diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2007-08-20 21:36:30 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2007-10-12 14:51:08 -0700 |
| commit | 932ea2e374dd1ca26676297a5eccd1cdab86f7cd (patch) | |
| tree | 83bba794de7f1f9f9290192f4f95a8ed9c91dfb6 | |
| parent | 89bec09705d2033b8b765f3c3ac5093f80bd5bc4 (diff) | |
sysfs: Introduce sysfs_rename_mutex
Looking carefully at the rename code we have a subtle dependency
that the structure of sysfs not change while we are performing
a rename. If the parent directory of the object we are renaming
changes while the rename is being performed nasty things could
happen when we go to release our locks.
So introduce a sysfs_rename_mutex to prevent this highly
unlikely theoretical issue.
In addition hold sysfs_rename_mutex over all calls to
sysfs_get_dentry. Allowing sysfs_get_dentry to be simplified
in the future.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | fs/sysfs/dir.c | 8 | ||||
| -rw-r--r-- | fs/sysfs/file.c | 4 | ||||
| -rw-r--r-- | fs/sysfs/sysfs.h | 1 |
3 files changed, 12 insertions, 1 deletions
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 1af963e66e3..9fe83d23dc2 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -15,6 +15,7 @@ #include "sysfs.h" DEFINE_MUTEX(sysfs_mutex); +DEFINE_MUTEX(sysfs_rename_mutex); spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED; static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED; @@ -82,7 +83,7 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd) * down from there looking up dentry for each step. * * LOCKING: - * Kernel thread context (may sleep) + * mutex_lock(sysfs_rename_mutex) * * RETURNS: * Pointer to found dentry on success, ERR_PTR() value on error. @@ -858,6 +859,8 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name) const char *dup_name = NULL; int error; + mutex_lock(&sysfs_rename_mutex); + /* get the original dentry */ sd = kobj->sd; old_dentry = sysfs_get_dentry(sd); @@ -915,6 +918,7 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name) kfree(dup_name); dput(old_dentry); dput(new_dentry); + mutex_unlock(&sysfs_rename_mutex); return error; } @@ -926,6 +930,7 @@ int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj) struct dentry *old_dentry = NULL, *new_dentry = NULL; int error; + mutex_lock(&sysfs_rename_mutex); BUG_ON(!sd->s_parent); new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root; @@ -982,6 +987,7 @@ again: dput(new_parent); dput(old_dentry); dput(new_dentry); + mutex_unlock(&sysfs_rename_mutex); return error; } diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 16f39c30b09..ff93c92164b 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -470,7 +470,9 @@ int sysfs_update_file(struct kobject * kobj, const struct attribute * attr) if (!victim_sd) goto out; + mutex_lock(&sysfs_rename_mutex); victim = sysfs_get_dentry(victim_sd); + mutex_unlock(&sysfs_rename_mutex); if (IS_ERR(victim)) { rc = PTR_ERR(victim); victim = NULL; @@ -509,7 +511,9 @@ int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode) if (!victim_sd) goto out; + mutex_lock(&sysfs_rename_mutex); victim = sysfs_get_dentry(victim_sd); + mutex_unlock(&sysfs_rename_mutex); if (IS_ERR(victim)) { rc = PTR_ERR(victim); victim = NULL; diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h index 77253aabc4a..179e6a26ece 100644 --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -90,6 +90,7 @@ extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr); extern spinlock_t sysfs_assoc_lock; extern struct mutex sysfs_mutex; +extern struct mutex sysfs_rename_mutex; extern struct super_block * sysfs_sb; extern const struct file_operations sysfs_dir_operations; extern const struct file_operations sysfs_file_operations; |