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authorMatthew Wilcox <willy@infradead.org>2016-12-14 15:08:34 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-14 16:04:10 -0800
commit91d9c05ac6c788531136888d31ef18c6a0ec160f (patch)
tree858de508527dbe571ca87a77d572a38ebf92b55d
parent91b9677c4c1242a3d0afd76d0e91f43808243b92 (diff)
downloadlinux-stericsson-91d9c05ac6c788531136888d31ef18c6a0ec160f.tar.gz
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 <willy@infradead.org> Tested-by: Kirill 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/radix-tree.h14
-rw-r--r--lib/radix-tree.c1
2 files changed, 5 insertions, 10 deletions
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 744486057e9e..d04073ac3a9f 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 60c10361cbfa..8c5911eae5e2 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);
}