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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,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 3DB14C28CF6 for ; Wed, 1 Aug 2018 17:39:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 01FD82083E for ; Wed, 1 Aug 2018 17:39:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 01FD82083E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407482AbeHATZx (ORCPT ); Wed, 1 Aug 2018 15:25:53 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52928 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2436517AbeHATSh (ORCPT ); Wed, 1 Aug 2018 15:18:37 -0400 Received: from localhost (D57E6652.static.ziggozakelijk.nl [213.126.102.82]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 64142DCB; Wed, 1 Aug 2018 16:53:15 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, kbuild test robot , "Steven Rostedt (VMware)" Subject: [PATCH 4.17 012/336] tracing: Quiet gcc warning about maybe unused link variable Date: Wed, 1 Aug 2018 18:45:47 +0200 Message-Id: <20180801165029.407424498@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180801165028.930831994@linuxfoundation.org> References: <20180801165028.930831994@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Steven Rostedt (VMware) commit 2519c1bbe38d7acacc9aacba303ca6f97482ed53 upstream. Commit 57ea2a34adf4 ("tracing/kprobes: Fix trace_probe flags on enable_trace_kprobe() failure") added an if statement that depends on another if statement that gcc doesn't see will initialize the "link" variable and gives the warning: "warning: 'link' may be used uninitialized in this function" It is really a false positive, but to quiet the warning, and also to make sure that it never actually is used uninitialized, initialize the "link" variable to NULL and add an if (!WARN_ON_ONCE(!link)) where the compiler thinks it could be used uninitialized. Cc: stable@vger.kernel.org Fixes: 57ea2a34adf4 ("tracing/kprobes: Fix trace_probe flags on enable_trace_kprobe() failure") Reported-by: kbuild test robot Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_kprobe.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -400,7 +400,7 @@ static struct trace_kprobe *find_trace_k static int enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file) { - struct event_file_link *link; + struct event_file_link *link = NULL; int ret = 0; if (file) { @@ -426,7 +426,9 @@ enable_trace_kprobe(struct trace_kprobe if (ret) { if (file) { - list_del_rcu(&link->list); + /* Notice the if is true on not WARN() */ + if (!WARN_ON_ONCE(!link)) + list_del_rcu(&link->list); kfree(link); tk->tp.flags &= ~TP_FLAG_TRACE; } else {