Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751583AbaJYSbG (ORCPT ); Sat, 25 Oct 2014 14:31:06 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:33066 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751220AbaJYSbD (ORCPT ); Sat, 25 Oct 2014 14:31:03 -0400 From: HuKeping To: CC: , , , , , , Subject: [PATCH] ARM: kexec: Fix validating CPU hotplug support Date: Sat, 25 Oct 2014 17:20:55 +0800 Message-ID: <1414228855-40739-1-git-send-email-hukeping@huawei.com> X-Mailer: git-send-email 1.8.5.5 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.197.247] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Due to commit:2103f6cba61a8b8bea3fc1b63661d830a2125e76, there is a hotplug checking in machine_kexec_prepare(), but it will lead a failure when loading the crash-kernel in some cases. Kexec utility can load the crash kernel by two ways: 1. kexec -l kernel-image --append=command-line-options --initrd=initrd-image 2. kexec -p kernel-image --append=command-line-options --initrd=initrd-image In case #1, it's ok to do the hotplug checking things, for it will cut off cpus in _cpu_down() later when command "kexec -e" be sended, function _cpu_down() needs the support of cpu hotplug. In case #2, it is no need to do the checking, because we actually do not shut the cpus down, but just keep them invoking cpu_relax(), the whole routing has no business with cpu cutting off. That means, even if the CONFIG_HOTPLUG_CPU was not selected, it can also load and reboot the crash-kernel successfully if we use "kexec -p ..." and then a crash came to trigger the kexec. Prior to this patch, if the first kernel is not support the CPU hotplug, we can not use kexec utility. Signed-off-by: Hu Keping --- arch/arm/kernel/machine_kexec.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c index 8cf0996..1e5620f 100644 --- a/arch/arm/kernel/machine_kexec.c +++ b/arch/arm/kernel/machine_kexec.c @@ -41,12 +41,20 @@ int machine_kexec_prepare(struct kimage *image) int i, err; /* - * Validate that if the current HW supports SMP, then the SW supports - * and implements CPU hotplug for the current HW. If not, we won't be - * able to kexec reliably, so fail the prepare operation. + * When it is a * crash * triggered the kexec, we do not really shut the + * cpus down but just let them keep invoking cpu_relax(), so there is no need + * to do the hotplug checking things. */ - if (num_possible_cpus() > 1 && !platform_can_cpu_hotplug()) - return -EINVAL; + if (image->type != KEXEC_TYPE_CRASH) + { + /* + * Validate that if the current HW supports SMP, then the SW supports + * and implements CPU hotplug for the current HW. If not, we won't be + * able to kexec reliably, so fail the prepare operation. + */ + if (num_possible_cpus() > 1 && !platform_can_cpu_hotplug()) + return -EINVAL; + } /* * No segment at default ATAGs address. try to locate -- 1.8.5.5 -- 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/