From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D5A2C43441 for ; Fri, 16 Nov 2018 08:22:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D26A620869 for ; Fri, 16 Nov 2018 08:22:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D26A620869 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-btrfs-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727502AbeKPSdp (ORCPT ); Fri, 16 Nov 2018 13:33:45 -0500 Received: from mx2.suse.de ([195.135.220.15]:50024 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727405AbeKPSdp (ORCPT ); Fri, 16 Nov 2018 13:33:45 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id DBB98ADA9 for ; Fri, 16 Nov 2018 08:22:25 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH v1.1 7/9] btrfs-progs: Fix Wmaybe-uninitialized warning Date: Fri, 16 Nov 2018 16:22:22 +0800 Message-Id: <20181116082222.15563-1-wqu@suse.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181116075426.4142-8-wqu@suse.com> References: <20181116075426.4142-8-wqu@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org GCC 8.2.1 will report the following warning with "make W=1": ctree.c: In function 'btrfs_next_sibling_tree_block': ctree.c:2990:21: warning: 'slot' may be used uninitialized in this function [-Wmaybe-uninitialized] path->slots[level] = slot; ~~~~~~~~~~~~~~~~~~~^~~~~~ The culprit is the following code: int slot; << Not initialized int level = path->lowest_level + 1; BUG_ON(path->lowest_level + 1 >= BTRFS_MAX_LEVEL); while(level < BTRFS_MAX_LEVEL) { slot = path->slots[level] + 1; ^^^^^^ but we initialize @slot here. ... } path->slots[level] = slot; Again, it's the stupid compiler needs some hint for the fact that we will always enter the while loop for at least once, thus @slot should always be initialized. Fix it by assign level after the BUG_ON(), so the stupid compiler knows we will always go into the while loop. Signed-off-by: Qu Wenruo --- changelog: v1.1: Better commit message, with the original warning report and how compiler thinks this could be a problem. --- ctree.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/ctree.c b/ctree.c index 46e2ccedc0bf..9c9cb0dfdbf2 100644 --- a/ctree.c +++ b/ctree.c @@ -2961,11 +2961,12 @@ int btrfs_next_sibling_tree_block(struct btrfs_fs_info *fs_info, struct btrfs_path *path) { int slot; - int level = path->lowest_level + 1; + int level; struct extent_buffer *c; struct extent_buffer *next = NULL; BUG_ON(path->lowest_level + 1 >= BTRFS_MAX_LEVEL); + level = path->lowest_level + 1; while(level < BTRFS_MAX_LEVEL) { if (!path->nodes[level]) return 1; -- 2.19.1