Commit 3007e997 authored by Tejun Heo's avatar Tejun Heo Committed by Greg Kroah-Hartman
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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: default avatarTejun Heo <htejun@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 5f995323

fs/sysfs/dir.c

+71 −30
Original line number Diff line number Diff line
@@ -14,7 +14,7 @@ 
#include <asm/semaphore.h>

#include "sysfs.h"



DECLARE_RWSEM(sysfs_rename_sem);

DEFINE_MUTEX(sysfs_mutex);

spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;



static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
@@ -28,7 +28,7 @@ static DEFINE_IDA(sysfs_ino_ida); 
 *	sd->s_parent->s_children.

 *

 *	Locking:

 *	mutex_lock(sd->s_parent->dentry->d_inode->i_mutex)

 *	mutex_lock(sysfs_mutex)

 */

static void sysfs_link_sibling(struct sysfs_dirent *sd)

{
@@ -47,7 +47,7 @@ static void sysfs_link_sibling(struct sysfs_dirent *sd) 
 *	sd->s_parent->s_children.

 *

 *	Locking:

 *	mutex_lock(sd->s_parent->dentry->d_inode->i_mutex)

 *	mutex_lock(sysfs_mutex)

 */

static void sysfs_unlink_sibling(struct sysfs_dirent *sd)

{
@@ -215,6 +215,9 @@ 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)
@@ -291,6 +294,17 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type) 
	return NULL;

}



/**

 *	sysfs_attach_dentry - associate sysfs_dirent with dentry

 *	@sd: target sysfs_dirent

 *	@dentry: dentry to associate

 *

 *	Associate @sd with @dentry.  This is protected by

 *	sysfs_assoc_lock to avoid race with sysfs_d_iput().

 *

 *	LOCKING:

 *	mutex_lock(sysfs_mutex)

 */

static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry)

{

	dentry->d_op = &sysfs_dentry_ops;
@@ -304,6 +318,17 @@ static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry) 
	d_rehash(dentry);

}



/**

 *	sysfs_attach_dirent - attach sysfs_dirent to its parent and dentry

 *	@sd: sysfs_dirent to attach

 *	@parent_sd: parent to attach to (optional)

 *	@dentry: dentry to be associated to @sd (optional)

 *

 *	Attach @sd to @parent_sd and/or @dentry.  Both are optional.

 *

 *	LOCKING:

 *	mutex_lock(sysfs_mutex)

 */

void sysfs_attach_dirent(struct sysfs_dirent *sd,

			 struct sysfs_dirent *parent_sd, struct dentry *dentry)

{
@@ -324,7 +349,7 @@ void sysfs_attach_dirent(struct sysfs_dirent *sd, 
 *	Look for sysfs_dirent with name @name under @parent_sd.

 *

 *	LOCKING:

 *	mutex_lock(parent->i_mutex)

 *	mutex_lock(sysfs_mutex)

 *

 *	RETURNS:

 *	Pointer to sysfs_dirent if found, NULL if not.
@@ -349,7 +374,7 @@ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd, 
 *	it if found.

 *

 *	LOCKING:

 *	Kernel thread context (may sleep)

 *	Kernel thread context (may sleep).  Grabs sysfs_mutex.

 *

 *	RETURNS:

 *	Pointer to sysfs_dirent if found, NULL if not.
@@ -359,10 +384,10 @@ struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd, 
{

	struct sysfs_dirent *sd;



	mutex_lock(&parent_sd->s_dentry->d_inode->i_mutex);

	mutex_lock(&sysfs_mutex);

	sd = sysfs_find_dirent(parent_sd, name);

	sysfs_get(sd);

	mutex_unlock(&parent_sd->s_dentry->d_inode->i_mutex);

	mutex_unlock(&sysfs_mutex);



	return sd;

}
@@ -408,14 +433,20 @@ static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd, 
	}



	/* link in */

	mutex_lock(&sysfs_mutex);



	error = -EEXIST;

	if (sysfs_find_dirent(parent_sd, name))

	if (sysfs_find_dirent(parent_sd, name)) {

		mutex_unlock(&sysfs_mutex);

		goto out_iput;

	}



	sysfs_instantiate(dentry, inode);

	inc_nlink(parent->d_inode);

	sysfs_attach_dirent(sd, parent_sd, dentry);



	mutex_unlock(&sysfs_mutex);



	*p_sd = sd;

	error = 0;

	goto out_unlock;	/* pin directory dentry in core */
@@ -493,6 +524,8 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry, 
	if (!inode)

		return ERR_PTR(-ENOMEM);



	mutex_lock(&sysfs_mutex);



	if (inode->i_state & I_NEW) {

		/* initialize inode according to type */

		switch (sysfs_type(sd)) {
@@ -516,6 +549,8 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry, 
	sysfs_instantiate(dentry, inode);

	sysfs_attach_dentry(sd, dentry);



	mutex_unlock(&sysfs_mutex);



	return NULL;

}
@@ -526,17 +561,13 @@ const struct inode_operations sysfs_dir_inode_operations = { 


static void remove_dir(struct sysfs_dirent *sd)

{

	struct dentry *parent = sd->s_parent->s_dentry;



	mutex_lock(&parent->d_inode->i_mutex);



	mutex_lock(&sysfs_mutex);

	sysfs_unlink_sibling(sd);

	sd->s_flags |= SYSFS_FLAG_REMOVED;

	mutex_unlock(&sysfs_mutex);



	pr_debug(" o %s removing done\n", sd->s_name);



	mutex_unlock(&parent->d_inode->i_mutex);



	sysfs_drop_dentry(sd);

	sysfs_deactivate(sd);

	sysfs_put(sd);
@@ -552,15 +583,12 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd) 
{

	struct sysfs_dirent *removed = NULL;

	struct sysfs_dirent **pos;

	struct dentry *dir;



	if (!dir_sd)

		return;



	dir = dir_sd->s_dentry;



	pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);

	mutex_lock(&dir->d_inode->i_mutex);

	mutex_lock(&sysfs_mutex);

	pos = &dir_sd->s_children;

	while (*pos) {

		struct sysfs_dirent *sd = *pos;
@@ -573,7 +601,7 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd) 
		} else

			pos = &(*pos)->s_sibling;

	}

	mutex_unlock(&dir->d_inode->i_mutex);

	mutex_unlock(&sysfs_mutex);



	while (removed) {

		struct sysfs_dirent *sd = removed;
@@ -621,7 +649,6 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd, 
	if (!new_parent_sd)

		return -EFAULT;



	down_write(&sysfs_rename_sem);

	mutex_lock(&new_parent->d_inode->i_mutex);



	new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));
@@ -661,12 +688,16 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd, 
	d_add(new_dentry, NULL);

	d_move(sd->s_dentry, new_dentry);



	mutex_lock(&sysfs_mutex);



	sysfs_unlink_sibling(sd);

	sysfs_get(new_parent_sd);

	sysfs_put(sd->s_parent);

	sd->s_parent = new_parent_sd;

	sysfs_link_sibling(sd);



	mutex_unlock(&sysfs_mutex);



	error = 0;

	goto out_unlock;
@@ -678,7 +709,6 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd, 
	dput(new_dentry);

 out_unlock:

	mutex_unlock(&new_parent->d_inode->i_mutex);

	up_write(&sysfs_rename_sem);

	return error;

}
@@ -717,12 +747,15 @@ again: 
	dput(new_dentry);



	/* Remove from old parent's list and insert into new parent's list. */

	mutex_lock(&sysfs_mutex);



	sysfs_unlink_sibling(sd);

	sysfs_get(new_parent_sd);

	sysfs_put(sd->s_parent);

	sd->s_parent = new_parent_sd;

	sysfs_link_sibling(sd);



	mutex_unlock(&sysfs_mutex);

out:

	mutex_unlock(&new_parent_dentry->d_inode->i_mutex);

	mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
@@ -736,11 +769,12 @@ static int sysfs_dir_open(struct inode *inode, struct file *file) 
	struct sysfs_dirent * parent_sd = dentry->d_fsdata;

	struct sysfs_dirent * sd;



	mutex_lock(&dentry->d_inode->i_mutex);

	sd = sysfs_new_dirent("_DIR_", 0, 0);

	if (sd)

	if (sd) {

		mutex_lock(&sysfs_mutex);

		sysfs_attach_dirent(sd, parent_sd, NULL);

	mutex_unlock(&dentry->d_inode->i_mutex);

		mutex_unlock(&sysfs_mutex);

	}



	file->private_data = sd;

	return sd ? 0 : -ENOMEM;
@@ -748,12 +782,11 @@ static int sysfs_dir_open(struct inode *inode, struct file *file) 


static int sysfs_dir_close(struct inode *inode, struct file *file)

{

	struct dentry * dentry = file->f_path.dentry;

	struct sysfs_dirent * cursor = file->private_data;



	mutex_lock(&dentry->d_inode->i_mutex);

	mutex_lock(&sysfs_mutex);

	sysfs_unlink_sibling(cursor);

	mutex_unlock(&dentry->d_inode->i_mutex);

	mutex_unlock(&sysfs_mutex);



	release_sysfs_dirent(cursor);
@@ -794,6 +827,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir) 
			i++;

			/* fallthrough */

		default:

			mutex_lock(&sysfs_mutex);



			pos = &parent_sd->s_children;

			while (*pos != cursor)

				pos = &(*pos)->s_sibling;
@@ -826,6 +861,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir) 
			/* put cursor back in */

			cursor->s_sibling = *pos;

			*pos = cursor;



			mutex_unlock(&sysfs_mutex);

	}

	return 0;

}
@@ -834,7 +871,6 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin) 
{

	struct dentry * dentry = file->f_path.dentry;



	mutex_lock(&dentry->d_inode->i_mutex);

	switch (origin) {

		case 1:

			offset += file->f_pos;
@@ -842,10 +878,11 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin) 
			if (offset >= 0)

				break;

		default:

			mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);

			return -EINVAL;

	}

	if (offset != file->f_pos) {

		mutex_lock(&sysfs_mutex);



		file->f_pos = offset;

		if (file->f_pos >= 2) {

			struct sysfs_dirent *sd = dentry->d_fsdata;
@@ -866,8 +903,10 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin) 
			cursor->s_sibling = *pos;

			*pos = cursor;

		}



		mutex_unlock(&sysfs_mutex);

	}

	mutex_unlock(&dentry->d_inode->i_mutex);



	return offset;

}
@@ -933,7 +972,9 @@ struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj) 
	sd->s_elem.dir.kobj = kobj;

	/* point to parent_sd but don't attach to it */

	sd->s_parent = sysfs_get(parent_sd);

	mutex_lock(&sysfs_mutex);

	sysfs_attach_dirent(sd, NULL, shadow);

	mutex_unlock(&sysfs_mutex);



	d_instantiate(shadow, igrab(inode));

	inc_nlink(inode);

fs/sysfs/file.c

+15 −16
Original line number Diff line number Diff line
@@ -415,29 +415,28 @@ const struct file_operations sysfs_file_operations = { 
int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,

		   int type)

{

	struct dentry *dir = dir_sd->s_dentry;

	umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;

	struct sysfs_dirent *sd;

	int error = 0;



	mutex_lock(&dir->d_inode->i_mutex);



	if (sysfs_find_dirent(dir_sd, attr->name)) {

		error = -EEXIST;

		goto out_unlock;

	}



	sd = sysfs_new_dirent(attr->name, mode, type);

	if (!sd) {

		error = -ENOMEM;

		goto out_unlock;

	}

	if (!sd)

		return -ENOMEM;

	sd->s_elem.attr.attr = (void *)attr;



	mutex_lock(&sysfs_mutex);



	if (!sysfs_find_dirent(dir_sd, attr->name)) {

		sysfs_attach_dirent(sd, dir_sd, NULL);

		sd = NULL;

	}



 out_unlock:

	mutex_unlock(&dir->d_inode->i_mutex);

	return error;

	mutex_unlock(&sysfs_mutex);



	if (sd) {

		sysfs_put(sd);

		return -EEXIST;

	}

	return 0;

}

fs/sysfs/inode.c

+3 −8
Original line number Diff line number Diff line
@@ -277,20 +277,14 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd) 


int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)

{

	struct dentry *dir;

	struct sysfs_dirent **pos, *sd;

	int found = 0;



	if (!dir_sd)

		return -ENOENT;



	dir = dir_sd->s_dentry;

	mutex_lock(&sysfs_mutex);



	if (dir->d_inode == NULL)

		/* no inode means this hasn't been made visible yet */

		return -ENOENT;



	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);

	for (pos = &dir_sd->s_children; *pos; pos = &(*pos)->s_sibling) {

		sd = *pos;
@@ -304,7 +298,8 @@ int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name) 
			break;

		}

	}

	mutex_unlock(&dir->d_inode->i_mutex);



	mutex_unlock(&sysfs_mutex);



	if (!found)

		return -ENOENT;

fs/sysfs/symlink.c

+26 −25
Original line number Diff line number Diff line
@@ -44,20 +44,6 @@ static void fill_object_path(struct sysfs_dirent *sd, char *buffer, int length) 
	}

}



static int sysfs_add_link(struct sysfs_dirent * parent_sd, const char * name,

			  struct sysfs_dirent * target_sd)

{

	struct sysfs_dirent * sd;



	sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);

	if (!sd)

		return -ENOMEM;



	sd->s_elem.symlink.target_sd = target_sd;

	sysfs_attach_dirent(sd, parent_sd, NULL);

	return 0;

}



/**

 *	sysfs_create_link - create symlink between two objects.

 *	@kobj:	object whose directory we're creating the link in.
@@ -68,7 +54,8 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char 
{

	struct sysfs_dirent *parent_sd = NULL;

	struct sysfs_dirent *target_sd = NULL;

	int error = -EEXIST;

	struct sysfs_dirent *sd = NULL;

	int error;



	BUG_ON(!name);
@@ -78,8 +65,9 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char 
	} 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;

}

fs/sysfs/sysfs.h

+1 −1
Original line number Diff line number Diff line
@@ -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;

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