Commit 517e64f5 authored by Tejun Heo's avatar Tejun Heo Committed by Greg Kroah-Hartman
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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: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2b25a629

fs/sysfs/dir.c

+2 −2
Original line number Diff line number Diff line
@@ -150,7 +150,7 @@ struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd) 
	if (!atomic_inc_unless_negative(&sd->s_active))

		return NULL;



	if (likely(!sysfs_ignore_lockdep(sd)))

	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)

		rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);

	return sd;

}
@@ -169,7 +169,7 @@ void sysfs_put_active(struct sysfs_dirent *sd) 
	if (unlikely(!sd))

		return;



	if (likely(!sysfs_ignore_lockdep(sd)))

	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)

		rwsem_release(&sd->dep_map, 1, _RET_IP_);

	v = atomic_dec_return(&sd->s_active);

	if (likely(v != SD_DEACTIVATED_BIAS))

fs/sysfs/file.c

+24 −11
Original line number Diff line number Diff line
@@ -58,7 +58,7 @@ static struct sysfs_open_file *sysfs_of(struct file *file) 
 */

static const struct kernfs_ops *kernfs_ops(struct sysfs_dirent *sd)

{

	if (!sysfs_ignore_lockdep(sd))

	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)

		lockdep_assert_held(sd);

	return sd->s_attr.ops;

}
@@ -71,7 +71,7 @@ static const struct sysfs_ops *sysfs_file_ops(struct sysfs_dirent *sd) 
{

	struct kobject *kobj = sd->s_parent->priv;



	if (!sysfs_ignore_lockdep(sd))

	if (sd->s_flags & SYSFS_FLAG_LOCKDEP)

		lockdep_assert_held(sd);

	return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;

}
@@ -942,6 +942,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd, 
			   const struct attribute *attr, bool is_bin,

			   umode_t mode, const void *ns)

{

	struct lock_class_key *key = NULL;

	const struct kernfs_ops *ops;

	struct sysfs_dirent *sd;

	loff_t size;
@@ -981,8 +982,12 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd, 
		size = battr->size;

	}



	sd = kernfs_create_file_ns(dir_sd, attr->name, mode, size,

				   ops, (void *)attr, ns);

#ifdef CONFIG_DEBUG_LOCK_ALLOC

	if (!attr->ignore_lockdep)

		key = attr->key ?: (struct lock_class_key *)&attr->skey;

#endif

	sd = kernfs_create_file_ns_key(dir_sd, attr->name, mode, size,

				       ops, (void *)attr, ns, key);

	if (IS_ERR(sd)) {

		if (PTR_ERR(sd) == -EEXIST)

			sysfs_warn_dup(dir_sd, attr->name);
@@ -992,7 +997,7 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd, 
}



/**

 * kernfs_create_file_ns - create a file

 * kernfs_create_file_ns_key - create a file

 * @parent: directory to create the file in

 * @name: name of the file

 * @mode: mode of the file
@@ -1000,14 +1005,16 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd, 
 * @ops: kernfs operations for the file

 * @priv: private data for the file

 * @ns: optional namespace tag of the file

 * @key: lockdep key for the file's active_ref, %NULL to disable lockdep

 *

 * Returns the created node on success, ERR_PTR() value on error.

 */

struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,

struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,

					       const char *name,

					       umode_t mode, loff_t size,

					       const struct kernfs_ops *ops,

					   void *priv, const void *ns)

					       void *priv, const void *ns,

					       struct lock_class_key *key)

{

	struct sysfs_addrm_cxt acxt;

	struct sysfs_dirent *sd;
@@ -1022,7 +1029,13 @@ struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent, 
	sd->s_attr.size = size;

	sd->s_ns = ns;

	sd->priv = priv;

	sysfs_dirent_init_lockdep(sd);



#ifdef CONFIG_DEBUG_LOCK_ALLOC

	if (key) {

		lockdep_init_map(&sd->dep_map, "s_active", key, 0);

		sd->s_flags |= SYSFS_FLAG_LOCKDEP;

	}

#endif



	/*

	 * sd->s_attr.ops is accesible only while holding active ref.  We

fs/sysfs/sysfs.h

+1 −31
Original line number Diff line number Diff line
@@ -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.

 */

include/linux/kernfs.h

+29 −8
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include <linux/err.h>

#include <linux/list.h>

#include <linux/mutex.h>

#include <linux/lockdep.h>



struct file;

struct iattr;
@@ -62,6 +63,10 @@ struct kernfs_ops { 
			 loff_t off);



	int (*mmap)(struct sysfs_open_file *of, struct vm_area_struct *vma);



#ifdef CONFIG_DEBUG_LOCK_ALLOC

	struct lock_class_key	lockdep_key;

#endif

};



#ifdef CONFIG_SYSFS
@@ -69,11 +74,12 @@ struct kernfs_ops { 
struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent,

					  const char *name, void *priv,

					  const void *ns);

struct sysfs_dirent *kernfs_create_file_ns(struct sysfs_dirent *parent,

struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,

					       const char *name,

					       umode_t mode, loff_t size,

					       const struct kernfs_ops *ops,

					   void *priv, const void *ns);

					       void *priv, const void *ns,

					       struct lock_class_key *key);

struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,

					const char *name,

					struct sysfs_dirent *target);
@@ -94,9 +100,10 @@ kernfs_create_dir_ns(struct sysfs_dirent *parent, const char *name, void *priv, 
{ return ERR_PTR(-ENOSYS); }



static inline struct sysfs_dirent *

kernfs_create_file_ns(struct sysfs_dirent *parent, const char *name,

		      umode_t mode, loff_t size, const struct kernfs_ops *ops,

		      void *priv, const void *ns)

kernfs_create_file_ns_key(struct sysfs_dirent *parent, const char *name,

			  umode_t mode, loff_t size,

			  const struct kernfs_ops *ops, void *priv,

			  const void *ns, struct lock_class_key *key)

{ return ERR_PTR(-ENOSYS); }



static inline struct sysfs_dirent *
@@ -131,6 +138,20 @@ kernfs_create_dir(struct sysfs_dirent *parent, const char *name, void *priv) 
	return kernfs_create_dir_ns(parent, name, priv, NULL);

}



static inline struct sysfs_dirent *

kernfs_create_file_ns(struct sysfs_dirent *parent, const char *name,

		      umode_t mode, loff_t size, const struct kernfs_ops *ops,

		      void *priv, const void *ns)

{

	struct lock_class_key *key = NULL;



#ifdef CONFIG_DEBUG_LOCK_ALLOC

	key = (struct lock_class_key *)&ops->lockdep_key;

#endif

	return kernfs_create_file_ns_key(parent, name, mode, size, ops, priv,

					 ns, key);

}



static inline struct sysfs_dirent *

kernfs_create_file(struct sysfs_dirent *parent, const char *name, umode_t mode,

		   loff_t size, const struct kernfs_ops *ops, void *priv)

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