Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753616AbaBDA6i (ORCPT ); Mon, 3 Feb 2014 19:58:38 -0500 Received: from zene.cmpxchg.org ([85.214.230.12]:56931 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751864AbaBDA6g (ORCPT ); Mon, 3 Feb 2014 19:58:36 -0500 From: Johannes Weiner To: Andrew Morton Cc: Andi Kleen , Andrea Arcangeli , Bob Liu , Christoph Hellwig , Dave Chinner , Greg Thelen , Hugh Dickins , Jan Kara , KOSAKI Motohiro , Luigi Semenzato , Mel Gorman , Metin Doslu , Michel Lespinasse , Minchan Kim , Ozgun Erdogan , Peter Zijlstra , Rik van Riel , Roman Gushchin , Ryan Mallon , Tejun Heo , Vlastimil Babka , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [patch 03/10] lib: radix-tree: radix_tree_delete_item() Date: Mon, 3 Feb 2014 19:53:35 -0500 Message-Id: <1391475222-1169-4-git-send-email-hannes@cmpxchg.org> X-Mailer: git-send-email 1.8.5.3 In-Reply-To: <1391475222-1169-1-git-send-email-hannes@cmpxchg.org> References: <1391475222-1169-1-git-send-email-hannes@cmpxchg.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Provide a function that does not just delete an entry at a given index, but also allows passing in an expected item. Delete only if that item is still located at the specified index. This is handy when lockless tree traversals want to delete entries as well because they don't have to do an second, locked lookup to verify the slot has not changed under them before deleting the entry. Signed-off-by: Johannes Weiner Reviewed-by: Minchan Kim Reviewed-by: Rik van Riel --- include/linux/radix-tree.h | 1 + lib/radix-tree.c | 31 +++++++++++++++++++++++++++---- 2 files changed, 28 insertions(+), 4 deletions(-) diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 403940787be1..1bf0a9c388d9 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -219,6 +219,7 @@ static inline void radix_tree_replace_slot(void **pslot, void *item) int radix_tree_insert(struct radix_tree_root *, unsigned long, void *); void *radix_tree_lookup(struct radix_tree_root *, unsigned long); void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long); +void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *); void *radix_tree_delete(struct radix_tree_root *, unsigned long); unsigned int radix_tree_gang_lookup(struct radix_tree_root *root, void **results, diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 7811ed3b4e70..f442e3243607 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -1335,15 +1335,18 @@ static inline void radix_tree_shrink(struct radix_tree_root *root) } /** - * radix_tree_delete - delete an item from a radix tree + * radix_tree_delete_item - delete an item from a radix tree * @root: radix tree root * @index: index key + * @item: expected item * - * Remove the item at @index from the radix tree rooted at @root. + * Remove @item at @index from the radix tree rooted at @root. * - * Returns the address of the deleted item, or NULL if it was not present. + * Returns the address of the deleted item, or NULL if it was not present + * or the entry at the given @index was not @item. */ -void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) +void *radix_tree_delete_item(struct radix_tree_root *root, + unsigned long index, void *item) { struct radix_tree_node *node = NULL; struct radix_tree_node *slot = NULL; @@ -1378,6 +1381,11 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) if (slot == NULL) goto out; + if (item && slot != item) { + slot = NULL; + goto out; + } + /* * Clear all tags associated with the item to be deleted. * This way of doing it would be inefficient, but seldom is any set. @@ -1422,6 +1430,21 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) out: return slot; } +EXPORT_SYMBOL(radix_tree_delete_item); + +/** + * radix_tree_delete - delete an item from a radix tree + * @root: radix tree root + * @index: index key + * + * Remove the item at @index from the radix tree rooted at @root. + * + * Returns the address of the deleted item, or NULL if it was not present. + */ +void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) +{ + return radix_tree_delete_item(root, index, NULL); +} EXPORT_SYMBOL(radix_tree_delete); /** -- 1.8.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/