3abb1d90f5
kernfs_path*() functions always return the length of the full path but the path content is undefined if the length is larger than the provided buffer. This makes its behavior different from strlcpy() and requires error handling in all its users even when they don't care about truncation. In addition, the implementation can actully be simplified by making it behave properly in strlcpy() style. * Update kernfs_path_from_node_locked() to always fill up the buffer with path. If the buffer is not large enough, the output is truncated and terminated. * kernfs_path() no longer needs error handling. Make it a simple inline wrapper around kernfs_path_from_node(). * sysfs_warn_dup()'s use of kernfs_path() doesn't need error handling. Updated accordingly. * cgroup_path()'s use of kernfs_path() updated to retain the old behavior. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
158 lines
4 KiB
C
158 lines
4 KiB
C
/*
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* fs/sysfs/dir.c - sysfs core and dir operation implementation
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*
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* Copyright (c) 2001-3 Patrick Mochel
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
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*
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* This file is released under the GPLv2.
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#undef DEBUG
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#include <linux/fs.h>
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#include <linux/kobject.h>
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#include <linux/slab.h>
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#include "sysfs.h"
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DEFINE_SPINLOCK(sysfs_symlink_target_lock);
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void sysfs_warn_dup(struct kernfs_node *parent, const char *name)
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{
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char *buf;
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buf = kzalloc(PATH_MAX, GFP_KERNEL);
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if (buf)
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kernfs_path(parent, buf, PATH_MAX);
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WARN(1, KERN_WARNING "sysfs: cannot create duplicate filename '%s/%s'\n",
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buf, name);
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kfree(buf);
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}
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/**
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* sysfs_create_dir_ns - create a directory for an object with a namespace tag
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* @kobj: object we're creating directory for
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* @ns: the namespace tag to use
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*/
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int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
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{
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struct kernfs_node *parent, *kn;
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BUG_ON(!kobj);
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if (kobj->parent)
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parent = kobj->parent->sd;
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else
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parent = sysfs_root_kn;
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if (!parent)
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return -ENOENT;
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kn = kernfs_create_dir_ns(parent, kobject_name(kobj),
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S_IRWXU | S_IRUGO | S_IXUGO, kobj, ns);
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if (IS_ERR(kn)) {
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if (PTR_ERR(kn) == -EEXIST)
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sysfs_warn_dup(parent, kobject_name(kobj));
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return PTR_ERR(kn);
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}
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kobj->sd = kn;
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return 0;
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}
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/**
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* sysfs_remove_dir - remove an object's directory.
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* @kobj: object.
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*
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* The only thing special about this is that we remove any files in
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* the directory before we remove the directory, and we've inlined
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* what used to be sysfs_rmdir() below, instead of calling separately.
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*/
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void sysfs_remove_dir(struct kobject *kobj)
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{
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struct kernfs_node *kn = kobj->sd;
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/*
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* In general, kboject owner is responsible for ensuring removal
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* doesn't race with other operations and sysfs doesn't provide any
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* protection; however, when @kobj is used as a symlink target, the
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* symlinking entity usually doesn't own @kobj and thus has no
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* control over removal. @kobj->sd may be removed anytime
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* and symlink code may end up dereferencing an already freed node.
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*
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* sysfs_symlink_target_lock synchronizes @kobj->sd
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* disassociation against symlink operations so that symlink code
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* can safely dereference @kobj->sd.
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*/
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spin_lock(&sysfs_symlink_target_lock);
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kobj->sd = NULL;
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spin_unlock(&sysfs_symlink_target_lock);
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if (kn) {
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WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
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kernfs_remove(kn);
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}
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}
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int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
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const void *new_ns)
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{
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struct kernfs_node *parent;
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int ret;
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parent = kernfs_get_parent(kobj->sd);
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ret = kernfs_rename_ns(kobj->sd, parent, new_name, new_ns);
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kernfs_put(parent);
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return ret;
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}
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int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
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const void *new_ns)
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{
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struct kernfs_node *kn = kobj->sd;
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struct kernfs_node *new_parent;
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new_parent = new_parent_kobj && new_parent_kobj->sd ?
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new_parent_kobj->sd : sysfs_root_kn;
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return kernfs_rename_ns(kn, new_parent, kn->name, new_ns);
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}
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/**
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* sysfs_create_mount_point - create an always empty directory
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* @parent_kobj: kobject that will contain this always empty directory
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* @name: The name of the always empty directory to add
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*/
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int sysfs_create_mount_point(struct kobject *parent_kobj, const char *name)
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{
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struct kernfs_node *kn, *parent = parent_kobj->sd;
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kn = kernfs_create_empty_dir(parent, name);
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if (IS_ERR(kn)) {
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if (PTR_ERR(kn) == -EEXIST)
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sysfs_warn_dup(parent, name);
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return PTR_ERR(kn);
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(sysfs_create_mount_point);
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/**
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* sysfs_remove_mount_point - remove an always empty directory.
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* @parent_kobj: kobject that will contain this always empty directory
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* @name: The name of the always empty directory to remove
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*
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*/
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void sysfs_remove_mount_point(struct kobject *parent_kobj, const char *name)
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{
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struct kernfs_node *parent = parent_kobj->sd;
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kernfs_remove_by_name_ns(parent, name, NULL);
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}
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EXPORT_SYMBOL_GPL(sysfs_remove_mount_point);
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