sysfs: use sysfs_mutex to protect the sysfs_dirent tree
As kobj sysfs dentries and inodes are gonna be made reclaimable, i_mutex can't be used to protect sysfs_dirent tree. Use sysfs_mutex globally instead. As the whole tree is protected with sysfs_mutex, there is no reason to keep sysfs_rename_sem. Drop it. While at it, add docbook comments to functions which require sysfs_mutex locking. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
parent
5f9953237f
commit
3007e997de
101
fs/sysfs/dir.c
101
fs/sysfs/dir.c
@ -14,7 +14,7 @@
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#include <asm/semaphore.h>
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#include "sysfs.h"
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DECLARE_RWSEM(sysfs_rename_sem);
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DEFINE_MUTEX(sysfs_mutex);
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spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;
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static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
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@ -28,7 +28,7 @@ static DEFINE_IDA(sysfs_ino_ida);
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* sd->s_parent->s_children.
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*
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* Locking:
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* mutex_lock(sd->s_parent->dentry->d_inode->i_mutex)
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* mutex_lock(sysfs_mutex)
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*/
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static void sysfs_link_sibling(struct sysfs_dirent *sd)
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{
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@ -47,7 +47,7 @@ static void sysfs_link_sibling(struct sysfs_dirent *sd)
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* sd->s_parent->s_children.
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*
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* Locking:
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* mutex_lock(sd->s_parent->dentry->d_inode->i_mutex)
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* mutex_lock(sysfs_mutex)
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*/
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static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
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{
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@ -215,6 +215,9 @@ void release_sysfs_dirent(struct sysfs_dirent * sd)
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struct sysfs_dirent *parent_sd;
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repeat:
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/* Moving/renaming is always done while holding reference.
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* sd->s_parent won't change beneath us.
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*/
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parent_sd = sd->s_parent;
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if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
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@ -291,6 +294,17 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
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return NULL;
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}
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/**
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* sysfs_attach_dentry - associate sysfs_dirent with dentry
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* @sd: target sysfs_dirent
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* @dentry: dentry to associate
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*
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* Associate @sd with @dentry. This is protected by
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* sysfs_assoc_lock to avoid race with sysfs_d_iput().
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*
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* LOCKING:
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* mutex_lock(sysfs_mutex)
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*/
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static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry)
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{
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dentry->d_op = &sysfs_dentry_ops;
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@ -304,6 +318,17 @@ static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry)
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d_rehash(dentry);
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}
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/**
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* sysfs_attach_dirent - attach sysfs_dirent to its parent and dentry
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* @sd: sysfs_dirent to attach
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* @parent_sd: parent to attach to (optional)
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* @dentry: dentry to be associated to @sd (optional)
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*
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* Attach @sd to @parent_sd and/or @dentry. Both are optional.
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*
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* LOCKING:
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* mutex_lock(sysfs_mutex)
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*/
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void sysfs_attach_dirent(struct sysfs_dirent *sd,
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struct sysfs_dirent *parent_sd, struct dentry *dentry)
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{
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@ -324,7 +349,7 @@ void sysfs_attach_dirent(struct sysfs_dirent *sd,
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* Look for sysfs_dirent with name @name under @parent_sd.
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*
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* LOCKING:
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* mutex_lock(parent->i_mutex)
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* mutex_lock(sysfs_mutex)
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*
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* RETURNS:
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* Pointer to sysfs_dirent if found, NULL if not.
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@ -349,7 +374,7 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
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* it if found.
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*
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* LOCKING:
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* Kernel thread context (may sleep)
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* Kernel thread context (may sleep). Grabs sysfs_mutex.
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*
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* RETURNS:
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* Pointer to sysfs_dirent if found, NULL if not.
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@ -359,10 +384,10 @@ struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
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{
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struct sysfs_dirent *sd;
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mutex_lock(&parent_sd->s_dentry->d_inode->i_mutex);
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mutex_lock(&sysfs_mutex);
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sd = sysfs_find_dirent(parent_sd, name);
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sysfs_get(sd);
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mutex_unlock(&parent_sd->s_dentry->d_inode->i_mutex);
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mutex_unlock(&sysfs_mutex);
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return sd;
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}
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@ -408,14 +433,20 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
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}
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/* link in */
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mutex_lock(&sysfs_mutex);
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error = -EEXIST;
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if (sysfs_find_dirent(parent_sd, name))
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if (sysfs_find_dirent(parent_sd, name)) {
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mutex_unlock(&sysfs_mutex);
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goto out_iput;
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}
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sysfs_instantiate(dentry, inode);
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inc_nlink(parent->d_inode);
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sysfs_attach_dirent(sd, parent_sd, dentry);
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mutex_unlock(&sysfs_mutex);
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*p_sd = sd;
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error = 0;
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goto out_unlock; /* pin directory dentry in core */
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@ -493,6 +524,8 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
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if (!inode)
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return ERR_PTR(-ENOMEM);
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mutex_lock(&sysfs_mutex);
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if (inode->i_state & I_NEW) {
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/* initialize inode according to type */
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switch (sysfs_type(sd)) {
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@ -516,6 +549,8 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
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sysfs_instantiate(dentry, inode);
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sysfs_attach_dentry(sd, dentry);
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mutex_unlock(&sysfs_mutex);
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return NULL;
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}
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@ -526,17 +561,13 @@ const struct inode_operations sysfs_dir_inode_operations = {
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static void remove_dir(struct sysfs_dirent *sd)
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{
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struct dentry *parent = sd->s_parent->s_dentry;
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mutex_lock(&parent->d_inode->i_mutex);
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mutex_lock(&sysfs_mutex);
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sysfs_unlink_sibling(sd);
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sd->s_flags |= SYSFS_FLAG_REMOVED;
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mutex_unlock(&sysfs_mutex);
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pr_debug(" o %s removing done\n", sd->s_name);
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mutex_unlock(&parent->d_inode->i_mutex);
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sysfs_drop_dentry(sd);
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sysfs_deactivate(sd);
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sysfs_put(sd);
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@ -552,15 +583,12 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
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{
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struct sysfs_dirent *removed = NULL;
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struct sysfs_dirent **pos;
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struct dentry *dir;
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if (!dir_sd)
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return;
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dir = dir_sd->s_dentry;
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pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
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mutex_lock(&dir->d_inode->i_mutex);
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mutex_lock(&sysfs_mutex);
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pos = &dir_sd->s_children;
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while (*pos) {
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struct sysfs_dirent *sd = *pos;
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@ -573,7 +601,7 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
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} else
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pos = &(*pos)->s_sibling;
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}
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mutex_unlock(&dir->d_inode->i_mutex);
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mutex_unlock(&sysfs_mutex);
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while (removed) {
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struct sysfs_dirent *sd = removed;
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@ -621,7 +649,6 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
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if (!new_parent_sd)
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return -EFAULT;
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down_write(&sysfs_rename_sem);
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mutex_lock(&new_parent->d_inode->i_mutex);
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new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));
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@ -661,12 +688,16 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
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d_add(new_dentry, NULL);
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d_move(sd->s_dentry, new_dentry);
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mutex_lock(&sysfs_mutex);
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sysfs_unlink_sibling(sd);
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sysfs_get(new_parent_sd);
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sysfs_put(sd->s_parent);
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sd->s_parent = new_parent_sd;
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sysfs_link_sibling(sd);
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mutex_unlock(&sysfs_mutex);
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error = 0;
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goto out_unlock;
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@ -678,7 +709,6 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
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dput(new_dentry);
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out_unlock:
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mutex_unlock(&new_parent->d_inode->i_mutex);
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up_write(&sysfs_rename_sem);
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return error;
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}
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@ -717,12 +747,15 @@ int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
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dput(new_dentry);
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/* Remove from old parent's list and insert into new parent's list. */
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mutex_lock(&sysfs_mutex);
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sysfs_unlink_sibling(sd);
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sysfs_get(new_parent_sd);
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sysfs_put(sd->s_parent);
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sd->s_parent = new_parent_sd;
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sysfs_link_sibling(sd);
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mutex_unlock(&sysfs_mutex);
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out:
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mutex_unlock(&new_parent_dentry->d_inode->i_mutex);
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mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
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@ -736,11 +769,12 @@ static int sysfs_dir_open(struct inode *inode, struct file *file)
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struct sysfs_dirent * parent_sd = dentry->d_fsdata;
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struct sysfs_dirent * sd;
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mutex_lock(&dentry->d_inode->i_mutex);
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sd = sysfs_new_dirent("_DIR_", 0, 0);
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if (sd)
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if (sd) {
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mutex_lock(&sysfs_mutex);
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sysfs_attach_dirent(sd, parent_sd, NULL);
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mutex_unlock(&dentry->d_inode->i_mutex);
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mutex_unlock(&sysfs_mutex);
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}
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file->private_data = sd;
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return sd ? 0 : -ENOMEM;
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@ -748,12 +782,11 @@ static int sysfs_dir_open(struct inode *inode, struct file *file)
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static int sysfs_dir_close(struct inode *inode, struct file *file)
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{
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struct dentry * dentry = file->f_path.dentry;
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struct sysfs_dirent * cursor = file->private_data;
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mutex_lock(&dentry->d_inode->i_mutex);
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mutex_lock(&sysfs_mutex);
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sysfs_unlink_sibling(cursor);
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mutex_unlock(&dentry->d_inode->i_mutex);
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mutex_unlock(&sysfs_mutex);
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release_sysfs_dirent(cursor);
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@ -794,6 +827,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
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i++;
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/* fallthrough */
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default:
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mutex_lock(&sysfs_mutex);
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pos = &parent_sd->s_children;
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while (*pos != cursor)
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pos = &(*pos)->s_sibling;
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@ -826,6 +861,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
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/* put cursor back in */
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cursor->s_sibling = *pos;
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*pos = cursor;
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mutex_unlock(&sysfs_mutex);
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}
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return 0;
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}
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@ -834,7 +871,6 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
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{
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struct dentry * dentry = file->f_path.dentry;
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mutex_lock(&dentry->d_inode->i_mutex);
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switch (origin) {
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case 1:
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offset += file->f_pos;
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@ -842,10 +878,11 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
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if (offset >= 0)
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break;
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default:
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mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
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return -EINVAL;
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}
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if (offset != file->f_pos) {
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mutex_lock(&sysfs_mutex);
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file->f_pos = offset;
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if (file->f_pos >= 2) {
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struct sysfs_dirent *sd = dentry->d_fsdata;
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@ -866,8 +903,10 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
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cursor->s_sibling = *pos;
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*pos = cursor;
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}
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mutex_unlock(&sysfs_mutex);
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}
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mutex_unlock(&dentry->d_inode->i_mutex);
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return offset;
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}
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@ -933,7 +972,9 @@ struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj)
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sd->s_elem.dir.kobj = kobj;
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/* point to parent_sd but don't attach to it */
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sd->s_parent = sysfs_get(parent_sd);
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mutex_lock(&sysfs_mutex);
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sysfs_attach_dirent(sd, NULL, shadow);
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mutex_unlock(&sysfs_mutex);
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d_instantiate(shadow, igrab(inode));
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inc_nlink(inode);
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@ -415,29 +415,28 @@ const struct file_operations sysfs_file_operations = {
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int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
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int type)
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{
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struct dentry *dir = dir_sd->s_dentry;
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umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
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struct sysfs_dirent *sd;
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int error = 0;
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mutex_lock(&dir->d_inode->i_mutex);
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if (sysfs_find_dirent(dir_sd, attr->name)) {
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error = -EEXIST;
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goto out_unlock;
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}
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sd = sysfs_new_dirent(attr->name, mode, type);
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if (!sd) {
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error = -ENOMEM;
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goto out_unlock;
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}
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if (!sd)
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return -ENOMEM;
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sd->s_elem.attr.attr = (void *)attr;
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sysfs_attach_dirent(sd, dir_sd, NULL);
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out_unlock:
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mutex_unlock(&dir->d_inode->i_mutex);
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return error;
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mutex_lock(&sysfs_mutex);
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if (!sysfs_find_dirent(dir_sd, attr->name)) {
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sysfs_attach_dirent(sd, dir_sd, NULL);
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sd = NULL;
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}
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mutex_unlock(&sysfs_mutex);
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if (sd) {
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sysfs_put(sd);
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return -EEXIST;
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}
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return 0;
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}
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@ -277,20 +277,14 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
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int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
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{
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struct dentry *dir;
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struct sysfs_dirent **pos, *sd;
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int found = 0;
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if (!dir_sd)
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return -ENOENT;
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dir = dir_sd->s_dentry;
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mutex_lock(&sysfs_mutex);
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if (dir->d_inode == NULL)
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/* no inode means this hasn't been made visible yet */
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return -ENOENT;
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mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
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for (pos = &dir_sd->s_children; *pos; pos = &(*pos)->s_sibling) {
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sd = *pos;
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@ -304,7 +298,8 @@ int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
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break;
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}
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}
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mutex_unlock(&dir->d_inode->i_mutex);
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mutex_unlock(&sysfs_mutex);
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if (!found)
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return -ENOENT;
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@ -44,20 +44,6 @@ static void fill_object_path(struct sysfs_dirent *sd, char *buffer, int length)
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}
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}
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static int sysfs_add_link(struct sysfs_dirent * parent_sd, const char * name,
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struct sysfs_dirent * target_sd)
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{
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struct sysfs_dirent * sd;
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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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return -ENOMEM;
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sd->s_elem.symlink.target_sd = target_sd;
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sysfs_attach_dirent(sd, parent_sd, NULL);
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return 0;
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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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@ -68,7 +54,8 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
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{
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struct sysfs_dirent *parent_sd = NULL;
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struct sysfs_dirent *target_sd = NULL;
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int error = -EEXIST;
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struct sysfs_dirent *sd = NULL;
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int error;
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BUG_ON(!name);
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@ -78,8 +65,9 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
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} else
|
||||
parent_sd = kobj->sd;
|
||||
|
||||
error = -EFAULT;
|
||||
if (!parent_sd)
|
||||
return -EFAULT;
|
||||
goto out_put;
|
||||
|
||||
/* target->sd can go away beneath us but is protected with
|
||||
* sysfs_assoc_lock. Fetch target_sd from it.
|
||||
@ -89,17 +77,30 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
|
||||
target_sd = sysfs_get(target->sd);
|
||||
spin_unlock(&sysfs_assoc_lock);
|
||||
|
||||
error = -ENOENT;
|
||||
if (!target_sd)
|
||||
return -ENOENT;
|
||||
goto out_put;
|
||||
|
||||
mutex_lock(&parent_sd->s_dentry->d_inode->i_mutex);
|
||||
if (!sysfs_find_dirent(parent_sd, name))
|
||||
error = sysfs_add_link(parent_sd, name, target_sd);
|
||||
mutex_unlock(&parent_sd->s_dentry->d_inode->i_mutex);
|
||||
error = -ENOMEM;
|
||||
sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
|
||||
if (!sd)
|
||||
goto out_put;
|
||||
sd->s_elem.symlink.target_sd = target_sd;
|
||||
|
||||
if (error)
|
||||
sysfs_put(target_sd);
|
||||
mutex_lock(&sysfs_mutex);
|
||||
error = -EEXIST;
|
||||
if (sysfs_find_dirent(parent_sd, name))
|
||||
goto out_unlock;
|
||||
sysfs_attach_dirent(sd, parent_sd, NULL);
|
||||
mutex_unlock(&sysfs_mutex);
|
||||
|
||||
return 0;
|
||||
|
||||
out_unlock:
|
||||
mutex_unlock(&sysfs_mutex);
|
||||
out_put:
|
||||
sysfs_put(target_sd);
|
||||
sysfs_put(sd);
|
||||
return error;
|
||||
}
|
||||
|
||||
@ -144,9 +145,9 @@ static int sysfs_getlink(struct dentry *dentry, char * path)
|
||||
struct sysfs_dirent *target_sd = sd->s_elem.symlink.target_sd;
|
||||
int error;
|
||||
|
||||
down_read(&sysfs_rename_sem);
|
||||
mutex_lock(&sysfs_mutex);
|
||||
error = sysfs_get_target_path(parent_sd, target_sd, path);
|
||||
up_read(&sysfs_rename_sem);
|
||||
mutex_unlock(&sysfs_mutex);
|
||||
|
||||
return error;
|
||||
}
|
||||
|
@ -82,7 +82,7 @@ extern void sysfs_drop_dentry(struct sysfs_dirent *sd);
|
||||
extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
|
||||
|
||||
extern spinlock_t sysfs_assoc_lock;
|
||||
extern struct rw_semaphore sysfs_rename_sem;
|
||||
extern struct mutex sysfs_mutex;
|
||||
extern struct super_block * sysfs_sb;
|
||||
extern const struct file_operations sysfs_dir_operations;
|
||||
extern const struct file_operations sysfs_file_operations;
|
||||
|
Loading…
Reference in New Issue
Block a user