Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752555Ab2E2I1z (ORCPT ); Tue, 29 May 2012 04:27:55 -0400 Received: from mail-vb0-f46.google.com ([209.85.212.46]:49386 "EHLO mail-vb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751253Ab2E2I1w (ORCPT ); Tue, 29 May 2012 04:27:52 -0400 Date: Tue, 29 May 2012 16:27:33 +0800 From: Yong Zhang To: "Srivatsa S. Bhat" 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, "David S. Miller" , sparclinux@vger.kernel.org Subject: [UPDATED] [RFC PATCH 08/10] SPARC: smp: remove call to ipi_call_lock_irq()/ipi_call_unlock_irq() Message-ID: <20120529082732.GA4250@zhy> Reply-To: Yong Zhang References: <1338275765-3217-1-git-send-email-yong.zhang0@gmail.com> <1338275765-3217-9-git-send-email-yong.zhang0@gmail.com> <4FC48272.9040904@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <4FC48272.9040904@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2729 Lines: 83 On Tue, May 29, 2012 at 01:31:54PM +0530, Srivatsa S. Bhat wrote: > This looks odd. IRQs must not have been enabled at this point. > Just remove the call to local_irq_enable() that is found a few lines above > this line and then you won't have to add this call to local_irq_disable(). Yeah, have thought about it. But because I was not sure there is special need to enalbe irq that early (don't know much about sparc), I decided to make minor change :) Since we have gotten confirmation from David, I'm sending out the new version. Please check it. Thanks, Yong --- From: Yong Zhang Date: Tue, 29 May 2012 12:56:08 +0800 Subject: [UPDATED] [RFC PATCH 8/10] SPARC: smp: remove call to ipi_call_lock_irq()/ipi_call_unlock_irq() 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. And also delay irq enable to after set_cpu_online(). Signed-off-by: Yong Zhang Cc: "David S. Miller" Cc: sparclinux@vger.kernel.org --- arch/sparc/kernel/smp_64.c | 7 +------ 1 files changed, 1 insertions(+), 6 deletions(-) diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c index f591598..781bcb1 100644 --- a/arch/sparc/kernel/smp_64.c +++ b/arch/sparc/kernel/smp_64.c @@ -103,8 +103,6 @@ void __cpuinit smp_callin(void) if (cheetah_pcache_forced_on) cheetah_enable_pcache(); - local_irq_enable(); - callin_flag = 1; __asm__ __volatile__("membar #Sync\n\t" "flush %%g6" : : : "memory"); @@ -124,9 +122,8 @@ void __cpuinit smp_callin(void) while (!cpumask_test_cpu(cpuid, &smp_commenced_mask)) rmb(); - ipi_call_lock_irq(); set_cpu_online(cpuid, true); - ipi_call_unlock_irq(); + local_irq_enable(); /* idle thread is expected to have preempt disabled */ preempt_disable(); @@ -1308,9 +1305,7 @@ int __cpu_disable(void) mdelay(1); local_irq_disable(); - ipi_call_lock(); set_cpu_online(cpu, false); - ipi_call_unlock(); cpu_map_rebuild(); -- 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/