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| 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 /fs/sysfs/dir.c | |
| parent | 89bec09705d2033b8b765f3c3ac5093f80bd5bc4 (diff) | |
| download | linux-932ea2e374dd1ca26676297a5eccd1cdab86f7cd.tar.bz2 | |
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>
Diffstat (limited to 'fs/sysfs/dir.c')
| -rw-r--r-- | fs/sysfs/dir.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 1af963e66e3c..9fe83d23dc2c 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; } |