From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764072AbYHEUPy (ORCPT ); Tue, 5 Aug 2008 16:15:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763585AbYHEUOb (ORCPT ); Tue, 5 Aug 2008 16:14:31 -0400 Received: from saraswathi.solana.com ([198.99.130.12]:48072 "EHLO saraswathi.solana.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758710AbYHEUOa (ORCPT ); Tue, 5 Aug 2008 16:14:30 -0400 Date: Tue, 5 Aug 2008 16:14:06 -0400 From: Jeff Dike To: stable@kernel.org Cc: LKML , uml-devel Subject: [PATCH 6/14] uml: deal with host time going backwards Message-ID: <20080805201406.GA11786@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 06e1e4ffbd1932e288839b3140cda6b8141eb684 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