From 91d9c05ac6c788531136888d31ef18c6a0ec160f Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Wed, 14 Dec 2016 15:08:34 -0800 Subject: 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: Matthew Wilcox Tested-by: Kirill A. Shutemov Cc: Konstantin Khlebnikov Cc: Ross Zwisler Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/radix-tree.h | 14 ++++---------- lib/radix-tree.c | 1 + 2 files changed, 5 insertions(+), 10 deletions(-) diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 7444860..d04073a 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -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; - }; - /* Used when freeing node */ - struct rcu_head rcu_head; + struct list_head private_list; /* For tree user */ + struct rcu_head rcu_head; /* Used when freeing node */ }; - /* 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]; }; diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 60c1036..8c5911e 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -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); } -- cgit v1.1