From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753163AbdHXNmO (ORCPT ); Thu, 24 Aug 2017 09:42:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56518 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752974AbdHXNmK (ORCPT ); Thu, 24 Aug 2017 09:42:10 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 3C5BD81DE9 Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=prarit@redhat.com From: Prarit Bhargava To: linux-kernel@vger.kernel.org Cc: Prarit Bhargava , John Stultz , Thomas Gleixner , Stephen Boyd Subject: [PATCH 1/2 v8] time: Make fast functions return 0 before timekeeping is initialized Date: Thu, 24 Aug 2017 09:42:01 -0400 Message-Id: <1503582122-22841-2-git-send-email-prarit@redhat.com> In-Reply-To: <1503582122-22841-1-git-send-email-prarit@redhat.com> References: <1503582122-22841-1-git-send-email-prarit@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Thu, 24 Aug 2017 13:42:10 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org printk timestamps will be extended to include mono and boot time by using the fast timekeeping functions ktime_get_mono|boot_fast_ns() functions. The functions can return garbage before timekeeping is initialized resulting in garbage timestamps. The fast time functions must return 0 before timekeeping is initialized. Signed-off-by: Prarit Bhargava Suggested-by: Peter Zijlstra Cc: John Stultz Cc: Thomas Gleixner Cc: Stephen Boyd --- kernel/time/timekeeping.c | 47 +++++++++++++++++++++++++++++++++-------------- 1 file changed, 33 insertions(+), 14 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index cedafa008de5..d111039e0245 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -60,8 +60,39 @@ struct tk_fast { struct tk_read_base base[2]; }; -static struct tk_fast tk_fast_mono ____cacheline_aligned; -static struct tk_fast tk_fast_raw ____cacheline_aligned; +/* Suspend-time cycles value for halted fast timekeeper. */ +static u64 cycles_at_suspend; + +static u64 dummy_clock_read(struct clocksource *cs) +{ + return cycles_at_suspend; +} + +static struct clocksource dummy_clock = { + .read = dummy_clock_read, +}; + +static struct tk_fast tk_fast_mono ____cacheline_aligned = { + .base = { + (struct tk_read_base){ + .clock = &dummy_clock, + }, + (struct tk_read_base){ + .clock = &dummy_clock, + }, + }, +}; + +static struct tk_fast tk_fast_raw ____cacheline_aligned = { + .base = { + (struct tk_read_base){ + .clock = &dummy_clock, + }, + (struct tk_read_base){ + .clock = &dummy_clock, + }, + }, +}; /* flag for if timekeeping is suspended */ int __read_mostly timekeeping_suspended; @@ -477,18 +508,6 @@ u64 notrace ktime_get_boot_fast_ns(void) } EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns); -/* Suspend-time cycles value for halted fast timekeeper. */ -static u64 cycles_at_suspend; - -static u64 dummy_clock_read(struct clocksource *cs) -{ - return cycles_at_suspend; -} - -static struct clocksource dummy_clock = { - .read = dummy_clock_read, -}; - /** * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource. * @tk: Timekeeper to snapshot. -- 1.8.5.5