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=-13.7 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 25E7FC71156 for ; Tue, 1 Dec 2020 16:01:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3701206B7 for ; Tue, 1 Dec 2020 16:01:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392016AbgLAQBa (ORCPT ); Tue, 1 Dec 2020 11:01:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:42710 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391653AbgLAQB2 (ORCPT ); Tue, 1 Dec 2020 11:01:28 -0500 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 97B512223F; Tue, 1 Dec 2020 16:00:07 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.94) (envelope-from ) id 1kk84T-002R6U-Su; Tue, 01 Dec 2020 11:00:05 -0500 Message-ID: <20201201160005.780999537@goodmis.org> User-Agent: quilt/0.66 Date: Tue, 01 Dec 2020 10:58:40 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , stable@vger.kernel.org, "J. Avila" , Daniel Mentz , Will McVicker Subject: [for-linus][PATCH 05/12] ring-buffer: Update write stamp with the correct ts References: <20201201155835.647858317@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" The write stamp, used to calculate deltas between events, was updated with the stale "ts" value in the "info" structure, and not with the updated "ts" variable. This caused the deltas between events to be inaccurate, and when crossing into a new sub buffer, had time go backwards. Link: https://lkml.kernel.org/r/20201124223917.795844-1-elavila@google.com Cc: stable@vger.kernel.org Fixes: a389d86f7fd09 ("ring-buffer: Have nested events still record running time stamp") Reported-by: "J. Avila" Tested-by: Daniel Mentz Tested-by: Will McVicker Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index dc83b3fa9fe7..bccaf88d3706 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -3291,7 +3291,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, /* Nothing came after this event between C and E */ info->delta = ts - info->after; (void)rb_time_cmpxchg(&cpu_buffer->write_stamp, - info->after, info->ts); + info->after, ts); info->ts = ts; } else { /* -- 2.28.0