From patchwork Wed Dec 19 23:44:41 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Warren X-Patchwork-Id: 207562 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id C10A42C008C for ; Thu, 20 Dec 2012 10:44:48 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751234Ab2LSXor (ORCPT ); Wed, 19 Dec 2012 18:44:47 -0500 Received: from avon.wwwdotorg.org ([70.85.31.133]:42989 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751175Ab2LSXor (ORCPT ); Wed, 19 Dec 2012 18:44:47 -0500 Received: from severn.wwwdotorg.org (unknown [192.168.65.5]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by avon.wwwdotorg.org (Postfix) with ESMTPS id B5E4A6317; Wed, 19 Dec 2012 16:44:57 -0700 (MST) Received: from swarren-lx1.nvidia.com (localhost [127.0.0.1]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by severn.wwwdotorg.org (Postfix) with ESMTPSA id 77BF5E4105; Wed, 19 Dec 2012 16:44:45 -0700 (MST) From: Stephen Warren To: Eric Biederman Cc: kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-tegra@vger.kernel.org, Will Deacon , Stephen Warren Subject: [PATCH] kexec: disable non-boot CPUs Date: Wed, 19 Dec 2012 16:44:41 -0700 Message-Id: <1355960681-32015-1-git-send-email-swarren@wwwdotorg.org> X-Mailer: git-send-email 1.7.10.4 X-NVConfidentiality: public X-Virus-Scanned: clamav-milter 0.96.5 at avon.wwwdotorg.org X-Virus-Status: Clean Sender: linux-tegra-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org From: Stephen Warren Both the regular reboot and shutdown paths do this. It seems reasonable for kexec to work the same way. On the Tegra ARM SoC at least, this change allows kexec to work with SMP enabled. ARM's machine_shutdown() simply puts all CPUs into a loop. If the code of that loop is over-written, the CPUs may crash, and cause the kexec'd kernel not to be able to initialize them. In practice, this causes the kexec'd kernel to hang and/or crash. The intended way to solve this is for ARM machines to provide a cpu_kill SMP operation to e.g. power down the CPUs, or place them in reset. However, at least on Tegra, the implementation of that function would simply be duplicating the hotplug code that already exists, so it seems simpler to just call disable_nonboot_cpus() for the kexec path, just like reboot/shutdown. Signed-off-by: Stephen Warren --- kernel/kexec.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/kexec.c b/kernel/kexec.c index 5e4bd78..6fe74d3 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -1570,6 +1570,7 @@ int kernel_kexec(void) #endif { kernel_restart_prepare(NULL); + disable_nonboot_cpus(); printk(KERN_EMERG "Starting new kernel\n"); machine_shutdown(); }