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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 A7FD0C11F66 for ; Wed, 30 Jun 2021 23:18:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E9D761467 for ; Wed, 30 Jun 2021 23:18:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236551AbhF3XVE (ORCPT ); Wed, 30 Jun 2021 19:21:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:38918 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235704AbhF3XUx (ORCPT ); Wed, 30 Jun 2021 19:20:53 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 53DC96146D; Wed, 30 Jun 2021 23:18:23 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.94.2) (envelope-from ) id 1lyjTK-000ZDI-CI; Wed, 30 Jun 2021 19:18:22 -0400 Message-ID: <20210630231822.219090027@goodmis.org> User-Agent: quilt/0.66 Date: Wed, 30 Jun 2021 19:18:00 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Ingo Molnar , Daniel Bristot de Oliveira , Dan Carpenter Subject: [for-next][PATCH 2/5] trace/osnoise: Make noise variable s64 in run_osnoise() References: <20210630231758.861158022@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Bristot de Oliveira Dab Carpenter reported that: The patch bce29ac9ce0b: "trace: Add osnoise tracer" from Jun 22, 2021, leads to the following static checker warning: kernel/trace/trace_osnoise.c:1103 run_osnoise() warn: unsigned 'noise' is never less than zero. In this part of the code: 1100 /* 1101 * This shouldn't happen. 1102 */ 1103 if (noise < 0) { ^^^^^^^^^ 1104 osnoise_taint("negative noise!"); 1105 goto out; 1106 } 1107 And the static checker is right because 'noise' is u64. Make noise s64 and keep the check. It is important to check if the time read is behaving correctly - so we can trust the results. I also re-arranged some variable declarations. Link: https://lkml.kernel.org/r/acd7cd6e7d56b798a298c3bc8139a390b3c4ab52.1624986368.git.bristot@redhat.com Cc: Ingo Molnar Cc: Daniel Bristot de Oliveira Cc: Dan Carpenter Cc: linux-kernel@vger.kernel.org Fixes: bce29ac9ce0b ("trace: Add osnoise tracer") Reported-by: Dan Carpenter Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_osnoise.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 085a83de98ad..cc1faca1a620 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -1042,15 +1042,16 @@ static void osnoise_stop_tracing(void) static int run_osnoise(void) { struct osnoise_variables *osn_var = this_cpu_osn_var(); - u64 noise = 0, sum_noise = 0, max_noise = 0; struct trace_array *tr = osnoise_trace; u64 start, sample, last_sample; u64 last_int_count, int_count; + s64 noise = 0, max_noise = 0; s64 total, last_total = 0; struct osnoise_sample s; unsigned int threshold; - int hw_count = 0; u64 runtime, stop_in; + u64 sum_noise = 0; + int hw_count = 0; int ret = -1; /* -- 2.30.2