Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753382Ab2E2HRd (ORCPT ); Tue, 29 May 2012 03:17:33 -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 S1753274Ab2E2HRb (ORCPT ); Tue, 29 May 2012 03:17:31 -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, Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Konrad Rzeszutek Wilk , Jeremy Fitzhardinge Subject: [RFC PATCH 06/10] x86: smp: remove call to ipi_call_lock()/ipi_call_unlock() Date: Tue, 29 May 2012 15:16:01 +0800 Message-Id: <1338275765-3217-7-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: 2648 Lines: 74 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: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: Konrad Rzeszutek Wilk Cc: Jeremy Fitzhardinge --- arch/x86/kernel/smpboot.c | 9 --------- arch/x86/xen/smp.c | 2 -- 2 files changed, 0 insertions(+), 11 deletions(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 433529e..bfbe30e 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -253,22 +253,13 @@ notrace static void __cpuinit start_secondary(void *unused) check_tsc_sync_target(); /* - * 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(). - * * We need to hold vector_lock so there the set of online cpus * does not change while we are assigning vectors to cpus. Holding * this lock ensures we don't half assign or remove an irq from a cpu. */ - ipi_call_lock(); lock_vector_lock(); set_cpu_online(smp_processor_id(), true); unlock_vector_lock(); - ipi_call_unlock(); per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE; x86_platform.nmi_init(); diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index afb250d..f58dca7 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -80,9 +80,7 @@ static void __cpuinit cpu_bringup(void) notify_cpu_starting(cpu); - ipi_call_lock(); set_cpu_online(cpu, true); - ipi_call_unlock(); this_cpu_write(cpu_state, CPU_ONLINE); -- 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/