From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965759AbdIYTW0 (ORCPT ); Mon, 25 Sep 2017 15:22:26 -0400 Received: from terminus.zytor.com ([65.50.211.136]:49479 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965005AbdIYTWZ (ORCPT ); Mon, 25 Sep 2017 15:22:25 -0400 Date: Mon, 25 Sep 2017 12:18:44 -0700 From: tip-bot for Prarit Bhargava Message-ID: Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org, prarit@redhat.com, sboyd@codeaurora.org, hpa@zytor.com, mingo@kernel.org, john.stultz@linaro.org, peterz@infradead.org Reply-To: john.stultz@linaro.org, peterz@infradead.org, hpa@zytor.com, sboyd@codeaurora.org, mingo@kernel.org, linux-kernel@vger.kernel.org, prarit@redhat.com, tglx@linutronix.de In-Reply-To: <1503922914-10660-2-git-send-email-prarit@redhat.com> References: <1503922914-10660-2-git-send-email-prarit@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/printk] timekeeping: Make fast accessors return 0 before timekeeping is initialized Git-Commit-ID: 5df32107f609c1f621bcdac0a685c23677ef671e X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 5df32107f609c1f621bcdac0a685c23677ef671e Gitweb: http://git.kernel.org/tip/5df32107f609c1f621bcdac0a685c23677ef671e Author: Prarit Bhargava AuthorDate: Mon, 28 Aug 2017 08:21:53 -0400 Committer: Thomas Gleixner CommitDate: Mon, 25 Sep 2017 21:05:59 +0200 timekeeping: Make fast accessors return 0 before timekeeping is initialized printk timestamps will be extended to include mono and boot time by using the fast timekeeping accessors ktime_get_mono|boot_fast_ns(). The functions can return garbage before timekeeping is initialized resulting in garbage timestamps. Initialize the fast timekeepers with dummy clocks which guarantee a 0 readout up to timekeeping_init(). Suggested-by: Peter Zijlstra Signed-off-by: Prarit Bhargava Signed-off-by: Thomas Gleixner Cc: Stephen Boyd Cc: John Stultz Link: http://lkml.kernel.org/r/1503922914-10660-2-git-send-email-prarit@redhat.com --- kernel/time/timekeeping.c | 35 +++++++++++++++++++++-------------- 1 file changed, 21 insertions(+), 14 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 2cafb49..6a92794 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -60,8 +60,27 @@ 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[0] = { .clock = &dummy_clock, }, + .base[1] = { .clock = &dummy_clock, }, +}; + +static struct tk_fast tk_fast_raw ____cacheline_aligned = { + .base[0] = { .clock = &dummy_clock, }, + .base[1] = { .clock = &dummy_clock, }, +}; /* flag for if timekeeping is suspended */ int __read_mostly timekeeping_suspended; @@ -477,18 +496,6 @@ 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.