Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 91d9c05a authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Linus Torvalds
Browse files

radix-tree: move rcu_head into a union with private_list 

I want to be able to reference node->parent after freeing node.

Currently node->parent is in a union with rcu_head, so it is overwritten
when the node is put on the RCU list.  We know that private_list is not
referenced after the node is freed, so it is safe for these two members
to share space.

Link: http://lkml.kernel.org/r/1480369871-5271-50-git-send-email-mawilcox@linuxonhyperv.com


Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
Tested-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 91b9677c

include/linux/radix-tree.h

+4 −10
Original line number Diff line number Diff line
@@ -85,18 +85,12 @@ struct radix_tree_node { 
	unsigned char	offset;		/* Slot offset in parent */

	unsigned char	count;		/* Total entry count */

	unsigned char	exceptional;	/* Exceptional entry count */

	struct radix_tree_node *parent;		/* Used when ascending tree */

	void *private_data;			/* For tree user */

	union {

		struct {

			/* Used when ascending tree */

			struct radix_tree_node *parent;

			/* For tree user */

			void *private_data;

		struct list_head private_list;	/* For tree user */

		struct rcu_head	rcu_head;	/* Used when freeing node */

	};

		/* Used when freeing node */

		struct rcu_head	rcu_head;

	};

	/* For tree user */

	struct list_head private_list;

	void __rcu	*slots[RADIX_TREE_MAP_SIZE];

	unsigned long	tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];

};

lib/radix-tree.c

+1 −0
Original line number Diff line number Diff line
@@ -325,6 +325,7 @@ static void radix_tree_node_rcu_free(struct rcu_head *head) 
		tag_clear(node, i, 0);



	node->slots[0] = NULL;

	INIT_LIST_HEAD(&node->private_list);



	kmem_cache_free(radix_tree_node_cachep, node);

}