From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753897AbbBEUms (ORCPT ); Thu, 5 Feb 2015 15:42:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57221 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753756AbbBEUko (ORCPT ); Thu, 5 Feb 2015 15:40:44 -0500 From: Don Zickus To: LKML Cc: Andrew Morton , Ulrich Obergfell , Don Zickus Subject: [PATCH 1/9] watchdog: new definitions and variables, initialization Date: Thu, 5 Feb 2015 15:40:17 -0500 Message-Id: <1423168825-156238-2-git-send-email-dzickus@redhat.com> In-Reply-To: <1423168825-156238-1-git-send-email-dzickus@redhat.com> References: <1423168825-156238-1-git-send-email-dzickus@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ulrich Obergfell Introduce new definitions and variables to separate the user interface in /proc/sys/kernel from the internal run state of the lockup detectors. The internal run state is represented by two bits in a new variable that is named 'watchdog_enabled'. This helps simplify the code, for example: - In order to check if any of the two lockup detectors is enabled, it is sufficient to check if 'watchdog_enabled' is not zero. - In order to enable/disable one or both lockup detectors, it is sufficient to set/clear one or both bits in 'watchdog_enabled'. - Concurrent updates of 'watchdog_enabled' need not be synchronized via a spinlock or a mutex. Updates can either be atomic or concurrency can be detected by using 'cmpxchg'. Signed-off-by: Ulrich Obergfell Signed-off-by: Don Zickus --- include/linux/nmi.h | 2 ++ kernel/watchdog.c | 27 ++++++++++++++++++++++++++- 2 files changed, 28 insertions(+), 1 deletions(-) diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 9b2022a..3885a7d 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -68,6 +68,8 @@ static inline bool trigger_allbutself_cpu_backtrace(void) #ifdef CONFIG_LOCKUP_DETECTOR int hw_nmi_is_cpu_stuck(struct pt_regs *); u64 hw_nmi_get_sample_period(int watchdog_thresh); +extern int nmi_watchdog_enabled; +extern int soft_watchdog_enabled; extern int watchdog_user_enabled; extern int watchdog_thresh; extern int sysctl_softlockup_all_cpu_backtrace; diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 3174bf8..9a1c787 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -24,8 +24,33 @@ #include #include -int watchdog_user_enabled = 1; +/* + * The run state of the lockup detectors is controlled by the content of the + * 'watchdog_enabled' variable. Each lockup detector has its dedicated bit - + * bit 0 for the hard lockup detector and bit 1 for the soft lockup detector. + * + * 'watchdog_user_enabled', 'nmi_watchdog_enabled' and 'soft_watchdog_enabled' + * are variables that are only used as an 'interface' between the parameters + * in /proc/sys/kernel and the internal state bits in 'watchdog_enabled'. The + * 'watchdog_thresh' variable is handled differently because its value is not + * boolean, and the lockup detectors are 'suspended' while 'watchdog_thresh' + * is equal zero. + */ +#define NMI_WATCHDOG_ENABLED_BIT 0 +#define SOFT_WATCHDOG_ENABLED_BIT 1 +#define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT) +#define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT) + +#ifdef CONFIG_HARDLOCKUP_DETECTOR +static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED; +#else +static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED; +#endif +int __read_mostly nmi_watchdog_enabled; +int __read_mostly soft_watchdog_enabled; +int __read_mostly watchdog_user_enabled; int __read_mostly watchdog_thresh = 10; + #ifdef CONFIG_SMP int __read_mostly sysctl_softlockup_all_cpu_backtrace; #else -- 1.7.1