Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261898AbUJZC5E (ORCPT ); Mon, 25 Oct 2004 22:57:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262066AbUJZC4h (ORCPT ); Mon, 25 Oct 2004 22:56:37 -0400 Received: from sccrmhc12.comcast.net ([204.127.202.56]:5515 "EHLO sccrmhc12.comcast.net") by vger.kernel.org with ESMTP id S261898AbUJZCuG (ORCPT ); Mon, 25 Oct 2004 22:50:06 -0400 Message-ID: <417DBB5A.6020207@acm.org> Date: Mon, 25 Oct 2004 21:50:02 -0500 From: Corey Minyard User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20040913 X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Maciej W. Rozycki" Cc: Andi Kleen , linux-kernel@vger.kernel.org Subject: Re: Race betwen the NMI handler and the RTC clock in practially all kernels II References: <417D2305.3020209@acm.org.suse.lists.linux.kernel> <20041025201758.GG9142@wotan.suse.de> <20041025204144.GA27518@wotan.suse.de> <417D786F.4020101@acm.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 965 Lines: 23 Maciej W. Rozycki wrote: >>And you need a mutex for SMP systems. If one processor is handling an >>NMI, another processor may still be accessing the device. >> >> > Actually this path is meant to be ever accessed by one CPU only (one that >has its LINT1 line enabled), but it may be reached by other ones due to >the NMI watchdog as code does not check if its run by the right processor. >This probably qualifies as a bug. Only the watchdog code of the NMI >handler is expected to run everywhere. > > Yes, only one processor will run through the NMI code, but another processor may be accessing the RTC or something else in CMOS. The mutex will prevent the NMI and the RTC access from conflicting. -Corey - 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/