Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753359Ab2E2HRU (ORCPT ); Tue, 29 May 2012 03:17:20 -0400 Received: from mail-vb0-f46.google.com ([209.85.212.46]:57666 "EHLO mail-vb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751938Ab2E2HRS (ORCPT ); Tue, 29 May 2012 03:17:18 -0400 From: Yong Zhang To: linux-kernel@vger.kernel.org Cc: 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, srivatsa.bhat@linux.vnet.ibm.com, Chris Metcalf Subject: [RFC PATCH 05/10] tile: smp: remove call to ipi_call_lock()/ipi_call_unlock() Date: Tue, 29 May 2012 15:16:00 +0800 Message-Id: <1338275765-3217-6-git-send-email-yong.zhang0@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1338275765-3217-1-git-send-email-yong.zhang0@gmail.com> References: <1338275765-3217-1-git-send-email-yong.zhang0@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1836 Lines: 49 From: Yong Zhang 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. Signed-off-by: Yong Zhang Cc: Chris Metcalf --- arch/tile/kernel/smpboot.c | 10 ---------- 1 files changed, 0 insertions(+), 10 deletions(-) diff --git a/arch/tile/kernel/smpboot.c b/arch/tile/kernel/smpboot.c index 84873fb..e686c5a 100644 --- a/arch/tile/kernel/smpboot.c +++ b/arch/tile/kernel/smpboot.c @@ -198,17 +198,7 @@ void __cpuinit online_secondary(void) notify_cpu_starting(smp_processor_id()); - /* - * We need to hold call_lock, so there is no inconsistency - * between the time smp_call_function() determines number of - * IPI recipients, and the time when the determination is made - * for which cpus receive the IPI. Holding this - * lock helps us to not include this cpu in a currently in progress - * smp_call_function(). - */ - ipi_call_lock(); set_cpu_online(smp_processor_id(), 1); - ipi_call_unlock(); __get_cpu_var(cpu_state) = CPU_ONLINE; /* Set up tile-specific state for this cpu. */ -- 1.7.5.4 -- 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/