2005-04-16 16:20:36 -06:00
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/*
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* symlink.c - operations for sysfs symlinks.
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*/
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#include <linux/fs.h>
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2002-04-09 13:14:34 -06:00
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#include <linux/mount.h>
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2005-04-16 16:20:36 -06:00
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#include <linux/module.h>
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#include <linux/kobject.h>
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#include <linux/namei.h>
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2006-12-20 02:52:44 -07:00
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#include <asm/semaphore.h>
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2005-04-16 16:20:36 -06:00
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#include "sysfs.h"
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2007-06-13 12:45:15 -06:00
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static int object_depth(struct sysfs_dirent *sd)
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2005-04-16 16:20:36 -06:00
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{
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int depth = 0;
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2007-06-13 12:45:15 -06:00
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for (; sd->s_parent; sd = sd->s_parent)
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depth++;
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2005-04-16 16:20:36 -06:00
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return depth;
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}
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2007-06-13 12:45:15 -06:00
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static int object_path_length(struct sysfs_dirent * sd)
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2005-04-16 16:20:36 -06:00
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{
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int length = 1;
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2007-06-13 12:45:15 -06:00
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for (; sd->s_parent; sd = sd->s_parent)
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length += strlen(sd->s_name) + 1;
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2005-04-16 16:20:36 -06:00
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return length;
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}
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2007-06-13 12:45:15 -06:00
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static void fill_object_path(struct sysfs_dirent *sd, char *buffer, int length)
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2005-04-16 16:20:36 -06:00
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{
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--length;
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2007-06-13 12:45:15 -06:00
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for (; sd->s_parent; sd = sd->s_parent) {
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int cur = strlen(sd->s_name);
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2005-04-16 16:20:36 -06:00
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/* back up enough to print this bus id with '/' */
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length -= cur;
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2007-06-13 12:45:15 -06:00
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strncpy(buffer + length, sd->s_name, cur);
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2005-04-16 16:20:36 -06:00
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*(buffer + --length) = '/';
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}
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}
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/**
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* sysfs_create_link - create symlink between two objects.
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* @kobj: object whose directory we're creating the link in.
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* @target: object we're pointing to.
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* @name: name of the symlink.
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*/
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2005-04-26 01:31:08 -06:00
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int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char * name)
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2005-04-16 16:20:36 -06:00
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{
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2007-06-13 12:45:15 -06:00
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struct sysfs_dirent *parent_sd = NULL;
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struct sysfs_dirent *target_sd = NULL;
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2007-06-13 13:27:23 -06:00
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struct sysfs_dirent *sd = NULL;
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2007-06-13 13:27:24 -06:00
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struct sysfs_addrm_cxt acxt;
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2007-06-13 13:27:23 -06:00
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int error;
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2005-04-16 16:20:36 -06:00
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2002-04-09 13:14:34 -06:00
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BUG_ON(!name);
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if (!kobj) {
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if (sysfs_mount && sysfs_mount->mnt_sb)
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2007-06-13 13:27:22 -06:00
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parent_sd = sysfs_mount->mnt_sb->s_root->d_fsdata;
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2002-04-09 13:14:34 -06:00
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} else
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2007-06-13 13:27:22 -06:00
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parent_sd = kobj->sd;
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2002-04-09 13:14:34 -06:00
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2007-06-13 13:27:23 -06:00
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error = -EFAULT;
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2007-06-13 13:27:22 -06:00
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if (!parent_sd)
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2007-06-13 13:27:23 -06:00
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goto out_put;
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2007-06-13 12:45:15 -06:00
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2007-06-13 13:27:22 -06:00
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/* target->sd can go away beneath us but is protected with
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2007-06-13 13:27:23 -06:00
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* sysfs_assoc_lock. Fetch target_sd from it.
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2007-06-13 12:45:15 -06:00
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*/
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2007-06-13 13:27:23 -06:00
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spin_lock(&sysfs_assoc_lock);
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2007-06-13 13:27:22 -06:00
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if (target->sd)
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target_sd = sysfs_get(target->sd);
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2007-06-13 13:27:23 -06:00
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spin_unlock(&sysfs_assoc_lock);
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2007-06-13 12:45:15 -06:00
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2007-06-13 13:27:23 -06:00
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error = -ENOENT;
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2007-06-13 12:45:15 -06:00
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if (!target_sd)
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2007-06-13 13:27:23 -06:00
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goto out_put;
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error = -ENOMEM;
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sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
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if (!sd)
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goto out_put;
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2007-07-18 01:14:45 -06:00
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2007-06-13 13:27:23 -06:00
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sd->s_elem.symlink.target_sd = target_sd;
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2007-07-18 01:14:45 -06:00
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target_sd = NULL; /* reference is now owned by the symlink */
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2005-04-16 16:20:36 -06:00
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2007-06-13 13:27:24 -06:00
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sysfs_addrm_start(&acxt, parent_sd);
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2007-06-13 12:45:15 -06:00
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2007-06-13 13:27:24 -06:00
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if (!sysfs_find_dirent(parent_sd, name)) {
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sysfs_add_one(&acxt, sd);
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sysfs_link_sibling(sd);
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}
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2007-06-13 12:45:15 -06:00
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2007-06-13 13:27:24 -06:00
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if (sysfs_addrm_finish(&acxt))
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return 0;
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error = -EEXIST;
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/* fall through */
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2007-06-13 13:27:23 -06:00
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out_put:
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sysfs_put(target_sd);
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sysfs_put(sd);
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2005-04-16 16:20:36 -06:00
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return error;
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}
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/**
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* sysfs_remove_link - remove symlink in object's directory.
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* @kobj: object we're acting for.
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* @name: name of the symlink to remove.
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*/
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2005-04-26 01:31:08 -06:00
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void sysfs_remove_link(struct kobject * kobj, const char * name)
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2005-04-16 16:20:36 -06:00
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{
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2007-06-13 13:27:22 -06:00
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sysfs_hash_and_remove(kobj->sd, name);
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2005-04-16 16:20:36 -06:00
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}
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2007-06-13 12:45:15 -06:00
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static int sysfs_get_target_path(struct sysfs_dirent * parent_sd,
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struct sysfs_dirent * target_sd, char *path)
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2005-04-16 16:20:36 -06:00
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{
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char * s;
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int depth, size;
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2007-06-13 12:45:15 -06:00
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depth = object_depth(parent_sd);
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size = object_path_length(target_sd) + depth * 3 - 1;
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2005-04-16 16:20:36 -06:00
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if (size > PATH_MAX)
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return -ENAMETOOLONG;
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pr_debug("%s: depth = %d, size = %d\n", __FUNCTION__, depth, size);
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for (s = path; depth--; s += 3)
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strcpy(s,"../");
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2007-06-13 12:45:15 -06:00
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fill_object_path(target_sd, path, size);
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2005-04-16 16:20:36 -06:00
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pr_debug("%s: path = '%s'\n", __FUNCTION__, path);
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return 0;
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}
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static int sysfs_getlink(struct dentry *dentry, char * path)
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{
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2007-06-13 12:45:15 -06:00
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struct sysfs_dirent *sd = dentry->d_fsdata;
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struct sysfs_dirent *parent_sd = sd->s_parent;
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struct sysfs_dirent *target_sd = sd->s_elem.symlink.target_sd;
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int error;
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2005-04-16 16:20:36 -06:00
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2007-06-13 13:27:23 -06:00
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mutex_lock(&sysfs_mutex);
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2007-06-13 12:45:15 -06:00
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error = sysfs_get_target_path(parent_sd, target_sd, path);
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2007-06-13 13:27:23 -06:00
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mutex_unlock(&sysfs_mutex);
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2005-04-16 16:20:36 -06:00
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2007-06-13 12:45:15 -06:00
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return error;
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2005-04-16 16:20:36 -06:00
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}
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2005-08-19 19:02:56 -06:00
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static void *sysfs_follow_link(struct dentry *dentry, struct nameidata *nd)
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2005-04-16 16:20:36 -06:00
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{
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int error = -ENOMEM;
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unsigned long page = get_zeroed_page(GFP_KERNEL);
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if (page)
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error = sysfs_getlink(dentry, (char *) page);
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nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
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2005-08-19 19:02:56 -06:00
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return NULL;
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2005-04-16 16:20:36 -06:00
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}
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2005-08-19 19:02:56 -06:00
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static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
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2005-04-16 16:20:36 -06:00
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{
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char *page = nd_get_link(nd);
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if (!IS_ERR(page))
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free_page((unsigned long)page);
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}
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2007-02-12 01:55:40 -07:00
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const struct inode_operations sysfs_symlink_inode_operations = {
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2005-04-16 16:20:36 -06:00
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.readlink = generic_readlink,
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.follow_link = sysfs_follow_link,
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.put_link = sysfs_put_link,
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};
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EXPORT_SYMBOL_GPL(sysfs_create_link);
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EXPORT_SYMBOL_GPL(sysfs_remove_link);
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