Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751353AbaANIWz (ORCPT ); Tue, 14 Jan 2014 03:22:55 -0500 Received: from mx1.redhat.com ([209.132.183.28]:63621 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750906AbaANIWy (ORCPT ); Tue, 14 Jan 2014 03:22:54 -0500 Date: Tue, 14 Jan 2014 16:23:23 +0800 From: Dave Young To: wim@iguana.be Cc: dzickus@redhat.com, bhe@redhat.com, vgoyal@redhat.com, linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] watchdog: add a parameter for stop wdt before register Message-ID: <20140114082323.GA4485@dhcp-16-126.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In kdump kernel watchdog could interrupt vmcore capturing because we have no way to disable/stop it while crashing happens. Add a module parameter stop_before_register so watchdog can be stopped before register in driver loading path. Thus we can try to load the watchdog driver as early as possible in kdump kernel to ensure vmcore capturing. Don Zickus mentioned that there's the case that bios start the watchdog and it is expected that the kernel keep the watchdog alive. To address this case I added the module parameter which is false by default so it will stop the watchdog only when user provice kernel cmdline "watchdog.stop_before_register=1". Signed-off-by: Dave Young --- drivers/watchdog/watchdog_core.c | 6 ++++++ 1 file changed, 6 insertions(+) --- linux.orig/drivers/watchdog/watchdog_core.c +++ linux/drivers/watchdog/watchdog_core.c @@ -42,6 +42,7 @@ static DEFINE_IDA(watchdog_ida); static struct class *watchdog_class; +static bool stop_before_register; static void watchdog_check_min_max_timeout(struct watchdog_device *wdd) { @@ -119,6 +120,9 @@ int watchdog_register_device(struct watc if (wdd->ops->start == NULL || wdd->ops->stop == NULL) return -EINVAL; + if (stop_before_register) + wdd->ops->stop(wdd); + watchdog_check_min_max_timeout(wdd); /* @@ -220,6 +224,8 @@ static void __exit watchdog_exit(void) subsys_initcall(watchdog_init); module_exit(watchdog_exit); +module_param(stop_before_register, bool, 0644); + MODULE_AUTHOR("Alan Cox "); MODULE_AUTHOR("Wim Van Sebroeck "); MODULE_DESCRIPTION("WatchDog Timer Driver Core"); -- 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/