Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752302Ab2E2ILf (ORCPT ); Tue, 29 May 2012 04:11:35 -0400 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:48409 "EHLO e28smtp08.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751222Ab2E2ILb (ORCPT ); Tue, 29 May 2012 04:11:31 -0400 Message-ID: <4FC48272.9040904@linux.vnet.ibm.com> Date: Tue, 29 May 2012 13:31:54 +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, "David S. Miller" , sparclinux@vger.kernel.org Subject: Re: [PATCH 08/10] SPARC: smp: remove call to ipi_call_lock_irq()/ipi_call_unlock_irq() References: <1338275765-3217-1-git-send-email-yong.zhang0@gmail.com> <1338275765-3217-9-git-send-email-yong.zhang0@gmail.com> In-Reply-To: <1338275765-3217-9-git-send-email-yong.zhang0@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit x-cbid: 12052908-2000-0000-0000-000007BB60C7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2109 Lines: 67 On 05/29/2012 12:46 PM, Yong Zhang wrote: > 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: "David S. Miller" > Cc: sparclinux@vger.kernel.org > --- > arch/sparc/kernel/smp_64.c | 6 ++---- > 1 files changed, 2 insertions(+), 4 deletions(-) > > diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c > index f591598..60e745c 100644 > --- a/arch/sparc/kernel/smp_64.c > +++ b/arch/sparc/kernel/smp_64.c > @@ -124,9 +124,9 @@ void __cpuinit smp_callin(void) > while (!cpumask_test_cpu(cpuid, &smp_commenced_mask)) > rmb(); > > - ipi_call_lock_irq(); > + local_irq_disable(); 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(). > set_cpu_online(cpuid, true); > - ipi_call_unlock_irq(); > + local_irq_enable(); > > /* idle thread is expected to have preempt disabled */ > preempt_disable(); > @@ -1308,9 +1308,7 @@ int __cpu_disable(void) > mdelay(1); > local_irq_disable(); > > - ipi_call_lock(); > set_cpu_online(cpu, false); > - ipi_call_unlock(); > > cpu_map_rebuild(); > 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/