From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755454AbZA0P3O (ORCPT ); Tue, 27 Jan 2009 10:29:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752311AbZA0P26 (ORCPT ); Tue, 27 Jan 2009 10:28:58 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:41397 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751461AbZA0P25 (ORCPT ); Tue, 27 Jan 2009 10:28:57 -0500 Date: Tue, 27 Jan 2009 16:28:30 +0100 From: Ingo Molnar To: Andrew Morton Cc: Rusty Russell , Mike Travis , Ingo Molnar , Dave Jones , cpufreq@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] work_on_cpu: Use our own workqueue. Message-ID: <20090127152830.GA22373@elte.hu> References: <20090116191108.135927000@polaris-admin.engr.sgi.com> <200901261711.43943.rusty@rustcorp.com.au> <20090125230130.bcdab2e5.akpm@linux-foundation.org> <200901271735.12034.rusty@rustcorp.com.au> <20090126232519.44f2943c.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090126232519.44f2943c.akpm@linux-foundation.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andrew Morton wrote: > > But it's a general comment about fixing a general issue. The > > currently known case is not directly relevent; that it can happen and > > it's restricting the use of this otherwise-general API is. > > I think we should switch acpi-cpufreq to smp_call_function(), revert > this stuff and ban the calling of work_on_cpu() under locks. I agree that do_drv_read()/write() should be converted to smp_function_call() (what it does is atomic: msr or PIO cycles). Then work_on_cpu() can be removed for good, to not lure people into using it. You seem to agree that work_on_cpu() is unfixable so it's far better to offer nothing than to offer such a deceivingly named but fundamentally limited facility. Ingo