From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934719AbXHLLt5 (ORCPT ); Sun, 12 Aug 2007 07:49:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934459AbXHLLtm (ORCPT ); Sun, 12 Aug 2007 07:49:42 -0400 Received: from 1wt.eu ([62.212.114.60]:1666 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934398AbXHLLte (ORCPT ); Sun, 12 Aug 2007 07:49:34 -0400 Date: Sun, 12 Aug 2007 13:47:26 +0200 From: Willy Tarreau To: Jason Uhlenkott Cc: linux-kernel@vger.kernel.org, stable@kernel.org, Thomas Gleixner , john stultz , Dave Jones , Ingo Molnar , Vincent Fortier , Chris Wright , Greg Kroah-Hartman Subject: Re: [2.6.20.16 review 27/28] NTP: remove clock_was_set() call to prevent deadlock Message-ID: <20070812114726.GB29161@1wt.eu> References: <20070811184752.%N@1wt.eu> <20070811184857.%N@1wt.eu> <20070812111558.GA18647@aurum.uhlenkott.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070812111558.GA18647@aurum.uhlenkott.net> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Aug 12, 2007 at 04:15:58AM -0700, Jason Uhlenkott wrote: > On Sat, Aug 11, 2007 at 21:48:19 +0200, Willy Tarreau wrote: > > The clock_was_set() call in seconds_overflow() which happens only when > > leap seconds are inserted / deleted is wrong in two aspects: > > > > 1. it results in a call to on_each_cpu() with interrupts disabled > > 2. it is potential deadlock source vs. call_lock in smp_call_function() > > clock_was_set() is a no-op in 2.6.20, so this one looks unnecessary > (but harmless). Thankfully the "hang every Linux box on the planet > simultaneously" regression (okay, that's *slight* hyperbole) was > limited to 2.6.21. OK, patch removed. Thanks for your help, Willy