Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751962Ab2E2ILd (ORCPT ); Tue, 29 May 2012 04:11:33 -0400 Received: from e28smtp07.in.ibm.com ([122.248.162.7]:52849 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751149Ab2E2ILb (ORCPT ); Tue, 29 May 2012 04:11:31 -0400 Message-ID: <4FC48281.4030502@linux.vnet.ibm.com> Date: Tue, 29 May 2012 13:32:09 +0530 From: "Srivatsa S. Bhat" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120424 Thunderbird/12.0 MIME-Version: 1.0 To: Yong Zhang CC: linux-kernel@vger.kernel.org, ralf@linux-mips.org, sshtylyov@mvista.com, david.daney@cavium.com, nikunj@linux.vnet.ibm.com, paulmck@linux.vnet.ibm.com, axboe@kernel.dk, mingo@kernel.org, tglx@linutronix.de, peterz@infradead.org, akpm@linux-foundation.org Subject: Re: [RFC PATCH 00/10] Cleanup ipi_call_lock[_irq]()/ipi_call_unlock[_irq]() References: <1338275765-3217-1-git-send-email-yong.zhang0@gmail.com> In-Reply-To: <1338275765-3217-1-git-send-email-yong.zhang0@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit x-cbid: 12052908-8878-0000-0000-000002B39A3C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2039 Lines: 47 On 05/29/2012 12:45 PM, Yong Zhang wrote: > As discussed with Srivatsa [1], it seems there is no need to keep > ipi_call_[un]lock_irq() when cpu bring-up/down. Because: > > 1) call_function.lock used in smp_call_function_many() is just to protect > call_function.queue and &data->refs, cpu_online_mask is outside of the > lock. And it's not necessary to protect cpu_online_mask, > because data->cpumask is pre-calculate and even if a cpu is brougt up > when calling arch_send_call_function_ipi_mask(), it's harmless because > validation test in generic_smp_call_function_interrupt() will take care > of it. > > 2) For cpu down issue, stop_machine() will guarantee that no concurrent > smp_call_fuction() is processing. > > In short it's more likely that keeping ipi_call_[un]lock() is leftover > before we introduce generic smp helper. This patchset is just to clean > things up. > > [1] http://marc.info/?l=linux-kernel&m=133766786814484&w=2 > > Yong Zhang (10): > hexagon: smp: remove call to ipi_call_lock()/ipi_call_unlock() > mn10300: smp: remove call to ipi_call_lock()/ipi_call_unlock() > parisc: smp: remove call to ipi_call_lock()/ipi_call_unlock() > S390: smp: remove call to ipi_call_lock()/ipi_call_unlock() > tile: smp: remove call to ipi_call_lock()/ipi_call_unlock() > x86: smp: remove call to ipi_call_lock()/ipi_call_unlock() > ia64: smp: remove call to ipi_call_lock_irq()/ipi_call_unlock_irq() > SPARC: smp: remove call to ipi_call_lock_irq()/ipi_call_unlock_irq() > POWERPC: smp: remove call to ipi_call_lock()/ipi_call_unlock() > smp: remove ipi_call_lock[_irq]()/ipi_call_unlock[_irq]() > All patches except the sparc one look good. Acked-by: Srivatsa S. Bhat Regards, Srivatsa S. Bhat -- 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/