diff options
Diffstat (limited to 'fs/sysfs/dir.c')
| -rw-r--r-- | fs/sysfs/dir.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index de47ed32d5c7..08c66969d52a 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -26,7 +26,7 @@ #include "sysfs.h" DEFINE_MUTEX(sysfs_mutex); -DEFINE_SPINLOCK(sysfs_assoc_lock); +DEFINE_SPINLOCK(sysfs_symlink_target_lock); #define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb) @@ -902,9 +902,21 @@ void sysfs_remove_dir(struct kobject *kobj) { struct sysfs_dirent *sd = kobj->sd; - spin_lock(&sysfs_assoc_lock); + /* + * In general, kboject owner is responsible for ensuring removal + * doesn't race with other operations and sysfs doesn't provide any + * protection; however, when @kobj is used as a symlink target, the + * symlinking entity usually doesn't own @kobj and thus has no + * control over removal. @kobj->sd may be removed anytime and + * symlink code may end up dereferencing an already freed sd. + * + * sysfs_symlink_target_lock synchronizes @kobj->sd disassociation + * against symlink operations so that symlink code can safely + * dereference @kobj->sd. + */ + spin_lock(&sysfs_symlink_target_lock); kobj->sd = NULL; - spin_unlock(&sysfs_assoc_lock); + spin_unlock(&sysfs_symlink_target_lock); if (sd) { WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR); |