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: 1897551 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork1.kernel.org (Postfix) with ESMTP id 90E843FC64 for ; Wed, 19 Dec 2012 23:48:23 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TlTJk-0001cp-HF; Wed, 19 Dec 2012 23:44:52 +0000 Received: from avon.wwwdotorg.org ([2001:470:1f0f:bd7::2]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TlTJf-0001c7-Hs; Wed, 19 Dec 2012 23:44:48 +0000 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 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20121219_184447_873762_83777730 X-CRM114-Status: GOOD ( 11.92 ) X-Spam-Score: -2.6 (--) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-2.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_PASS SPF: sender matches SPF record -0.7 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: linux-tegra@vger.kernel.org, Will Deacon , kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Stephen Warren X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.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(); }