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Message-Id: <1413565588-4144-2-git-send-email-uobergfe@redhat.com> Date: Fri, 17 Oct 2014 19:06:20 +0200 From: Ulrich Obergfell <uobergfe@...hat.com> To: linux-kernel@...r.kernel.org Cc: dzickus@...hat.com, uobergfe@...hat.com Subject: [PATCH v2 1/9] watchdog: new definitions and variables, initialization 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 <uobergfe@...hat.com> --- include/linux/nmi.h | 2 ++ kernel/watchdog.c | 27 ++++++++++++++++++++++++++- 2 files changed, 28 insertions(+), 1 deletion(-) 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 49e9537..f8da756 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -24,8 +24,33 @@ #include <linux/kvm_para.h> #include <linux/perf_event.h> -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 -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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