From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932654Ab2IRCcY (ORCPT ); Mon, 17 Sep 2012 22:32:24 -0400 Received: from e1.ny.us.ibm.com ([32.97.182.141]:36016 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932436Ab2IRCcV (ORCPT ); Mon, 17 Sep 2012 22:32:21 -0400 From: John Stultz To: stable@vger.kernel.org Cc: John Stultz , Prarit Bhargava , Ingo Molnar , Thomas Gleixner , Linux Kernel Subject: [PATCH 2/3] 2.6.32.y: time: Avoid making adjustments if we haven't accumulated anything Date: Mon, 17 Sep 2012 22:32:09 -0400 Message-Id: <1347935530-33767-3-git-send-email-john.stultz@linaro.org> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1347935530-33767-1-git-send-email-john.stultz@linaro.org> References: <1347935530-33767-1-git-send-email-john.stultz@linaro.org> x-cbid: 12091802-6078-0000-0000-00000FB2424F Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a -stable backport of bf2ac312195155511a0f79325515cbb61929898a If update_wall_time() is called and the current offset isn't large enough to accumulate, avoid re-calling timekeeping_adjust which may change the clock freq and can cause 1ns inconsistencies with CLOCK_REALTIME_COARSE/CLOCK_MONOTONIC_COARSE. Signed-off-by: John Stultz Cc: Prarit Bhargava Cc: Ingo Molnar Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1345595449-34965-5-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner Cc: Linux Kernel Signed-off-by: John Stultz --- kernel/time/timekeeping.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 85d51c4..b451c93 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -807,6 +807,10 @@ void update_wall_time(void) #else offset = timekeeper.cycle_interval; #endif + /* Check if there's really nothing to do */ + if (offset < timekeeper.cycle_interval) + return; + timekeeper.xtime_nsec = (s64)xtime.tv_nsec << timekeeper.shift; /* normally this loop will run just once, however in the -- 1.7.9.5