Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758967AbYFCTFt (ORCPT ); Tue, 3 Jun 2008 15:05:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758668AbYFCTEW (ORCPT ); Tue, 3 Jun 2008 15:04:22 -0400 Received: from saraswathi.solana.com ([198.99.130.12]:58523 "EHLO saraswathi.solana.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758626AbYFCTEV (ORCPT ); Tue, 3 Jun 2008 15:04:21 -0400 Date: Tue, 3 Jun 2008 15:02:35 -0400 From: Jeff Dike To: Andrew Morton , LKML , uml-devel Cc: Nix Subject: [PATCH 1/6] UML - Deal with host time going backwards Message-ID: <20080603190235.GA9511@c2.user-mode-linux.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1545 Lines: 40 Protection against the host's time going backwards - keep 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 --- arch/um/os-Linux/time.c | 7 +++++++ 1 file changed, 7 insertions(+) Index: linux-2.6-git/arch/um/os-Linux/time.c =================================================================== --- linux-2.6-git.orig/arch/um/os-Linux/time.c 2008-05-14 10:44:02.000000000 -0400 +++ linux-2.6-git/arch/um/os-Linux/time.c 2008-06-02 15:43:53.000000000 -0400 @@ -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 t 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 }); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/