sysfs, kernfs: revamp sysfs_dirent active_ref lockdep annotation

Currently, sysfs_dirent active_ref lockdep annotation uses
attribute->[s]key as the lockdep key, which forces
kernfs_create_file_ns() to assume that sysfs_dirent->priv is pointing
to a struct attribute which may not be true for non-sysfs users.  This
patch restructures the lockdep annotation such that

* kernfs_ops contains lockdep_key which is used by default for files
  created kernfs_create_file_ns().

* kernfs_create_file_ns_key() is introduced which takes an extra @key
  argument.  The created file will use the specified key for
  active_ref lockdep annotation.  If NULL is specified, lockdep for
  the file is disabled.

* sysfs_add_file_mode_ns() is updated to use
  kernfs_create_file_ns_key() with the appropriate key from the
  attribute or NULL if ignore_lockdep is set.

This makes the lockdep annotation properly contained in kernfs while
allowing sysfs to cleanly keep its current behavior.  This patch
doesn't introduce any behavior differences.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1 insertions, 31 deletions

diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index c86456c9b19e..e93f8b845611 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -92,43 +92,13 @@ struct sysfs_dirent {
 #define SYSFS_FLAG_NS                   0x0020
 #define SYSFS_FLAG_HAS_SEQ_SHOW         0x0040
 #define SYSFS_FLAG_HAS_MMAP             0x0080
+#define SYSFS_FLAG_LOCKDEP              0x0100
 
 static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
 {
         return sd->s_flags & SYSFS_TYPE_MASK;
 }
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-
-#define sysfs_dirent_init_lockdep(sd)                           \
-do {                                                            \
-        struct attribute *attr = sd->priv;                      \
-        struct lock_class_key *key = attr->key;                 \
-        if (!key)                                               \
-                key = &attr->skey;                              \
-                                                                \
-        lockdep_init_map(&sd->dep_map, "s_active", key, 0);     \
-} while (0)
-
-/* Test for attributes that want to ignore lockdep for read-locking */
-static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd)
-{
-        struct attribute *attr = sd->priv;
-
-        return sysfs_type(sd) == SYSFS_KOBJ_ATTR && attr->ignore_lockdep;
-}
-
-#else
-
-#define sysfs_dirent_init_lockdep(sd) do {} while (0)
-
-static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd)
-{
-        return true;
-}
-
-#endif
-
 /*
  * Context structure to be used while adding/removing nodes.
  */