From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755487Ab2FERgj (ORCPT ); Tue, 5 Jun 2012 13:36:39 -0400 Received: from mail-lb0-f174.google.com ([209.85.217.174]:59747 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755216Ab2FERgh (ORCPT ); Tue, 5 Jun 2012 13:36:37 -0400 Subject: [PATCH BUGFIX] radix-tree: fix contiguous iterator To: Linus Torvalds From: Konstantin Khlebnikov Cc: Andrew Morton , Hugh Dickins , linux-kernel@vger.kernel.org, stable Date: Tue, 05 Jun 2012 21:36:33 +0400 Message-ID: <20120605173633.27150.64995.stgit@zurg> User-Agent: StGit/0.15 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch fixes bug in macro radix_tree_for_each_contig(). If radix_tree_next_slot() sees NULL in next slot it returns NULL, but following radix_tree_next_chunk() switches iterating into next chunk. As result iterating becomes non-contiguous and breaks vfs "splice" and all its users. Signed-off-by: Konstantin Khlebnikov Reported-and-bisected-by: Hans de Bruin Reported-and-bisected-by: Ondrej Zary Reported-and-bisected-by: Toralf Förster Link: https://lkml.org/lkml/2012/6/5/64 Cc: stable # 3.4.x --- include/linux/radix-tree.h | 5 ++++- lib/radix-tree.c | 3 +++ 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 0d04cd6..ffc444c 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -368,8 +368,11 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags) iter->index++; if (likely(*slot)) return slot; - if (flags & RADIX_TREE_ITER_CONTIG) + if (flags & RADIX_TREE_ITER_CONTIG) { + /* forbid switching to the next chunk */ + iter->next_index = 0; break; + } } } return NULL; diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 86516f5..3ac50dc 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -673,6 +673,9 @@ void **radix_tree_next_chunk(struct radix_tree_root *root, * during iterating; it can be zero only at the beginning. * And we cannot overflow iter->next_index in a single step, * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG. + * + * This condition also used by radix_tree_next_slot() to stop + * contiguous iterating, and forbid swithing to the next chunk. */ index = iter->next_index; if (!index && iter->index)