From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760749AbYHAWqL (ORCPT ); Fri, 1 Aug 2008 18:46:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760820AbYHAWmJ (ORCPT ); Fri, 1 Aug 2008 18:42:09 -0400 Received: from saraswathi.solana.com ([198.99.130.12]:52161 "EHLO saraswathi.solana.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760797AbYHAWmI (ORCPT ); Fri, 1 Aug 2008 18:42:08 -0400 Date: Fri, 1 Aug 2008 18:41:28 -0400 From: Jeff Dike To: stable@kernel.org Cc: LKML , uml-devel , Nix Subject: [PATCH 6/14] uml: deal with host time going backwards Message-ID: <20080801224128.GA13721@c2.user-mode-linux.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>From b547462b600e9d284f9d40ed558ca2b8904af185 Mon Sep 17 00:00:00 2001 Protection against the host's time going backwards (eg, ntp activity on the host) by keeping track of the time at the last tick and if it's greater than the current time, keep time stopped until the host catches up. Cc: Nix Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/os-Linux/time.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c index bee98f4..dec5678 100644 --- a/arch/um/os-Linux/time.c +++ b/arch/um/os-Linux/time.c @@ -106,6 +106,10 @@ static void deliver_alarm(void) unsigned long long this_tick = os_nsecs(); int one_tick = UM_NSEC_PER_SEC / UM_HZ; + /* Protection against the host's time going backwards */ + if ((last_tick != 0) && (this_tick < last_tick)) + this_tick = last_tick; + if (last_tick == 0) last_tick = this_tick - one_tick; @@ -148,6 +152,9 @@ static int after_sleep_interval(struct timespec *ts) start_usecs = usec; start_usecs -= skew / UM_NSEC_PER_USEC; + if (start_usecs < 0) + start_usecs = 0; + tv = ((struct timeval) { .tv_sec = start_usecs / UM_USEC_PER_SEC, .tv_usec = start_usecs % UM_USEC_PER_SEC }); interval = ((struct itimerval) { { 0, usec }, tv }); -- 1.5.5.1