Skip to content

Commit

Permalink
sysfs: use sysfs_mutex to protect the sysfs_dirent tree
Browse files Browse the repository at this point in the history 
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>
  • Loading branch information
Tejun Heo authored and Greg Kroah-Hartman committed Jul 11, 2007
1 parent 5f99532 commit 3007e99
Show file tree
Hide file tree
Showing 5 changed files with 116 additions and 80 deletions.
101 changes: 71 additions & 30 deletions fs/sysfs/dir.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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)
{
Expand All @@ -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)
{
Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -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;
Expand All @@ -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)
{
Expand All @@ -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.
Expand All @@ -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.
Expand All @@ -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;
}
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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)) {
Expand All @@ -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;
}

Expand All @@ -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);
Expand All @@ -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;
Expand All @@ -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;
Expand Down Expand Up @@ -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));
Expand Down Expand Up @@ -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;

Expand All @@ -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;
}

Expand Down Expand Up @@ -717,12 +747,15 @@ int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
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);
Expand All @@ -736,24 +769,24 @@ 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;
}

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);

Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
}
Expand All @@ -834,18 +871,18 @@ 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;
case 0:
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;
Expand All @@ -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;
}

Expand Down Expand Up @@ -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);
Expand Down
31 changes: 15 additions & 16 deletions fs/sysfs/file.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
sd = sysfs_new_dirent(attr->name, mode, type);
if (!sd)
return -ENOMEM;
sd->s_elem.attr.attr = (void *)attr;

if (sysfs_find_dirent(dir_sd, attr->name)) {
error = -EEXIST;
goto out_unlock;
}
mutex_lock(&sysfs_mutex);

sd = sysfs_new_dirent(attr->name, mode, type);
if (!sd) {
error = -ENOMEM;
goto out_unlock;
if (!sysfs_find_dirent(dir_sd, attr->name)) {
sysfs_attach_dirent(sd, dir_sd, NULL);
sd = NULL;
}
sd->s_elem.attr.attr = (void *)attr;
sysfs_attach_dirent(sd, dir_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;
}


Expand Down
Loading

0 comments on commit 3007e99

Please sign in to comment.