Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754660AbaDNJxv (ORCPT ); Mon, 14 Apr 2014 05:53:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60173 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751301AbaDNJwn (ORCPT ); Mon, 14 Apr 2014 05:52:43 -0400 Date: Mon, 14 Apr 2014 11:52:10 +0200 From: Igor Mammedov To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, bp@suse.de, paul.gortmaker@windriver.com, JBeulich@suse.com, prarit@redhat.com, drjones@redhat.com, toshi.kani@hp.com, riel@redhat.com, gong.chen@linux.intel.com, andi@firstfloor.org, lenb@kernel.org, rjw@rjwysocki.net, linux-acpi@vger.kernel.org Subject: Re: [PATCH v3 1/5] x86: initialize secondary CPU only if master CPU will wait for it Message-ID: <20140414115210.51193098@thinkpad> In-Reply-To: <20140414091600.GA19771@gmail.com> References: <1397150061-29735-1-git-send-email-imammedo@redhat.com> <1397150061-29735-2-git-send-email-imammedo@redhat.com> <20140414091600.GA19771@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 14 Apr 2014 11:16:00 +0200 Ingo Molnar wrote: > > * Igor Mammedov wrote: > > > /* > > + * wait for ACK from master CPU before continuing > > + * with AP initialization > > + */ > > + cpumask_set_cpu(cpu, cpu_initialized_mask); > > + while (!cpumask_test_cpu(cpu, cpu_callout_mask)) > > + cpu_relax(); > > > + /* > > + * wait for ACK from master CPU before continuing > > + * with AP initialization > > + */ > > + cpumask_set_cpu(cpu, cpu_initialized_mask); > > + while (!cpumask_test_cpu(cpu, cpu_callout_mask)) > > + cpu_relax(); > > That repetitive pattern could be stuck into a properly named helper > inline function. sure > (Also, before the cpumask_set_cpu() we should probably do a WARN_ON() > if the bit is already set.) The reason why there is no any WARN_ON or likes is that printk is quite complicated, takes looks and so on. So it's not safe at this point since CPU could be shot down by any time by INIT/SIPI until it's out of cpu_callout_mask loop. That said it's possible to add WARN_ON in do_boot_cpu() before cpu_initialized_mask is cleared, to achieve the same effect, so I'll stick it there. > > Thanks, > > Ingo -- Regards, Igor -- 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/