android_kernel_motorola_sm6225/fs/sysfs/dir.c
Eric W. Biederman 846f99749a sysfs: Add lockdep annotations for the sysfs active reference
Holding locks over device_del -> kobject_del -> sysfs_deactivate can
cause deadlocks if those same locks are grabbed in sysfs show or store
methods.

The I model s_active count + completion as a sleeping read/write lock.
I describe to lockdep sysfs_get_active as a read_trylock,
sysfs_put_active as a read_unlock, and sysfs_deactivate as a
write_lock and write_unlock pair.  This seems to capture the essence
for purposes of finding deadlocks, and in my testing gives finds real
issues and ignores non-issues.

This brings us back to holding locks over kobject_del is a problem
that ideally we should find a way of addressing, but at least lockdep
can tell us about the problems instead of requiring developers to debug
rare strange system deadlocks, that happen when sysfs files are removed
while being written to.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-01-04 12:34:46 -08:00

892 lines
20 KiB
C

/*
* fs/sysfs/dir.c - sysfs core and dir operation implementation
*
* Copyright (c) 2001-3 Patrick Mochel
* Copyright (c) 2007 SUSE Linux Products GmbH
* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
*
* This file is released under the GPLv2.
*
* Please see Documentation/filesystems/sysfs.txt for more information.
*/
#undef DEBUG
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/module.h>
#include <linux/kobject.h>
#include <linux/namei.h>
#include <linux/idr.h>
#include <linux/completion.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/security.h>
#include "sysfs.h"
DEFINE_MUTEX(sysfs_mutex);
DEFINE_SPINLOCK(sysfs_assoc_lock);
static DEFINE_SPINLOCK(sysfs_ino_lock);
static DEFINE_IDA(sysfs_ino_ida);
/**
* sysfs_link_sibling - link sysfs_dirent into sibling list
* @sd: sysfs_dirent of interest
*
* Link @sd into its sibling list which starts from
* sd->s_parent->s_dir.children.
*
* Locking:
* mutex_lock(sysfs_mutex)
*/
static void sysfs_link_sibling(struct sysfs_dirent *sd)
{
struct sysfs_dirent *parent_sd = sd->s_parent;
struct sysfs_dirent **pos;
BUG_ON(sd->s_sibling);
/* Store directory entries in order by ino. This allows
* readdir to properly restart without having to add a
* cursor into the s_dir.children list.
*/
for (pos = &parent_sd->s_dir.children; *pos; pos = &(*pos)->s_sibling) {
if (sd->s_ino < (*pos)->s_ino)
break;
}
sd->s_sibling = *pos;
*pos = sd;
}
/**
* sysfs_unlink_sibling - unlink sysfs_dirent from sibling list
* @sd: sysfs_dirent of interest
*
* Unlink @sd from its sibling list which starts from
* sd->s_parent->s_dir.children.
*
* Locking:
* mutex_lock(sysfs_mutex)
*/
static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
{
struct sysfs_dirent **pos;
for (pos = &sd->s_parent->s_dir.children; *pos;
pos = &(*pos)->s_sibling) {
if (*pos == sd) {
*pos = sd->s_sibling;
sd->s_sibling = NULL;
break;
}
}
}
/**
* sysfs_get_active - get an active reference to sysfs_dirent
* @sd: sysfs_dirent to get an active reference to
*
* Get an active reference of @sd. This function is noop if @sd
* is NULL.
*
* RETURNS:
* Pointer to @sd on success, NULL on failure.
*/
static struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
{
if (unlikely(!sd))
return NULL;
while (1) {
int v, t;
v = atomic_read(&sd->s_active);
if (unlikely(v < 0))
return NULL;
t = atomic_cmpxchg(&sd->s_active, v, v + 1);
if (likely(t == v)) {
rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
return sd;
}
if (t < 0)
return NULL;
cpu_relax();
}
}
/**
* sysfs_put_active - put an active reference to sysfs_dirent
* @sd: sysfs_dirent to put an active reference to
*
* Put an active reference to @sd. This function is noop if @sd
* is NULL.
*/
static void sysfs_put_active(struct sysfs_dirent *sd)
{
struct completion *cmpl;
int v;
if (unlikely(!sd))
return;
rwsem_release(&sd->dep_map, 1, _RET_IP_);
v = atomic_dec_return(&sd->s_active);
if (likely(v != SD_DEACTIVATED_BIAS))
return;
/* atomic_dec_return() is a mb(), we'll always see the updated
* sd->s_sibling.
*/
cmpl = (void *)sd->s_sibling;
complete(cmpl);
}
/**
* sysfs_get_active_two - get active references to sysfs_dirent and parent
* @sd: sysfs_dirent of interest
*
* Get active reference to @sd and its parent. Parent's active
* reference is grabbed first. This function is noop if @sd is
* NULL.
*
* RETURNS:
* Pointer to @sd on success, NULL on failure.
*/
struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd)
{
if (sd) {
if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent)))
return NULL;
if (unlikely(!sysfs_get_active(sd))) {
sysfs_put_active(sd->s_parent);
return NULL;
}
}
return sd;
}
/**
* sysfs_put_active_two - put active references to sysfs_dirent and parent
* @sd: sysfs_dirent of interest
*
* Put active references to @sd and its parent. This function is
* noop if @sd is NULL.
*/
void sysfs_put_active_two(struct sysfs_dirent *sd)
{
if (sd) {
sysfs_put_active(sd);
sysfs_put_active(sd->s_parent);
}
}
/**
* sysfs_deactivate - deactivate sysfs_dirent
* @sd: sysfs_dirent to deactivate
*
* Deny new active references and drain existing ones.
*/
static void sysfs_deactivate(struct sysfs_dirent *sd)
{
DECLARE_COMPLETION_ONSTACK(wait);
int v;
BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED));
sd->s_sibling = (void *)&wait;
rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_);
/* atomic_add_return() is a mb(), put_active() will always see
* the updated sd->s_sibling.
*/
v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
if (v != SD_DEACTIVATED_BIAS) {
lock_contended(&sd->dep_map, _RET_IP_);
wait_for_completion(&wait);
}
sd->s_sibling = NULL;
lock_acquired(&sd->dep_map, _RET_IP_);
rwsem_release(&sd->dep_map, 1, _RET_IP_);
}
static int sysfs_alloc_ino(ino_t *pino)
{
int ino, rc;
retry:
spin_lock(&sysfs_ino_lock);
rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
spin_unlock(&sysfs_ino_lock);
if (rc == -EAGAIN) {
if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
goto retry;
rc = -ENOMEM;
}
*pino = ino;
return rc;
}
static void sysfs_free_ino(ino_t ino)
{
spin_lock(&sysfs_ino_lock);
ida_remove(&sysfs_ino_ida, ino);
spin_unlock(&sysfs_ino_lock);
}
void release_sysfs_dirent(struct sysfs_dirent * sd)
{
struct sysfs_dirent *parent_sd;
repeat:
/* Moving/renaming is always done while holding reference.
* sd->s_parent won't change beneath us.
*/
parent_sd = sd->s_parent;
if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
sysfs_put(sd->s_symlink.target_sd);
if (sysfs_type(sd) & SYSFS_COPY_NAME)
kfree(sd->s_name);
if (sd->s_iattr && sd->s_iattr->ia_secdata)
security_release_secctx(sd->s_iattr->ia_secdata,
sd->s_iattr->ia_secdata_len);
kfree(sd->s_iattr);
sysfs_free_ino(sd->s_ino);
kmem_cache_free(sysfs_dir_cachep, sd);
sd = parent_sd;
if (sd && atomic_dec_and_test(&sd->s_count))
goto repeat;
}
static int sysfs_dentry_delete(struct dentry *dentry)
{
struct sysfs_dirent *sd = dentry->d_fsdata;
return !!(sd->s_flags & SYSFS_FLAG_REMOVED);
}
static int sysfs_dentry_revalidate(struct dentry *dentry, struct nameidata *nd)
{
struct sysfs_dirent *sd = dentry->d_fsdata;
int is_dir;
mutex_lock(&sysfs_mutex);
/* The sysfs dirent has been deleted */
if (sd->s_flags & SYSFS_FLAG_REMOVED)
goto out_bad;
/* The sysfs dirent has been moved? */
if (dentry->d_parent->d_fsdata != sd->s_parent)
goto out_bad;
/* The sysfs dirent has been renamed */
if (strcmp(dentry->d_name.name, sd->s_name) != 0)
goto out_bad;
mutex_unlock(&sysfs_mutex);
out_valid:
return 1;
out_bad:
/* Remove the dentry from the dcache hashes.
* If this is a deleted dentry we use d_drop instead of d_delete
* so sysfs doesn't need to cope with negative dentries.
*
* If this is a dentry that has simply been renamed we
* use d_drop to remove it from the dcache lookup on its
* old parent. If this dentry persists later when a lookup
* is performed at its new name the dentry will be readded
* to the dcache hashes.
*/
is_dir = (sysfs_type(sd) == SYSFS_DIR);
mutex_unlock(&sysfs_mutex);
if (is_dir) {
/* If we have submounts we must allow the vfs caches
* to lie about the state of the filesystem to prevent
* leaks and other nasty things.
*/
if (have_submounts(dentry))
goto out_valid;
shrink_dcache_parent(dentry);
}
d_drop(dentry);
return 0;
}
static void sysfs_dentry_iput(struct dentry *dentry, struct inode *inode)
{
struct sysfs_dirent * sd = dentry->d_fsdata;
sysfs_put(sd);
iput(inode);
}
static const struct dentry_operations sysfs_dentry_ops = {
.d_revalidate = sysfs_dentry_revalidate,
.d_delete = sysfs_dentry_delete,
.d_iput = sysfs_dentry_iput,
};
struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
{
char *dup_name = NULL;
struct sysfs_dirent *sd;
if (type & SYSFS_COPY_NAME) {
name = dup_name = kstrdup(name, GFP_KERNEL);
if (!name)
return NULL;
}
sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
if (!sd)
goto err_out1;
if (sysfs_alloc_ino(&sd->s_ino))
goto err_out2;
atomic_set(&sd->s_count, 1);
atomic_set(&sd->s_active, 0);
sysfs_dirent_init_lockdep(sd);
sd->s_name = name;
sd->s_mode = mode;
sd->s_flags = type;
return sd;
err_out2:
kmem_cache_free(sysfs_dir_cachep, sd);
err_out1:
kfree(dup_name);
return NULL;
}
/**
* sysfs_addrm_start - prepare for sysfs_dirent add/remove
* @acxt: pointer to sysfs_addrm_cxt to be used
* @parent_sd: parent sysfs_dirent
*
* This function is called when the caller is about to add or
* remove sysfs_dirent under @parent_sd. This function acquires
* sysfs_mutex. @acxt is used to keep and pass context to
* other addrm functions.
*
* LOCKING:
* Kernel thread context (may sleep). sysfs_mutex is locked on
* return.
*/
void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
struct sysfs_dirent *parent_sd)
{
memset(acxt, 0, sizeof(*acxt));
acxt->parent_sd = parent_sd;
mutex_lock(&sysfs_mutex);
}
/**
* __sysfs_add_one - add sysfs_dirent to parent without warning
* @acxt: addrm context to use
* @sd: sysfs_dirent to be added
*
* Get @acxt->parent_sd and set sd->s_parent to it and increment
* nlink of parent inode if @sd is a directory and link into the
* children list of the parent.
*
* This function should be called between calls to
* sysfs_addrm_start() and sysfs_addrm_finish() and should be
* passed the same @acxt as passed to sysfs_addrm_start().
*
* LOCKING:
* Determined by sysfs_addrm_start().
*
* RETURNS:
* 0 on success, -EEXIST if entry with the given name already
* exists.
*/
int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
{
struct sysfs_inode_attrs *ps_iattr;
if (sysfs_find_dirent(acxt->parent_sd, sd->s_name))
return -EEXIST;
sd->s_parent = sysfs_get(acxt->parent_sd);
sysfs_link_sibling(sd);
/* Update timestamps on the parent */
ps_iattr = acxt->parent_sd->s_iattr;
if (ps_iattr) {
struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
}
return 0;
}
/**
* sysfs_pathname - return full path to sysfs dirent
* @sd: sysfs_dirent whose path we want
* @path: caller allocated buffer
*
* Gives the name "/" to the sysfs_root entry; any path returned
* is relative to wherever sysfs is mounted.
*
* XXX: does no error checking on @path size
*/
static char *sysfs_pathname(struct sysfs_dirent *sd, char *path)
{
if (sd->s_parent) {
sysfs_pathname(sd->s_parent, path);
strcat(path, "/");
}
strcat(path, sd->s_name);
return path;
}
/**
* sysfs_add_one - add sysfs_dirent to parent
* @acxt: addrm context to use
* @sd: sysfs_dirent to be added
*
* Get @acxt->parent_sd and set sd->s_parent to it and increment
* nlink of parent inode if @sd is a directory and link into the
* children list of the parent.
*
* This function should be called between calls to
* sysfs_addrm_start() and sysfs_addrm_finish() and should be
* passed the same @acxt as passed to sysfs_addrm_start().
*
* LOCKING:
* Determined by sysfs_addrm_start().
*
* RETURNS:
* 0 on success, -EEXIST if entry with the given name already
* exists.
*/
int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
{
int ret;
ret = __sysfs_add_one(acxt, sd);
if (ret == -EEXIST) {
char *path = kzalloc(PATH_MAX, GFP_KERNEL);
WARN(1, KERN_WARNING
"sysfs: cannot create duplicate filename '%s'\n",
(path == NULL) ? sd->s_name :
strcat(strcat(sysfs_pathname(acxt->parent_sd, path), "/"),
sd->s_name));
kfree(path);
}
return ret;
}
/**
* sysfs_remove_one - remove sysfs_dirent from parent
* @acxt: addrm context to use
* @sd: sysfs_dirent to be removed
*
* Mark @sd removed and drop nlink of parent inode if @sd is a
* directory. @sd is unlinked from the children list.
*
* This function should be called between calls to
* sysfs_addrm_start() and sysfs_addrm_finish() and should be
* passed the same @acxt as passed to sysfs_addrm_start().
*
* LOCKING:
* Determined by sysfs_addrm_start().
*/
void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
{
struct sysfs_inode_attrs *ps_iattr;
BUG_ON(sd->s_flags & SYSFS_FLAG_REMOVED);
sysfs_unlink_sibling(sd);
/* Update timestamps on the parent */
ps_iattr = acxt->parent_sd->s_iattr;
if (ps_iattr) {
struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
}
sd->s_flags |= SYSFS_FLAG_REMOVED;
sd->s_sibling = acxt->removed;
acxt->removed = sd;
}
/**
* sysfs_addrm_finish - finish up sysfs_dirent add/remove
* @acxt: addrm context to finish up
*
* Finish up sysfs_dirent add/remove. Resources acquired by
* sysfs_addrm_start() are released and removed sysfs_dirents are
* cleaned up.
*
* LOCKING:
* sysfs_mutex is released.
*/
void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
{
/* release resources acquired by sysfs_addrm_start() */
mutex_unlock(&sysfs_mutex);
/* kill removed sysfs_dirents */
while (acxt->removed) {
struct sysfs_dirent *sd = acxt->removed;
acxt->removed = sd->s_sibling;
sd->s_sibling = NULL;
sysfs_deactivate(sd);
unmap_bin_file(sd);
sysfs_put(sd);
}
}
/**
* sysfs_find_dirent - find sysfs_dirent with the given name
* @parent_sd: sysfs_dirent to search under
* @name: name to look for
*
* Look for sysfs_dirent with name @name under @parent_sd.
*
* LOCKING:
* mutex_lock(sysfs_mutex)
*
* RETURNS:
* Pointer to sysfs_dirent if found, NULL if not.
*/
struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
const unsigned char *name)
{
struct sysfs_dirent *sd;
for (sd = parent_sd->s_dir.children; sd; sd = sd->s_sibling)
if (!strcmp(sd->s_name, name))
return sd;
return NULL;
}
/**
* sysfs_get_dirent - find and get sysfs_dirent with the given name
* @parent_sd: sysfs_dirent to search under
* @name: name to look for
*
* Look for sysfs_dirent with name @name under @parent_sd and get
* it if found.
*
* LOCKING:
* Kernel thread context (may sleep). Grabs sysfs_mutex.
*
* RETURNS:
* Pointer to sysfs_dirent if found, NULL if not.
*/
struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
const unsigned char *name)
{
struct sysfs_dirent *sd;
mutex_lock(&sysfs_mutex);
sd = sysfs_find_dirent(parent_sd, name);
sysfs_get(sd);
mutex_unlock(&sysfs_mutex);
return sd;
}
EXPORT_SYMBOL_GPL(sysfs_get_dirent);
static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
const char *name, struct sysfs_dirent **p_sd)
{
umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
struct sysfs_addrm_cxt acxt;
struct sysfs_dirent *sd;
int rc;
/* allocate */
sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
if (!sd)
return -ENOMEM;
sd->s_dir.kobj = kobj;
/* link in */
sysfs_addrm_start(&acxt, parent_sd);
rc = sysfs_add_one(&acxt, sd);
sysfs_addrm_finish(&acxt);
if (rc == 0)
*p_sd = sd;
else
sysfs_put(sd);
return rc;
}
int sysfs_create_subdir(struct kobject *kobj, const char *name,
struct sysfs_dirent **p_sd)
{
return create_dir(kobj, kobj->sd, name, p_sd);
}
/**
* sysfs_create_dir - create a directory for an object.
* @kobj: object we're creating directory for.
*/
int sysfs_create_dir(struct kobject * kobj)
{
struct sysfs_dirent *parent_sd, *sd;
int error = 0;
BUG_ON(!kobj);
if (kobj->parent)
parent_sd = kobj->parent->sd;
else
parent_sd = &sysfs_root;
error = create_dir(kobj, parent_sd, kobject_name(kobj), &sd);
if (!error)
kobj->sd = sd;
return error;
}
static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
struct dentry *ret = NULL;
struct sysfs_dirent *parent_sd = dentry->d_parent->d_fsdata;
struct sysfs_dirent *sd;
struct inode *inode;
mutex_lock(&sysfs_mutex);
sd = sysfs_find_dirent(parent_sd, dentry->d_name.name);
/* no such entry */
if (!sd) {
ret = ERR_PTR(-ENOENT);
goto out_unlock;
}
/* attach dentry and inode */
inode = sysfs_get_inode(sd);
if (!inode) {
ret = ERR_PTR(-ENOMEM);
goto out_unlock;
}
/* instantiate and hash dentry */
ret = d_find_alias(inode);
if (!ret) {
dentry->d_op = &sysfs_dentry_ops;
dentry->d_fsdata = sysfs_get(sd);
d_add(dentry, inode);
} else {
d_move(ret, dentry);
iput(inode);
}
out_unlock:
mutex_unlock(&sysfs_mutex);
return ret;
}
const struct inode_operations sysfs_dir_inode_operations = {
.lookup = sysfs_lookup,
.permission = sysfs_permission,
.setattr = sysfs_setattr,
.getattr = sysfs_getattr,
.setxattr = sysfs_setxattr,
};
static void remove_dir(struct sysfs_dirent *sd)
{
struct sysfs_addrm_cxt acxt;
sysfs_addrm_start(&acxt, sd->s_parent);
sysfs_remove_one(&acxt, sd);
sysfs_addrm_finish(&acxt);
}
void sysfs_remove_subdir(struct sysfs_dirent *sd)
{
remove_dir(sd);
}
static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
{
struct sysfs_addrm_cxt acxt;
struct sysfs_dirent **pos;
if (!dir_sd)
return;
pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
sysfs_addrm_start(&acxt, dir_sd);
pos = &dir_sd->s_dir.children;
while (*pos) {
struct sysfs_dirent *sd = *pos;
if (sysfs_type(sd) != SYSFS_DIR)
sysfs_remove_one(&acxt, sd);
else
pos = &(*pos)->s_sibling;
}
sysfs_addrm_finish(&acxt);
remove_dir(dir_sd);
}
/**
* sysfs_remove_dir - remove an object's directory.
* @kobj: object.
*
* The only thing special about this is that we remove any files in
* the directory before we remove the directory, and we've inlined
* what used to be sysfs_rmdir() below, instead of calling separately.
*/
void sysfs_remove_dir(struct kobject * kobj)
{
struct sysfs_dirent *sd = kobj->sd;
spin_lock(&sysfs_assoc_lock);
kobj->sd = NULL;
spin_unlock(&sysfs_assoc_lock);
__sysfs_remove_dir(sd);
}
int sysfs_rename(struct sysfs_dirent *sd,
struct sysfs_dirent *new_parent_sd, const char *new_name)
{
const char *dup_name = NULL;
int error;
mutex_lock(&sysfs_mutex);
error = 0;
if ((sd->s_parent == new_parent_sd) &&
(strcmp(sd->s_name, new_name) == 0))
goto out; /* nothing to rename */
error = -EEXIST;
if (sysfs_find_dirent(new_parent_sd, new_name))
goto out;
/* rename sysfs_dirent */
if (strcmp(sd->s_name, new_name) != 0) {
error = -ENOMEM;
new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
if (!new_name)
goto out;
dup_name = sd->s_name;
sd->s_name = new_name;
}
/* Remove from old parent's list and insert into new parent's list. */
if (sd->s_parent != new_parent_sd) {
sysfs_unlink_sibling(sd);
sysfs_get(new_parent_sd);
sysfs_put(sd->s_parent);
sd->s_parent = new_parent_sd;
sysfs_link_sibling(sd);
}
error = 0;
out:
mutex_unlock(&sysfs_mutex);
kfree(dup_name);
return error;
}
int sysfs_rename_dir(struct kobject *kobj, const char *new_name)
{
return sysfs_rename(kobj->sd, kobj->sd->s_parent, new_name);
}
int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
{
struct sysfs_dirent *sd = kobj->sd;
struct sysfs_dirent *new_parent_sd;
BUG_ON(!sd->s_parent);
new_parent_sd = new_parent_kobj && new_parent_kobj->sd ?
new_parent_kobj->sd : &sysfs_root;
return sysfs_rename(sd, new_parent_sd, sd->s_name);
}
/* Relationship between s_mode and the DT_xxx types */
static inline unsigned char dt_type(struct sysfs_dirent *sd)
{
return (sd->s_mode >> 12) & 15;
}
static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
struct dentry *dentry = filp->f_path.dentry;
struct sysfs_dirent * parent_sd = dentry->d_fsdata;
struct sysfs_dirent *pos;
ino_t ino;
if (filp->f_pos == 0) {
ino = parent_sd->s_ino;
if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0)
filp->f_pos++;
}
if (filp->f_pos == 1) {
if (parent_sd->s_parent)
ino = parent_sd->s_parent->s_ino;
else
ino = parent_sd->s_ino;
if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0)
filp->f_pos++;
}
if ((filp->f_pos > 1) && (filp->f_pos < INT_MAX)) {
mutex_lock(&sysfs_mutex);
/* Skip the dentries we have already reported */
pos = parent_sd->s_dir.children;
while (pos && (filp->f_pos > pos->s_ino))
pos = pos->s_sibling;
for ( ; pos; pos = pos->s_sibling) {
const char * name;
int len;
name = pos->s_name;
len = strlen(name);
filp->f_pos = ino = pos->s_ino;
if (filldir(dirent, name, len, filp->f_pos, ino,
dt_type(pos)) < 0)
break;
}
if (!pos)
filp->f_pos = INT_MAX;
mutex_unlock(&sysfs_mutex);
}
return 0;
}
const struct file_operations sysfs_dir_operations = {
.read = generic_read_dir,
.readdir = sysfs_readdir,
.llseek = generic_file_llseek,
};