From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753865AbZBDCoq (ORCPT ); Tue, 3 Feb 2009 21:44:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751821AbZBDCoh (ORCPT ); Tue, 3 Feb 2009 21:44:37 -0500 Received: from ozlabs.org ([203.10.76.45]:40509 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751244AbZBDCog (ORCPT ); Tue, 3 Feb 2009 21:44:36 -0500 From: Rusty Russell To: Andrew Morton Subject: Re: [PATCH 2/3] work_on_cpu: Use our own workqueue. Date: Wed, 4 Feb 2009 13:14:31 +1030 User-Agent: KMail/1.11.0 (Linux/2.6.27-11-generic; KDE/4.2.0; i686; ; ) Cc: travis@sgi.com, mingo@redhat.com, davej@redhat.com, cpufreq@vger.kernel.org, linux-kernel@vger.kernel.org References: <20090116191108.135927000@polaris-admin.engr.sgi.com> <200902022305.51344.rusty@rustcorp.com.au> <20090202200649.c1af2fd1.akpm@linux-foundation.org> In-Reply-To: <20090202200649.c1af2fd1.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200902041314.32277.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 03 February 2009 14:36:49 Andrew Morton wrote: > But as you say, rdmsr_on_cpu() is easy to do, using > smp_call_function_single(). Then we can easily convert all other > work_on_cpu() callers to smp_call_function_single() and zap > work_on_cpu(). The best outcome, methinks. grepping for set_cpus_allowed reveals the following users in the first third (when I got tired of it): File Function Context Calls powerpc/kernel/smp.c smp_cpus_done kernel_init smp_ops->setup_cpu() x86/.../speedstep-ich.c _speedstep_get cpufreq speedstep_get_processor_frequency() x86/.../powernow-k8.c check_supported_cpu cpufreq cpuid_*() x86/.../powernow-k8.c powernowk8_target cpufreq mutex_lock, etc x86/.../powernow-k8.c powernowk8_cpu_init boot/hotplg rdmsr,wrmsr x86/.../powernow-k8.c powernowk8_get cpufreq rdmsr x86/.../speedstep-centrino.c get_cur_freq cpufreq rdmsr x86/.../speedstep-centrino.c centrino_target cpufreq rdmsr,wrmsr x86/kernel/reboot.c nativ..._shutdown sys_reboot misc x86/.../microcode_core.c do_microcode_update sys_write microcode_ops->request_microcode_user x86/.../microcode_core.c reload_store sys_write mutex_lock, etc Some of these (reboot) we don't care what they do to cpumask. Some are poor style, but not critical (boot time). Some can use smp_call_function. But there are some which should *not* be frobbing their cpus_allowed, and really do seem to want a user context. I think you're right though: smp_call_function_single (or neat wrappers) where possible, work_on_cpu which can fail for the others, and we'll just have to plumb in the error returns. I'll start the patchstream for 2.6.30. Thanks, Rusty.