536 i = get_inode_number();
541 if (S_ISDIR(dp->mode)) {
542 if (dp->proc_iops == NULL) {
543 dp->proc_fops = &proc_dir_operations;
544 dp->proc_iops = &proc_dir_inode_operations;
547 } else if (S_ISLNK(dp->mode)) {
548 if (dp->proc_iops == NULL)
549 dp->proc_iops = &proc_link_inode_operations;
550 } else if (S_ISREG(dp->mode)) {
551 if (dp->proc_fops == NULL)
552 dp->proc_fops = &proc_file_operations;
553 if (dp->proc_iops == NULL)
554 dp->proc_iops = &proc_file_inode_operations;
557 spin_lock(&proc_subdir_lock);
559 for (tmp = dir->subdir; tmp; tmp = tmp->next)
560 if (strcmp(tmp->name, dp->name) == 0) {
561 WARN(1, KERN_WARNING "proc_dir_entry '%s/%s' already registered\n",
562 dir->name, dp->name);
566 dp->next = dir->subdir;
569 spin_unlock(&proc_subdir_lock);
574 static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
579 struct proc_dir_entry *ent = NULL;
580 const char *fn = name;
583 /* make sure name is valid */
584 if (!name || !strlen(name)) goto out;
586 if (xlate_proc_name(name, parent, &fn) != 0)
589 /* At this point there must not be any '/' characters beyond *fn */
595 ent = kmalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL);
598 memset(ent, 0, sizeof(struct proc_dir_entry));
599 memcpy(((char *) ent) + sizeof(struct proc_dir_entry), fn, len + 1);
600 ent->name = ((char *) ent) + sizeof(*ent);
604 atomic_set(&ent->count, 1);
606 spin_lock_init(&ent->pde_unload_lock);
607 ent->pde_unload_completion = NULL;
608 INIT_LIST_HEAD(&ent->pde_openers);
613 struct proc_dir_entry *proc_symlink(const char *name,
614 struct proc_dir_entry *parent, const char *dest)
616 struct proc_dir_entry *ent;
618 ent = __proc_create(&parent, name,
619 (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);
622 ent->data = kmalloc((ent->size=strlen(dest))+1, GFP_KERNEL);
624 strcpy((char*)ent->data,dest);
625 if (proc_register(parent, ent) < 0) {
638 struct proc_dir_entry *proc_mkdir_mode(const char *name, mode_t mode,
639 struct proc_dir_entry *parent)
641 struct proc_dir_entry *ent;
643 ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
645 if (proc_register(parent, ent) < 0) {
653 struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name,
654 struct proc_dir_entry *parent)
656 struct proc_dir_entry *ent;
658 ent = __proc_create(&parent, name, S_IFDIR | S_IRUGO | S_IXUGO, 2);
661 if (proc_register(parent, ent) < 0) {
668 EXPORT_SYMBOL_GPL(proc_net_mkdir);
670 struct proc_dir_entry *proc_mkdir(const char *name,
671 struct proc_dir_entry *parent)
673 return proc_mkdir_mode(name, S_IRUGO | S_IXUGO, parent);
676 struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode,
677 struct proc_dir_entry *parent)
679 struct proc_dir_entry *ent;
683 if ((mode & S_IALLUGO) == 0)
684 mode |= S_IRUGO | S_IXUGO;
687 if ((mode & S_IFMT) == 0)
689 if ((mode & S_IALLUGO) == 0)
694 ent = __proc_create(&parent, name, mode, nlink);
696 if (proc_register(parent, ent) < 0) {
704 struct proc_dir_entry *proc_create_data(const char *name, mode_t mode,
705 struct proc_dir_entry *parent,
706 const struct file_operations *proc_fops,
709 struct proc_dir_entry *pde;
713 if ((mode & S_IALLUGO) == 0)
714 mode |= S_IRUGO | S_IXUGO;
717 if ((mode & S_IFMT) == 0)
719 if ((mode & S_IALLUGO) == 0)
724 pde = __proc_create(&parent, name, mode, nlink);
727 pde->proc_fops = proc_fops;
729 if (proc_register(parent, pde) < 0)
738 void free_proc_entry(struct proc_dir_entry *de)
740 unsigned int ino = de->low_ino;
742 if (ino < PROC_DYNAMIC_FIRST)
745 release_inode_number(ino);
747 if (S_ISLNK(de->mode))
753 * Remove a /proc entry and free it if it's not currently in use.
755 void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
757 struct proc_dir_entry **p;
758 struct proc_dir_entry *de = NULL;
759 const char *fn = name;
762 if (xlate_proc_name(name, &parent, &fn) != 0)
766 spin_lock(&proc_subdir_lock);
767 for (p = &parent->subdir; *p; p=&(*p)->next ) {
768 if (proc_match(len, fn, *p)) {
775 spin_unlock(&proc_subdir_lock);
779 spin_lock(&de->pde_unload_lock);
781 * Stop accepting new callers into module. If you're
782 * dynamically allocating ->proc_fops, save a pointer somewhere.
784 de->proc_fops = NULL;
785 /* Wait until all existing callers into module are done. */
786 if (de->pde_users > 0) {
787 DECLARE_COMPLETION_ONSTACK(c);
789 if (!de->pde_unload_completion)
790 de->pde_unload_completion = &c;
792 spin_unlock(&de->pde_unload_lock);
794 wait_for_completion(de->pde_unload_completion);
796 goto continue_removing;
798 spin_unlock(&de->pde_unload_lock);
801 spin_lock(&de->pde_unload_lock);
802 while (!list_empty(&de->pde_openers)) {
803 struct pde_opener *pdeo;
805 pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
807 spin_unlock(&de->pde_unload_lock);
808 pdeo->release(pdeo->inode, pdeo->file);
810 spin_lock(&de->pde_unload_lock);
812 spin_unlock(&de->pde_unload_lock);
814 if (S_ISDIR(de->mode))
817 WARN(de->subdir, KERN_WARNING "%s: removing non-empty directory "
818 "'%s/%s', leaking at least '%s'\n", __func__,
819 de->parent->name, de->name, de->subdir->name);
820 if (atomic_dec_and_test(&de->count))