Message-ID: <20170614140937.qrkajknqxldwdkv2@redhat.com>
Date:   Wed, 14 Jun 2017 10:09:37 -0400
From:   Don Zickus <dzickus@...hat.com>
To:     Nicholas Piggin <npiggin@...il.com>, babu.moger@...cle.com
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH 3/4] watchdog: Split up config options

On Wed, Jun 14, 2017 at 02:11:18AM +1000, Nicholas Piggin wrote:
> > Yeah, if you wouldn't mind.  Sorry for dragging this out, but I feel like we
> > are getting close to have this defined properly which would allow us to
> > split the code up correctly in the future.
> 
> How's this for a replacement patch 3? I think the Kconfig works out much
> better now.

Hi Nick,

I think you made this much clearer, thank you!  I am good with this.


Hi Babu,

Can you give this patchset (and particularly this version of patch 3) a try
on sparc to make sure we didn't break anything?  I believe this should
resolve the start nmi watchdog on boot issue you noticed.  Thanks!

Cheers,
Don

> --
> 
> Split SOFTLOCKUP_DETECTOR from LOCKUP_DETECTOR, and split
> HARDLOCKUP_DETECTOR_PERF from HARDLOCKUP_DETECTOR.
> 
> LOCKUP_DETECTOR implies the general boot, sysctl, and programming
> interfaces for the lockup detectors.
> 
> An architecture that wants to use a hard lockup detector must define
> HAVE_HARDLOCKUP_DETECTOR_PERF or HAVE_HARDLOCKUP_DETECTOR_ARCH.
> 
> Alternatively an arch can define HAVE_NMI_WATCHDOG, which provides
> the minimum arch_touch_nmi_watchdog, and it otherwise does its own
> thing and does not implement the LOCKUP_DETECTOR interfaces.
> 
> sparc is unusual in that it has started to implement some of the
> interfaces, but not fully yet. It should probably be converted to
> a full HAVE_HARDLOCKUP_DETECTOR_ARCH.
> 
> Signed-off-by: Nicholas Piggin <npiggin@...il.com>
> ---
>  arch/Kconfig                   |  23 ++++
>  arch/powerpc/Kconfig           |   1 +
>  arch/powerpc/kernel/setup_64.c |   2 +-
>  arch/x86/Kconfig               |   1 +
>  arch/x86/kernel/apic/hw_nmi.c  |   2 +-
>  include/linux/nmi.h            |  29 +++--
>  kernel/Makefile                |   2 +-
>  kernel/sysctl.c                |  16 +--
>  kernel/watchdog.c              | 238 ++++++++++++++++++++++++++---------------
>  kernel/watchdog_hld.c          |  32 ------
>  lib/Kconfig.debug              |  26 +++--
>  11 files changed, 231 insertions(+), 141 deletions(-)
> 
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 6c00e5b00f8b..878addc6f141 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -288,6 +288,29 @@ config HAVE_PERF_EVENTS_NMI
>  	  subsystem.  Also has support for calculating CPU cycle events
>  	  to determine how many clock cycles in a given period.
>  
> +
> +config HAVE_HARDLOCKUP_DETECTOR_PERF
> +	bool
> +	depends on HAVE_PERF_EVENTS_NMI
> +	help
> +	  The arch chooses to use the generic perf-NMI-based hardlockup
> +	  detector. Must define HAVE_PERF_EVENTS_NMI.
> +
> +config HAVE_NMI_WATCHDOG
> +	bool
> +	help
> +	  The arch provides a low level NMI watchdog. It provides
> +	  asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
> +
> +config HAVE_HARDLOCKUP_DETECTOR_ARCH
> +	bool
> +	select HAVE_NMI_WATCHDOG
> +	help
> +	  The arch chooses to provide its own hardlockup detector, which is
> +	  a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
> +	  interfaces and parameters provided by hardlockup detector subsystem.
> +
> +
>  config HAVE_PERF_REGS
>  	bool
>  	help
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index f7c8f9972f61..7aba96ec3378 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -202,6 +202,7 @@ config PPC
>  	select HAVE_OPTPROBES			if PPC64
>  	select HAVE_PERF_EVENTS
>  	select HAVE_PERF_EVENTS_NMI		if PPC64
> +	select HAVE_HARDLOCKUP_DETECTOR_PERF	if HAVE_PERF_EVENTS_NMI
>  	select HAVE_PERF_REGS
>  	select HAVE_PERF_USER_STACK_DUMP
>  	select HAVE_RCU_TABLE_FREE		if SMP
> diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
> index f35ff9dea4fb..ab650905f75a 100644
> --- a/arch/powerpc/kernel/setup_64.c
> +++ b/arch/powerpc/kernel/setup_64.c
> @@ -727,7 +727,7 @@ struct ppc_pci_io ppc_pci_io;
>  EXPORT_SYMBOL(ppc_pci_io);
>  #endif
>  
> -#ifdef CONFIG_HARDLOCKUP_DETECTOR
> +#ifdef CONFIG_HARDLOCKUP_DETECTOR_PERF
>  u64 hw_nmi_get_sample_period(int watchdog_thresh)
>  {
>  	return ppc_proc_freq * watchdog_thresh;
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 4ccfacc7232a..3c084149b5d1 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -157,6 +157,7 @@ config X86
>  	select HAVE_PCSPKR_PLATFORM
>  	select HAVE_PERF_EVENTS
>  	select HAVE_PERF_EVENTS_NMI
> +	select HAVE_HARDLOCKUP_DETECTOR_PERF	if HAVE_PERF_EVENTS_NMI
>  	select HAVE_PERF_REGS
>  	select HAVE_PERF_USER_STACK_DUMP
>  	select HAVE_REGS_AND_STACK_ACCESS_API
> diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
> index c73c9fb281e1..d6f387780849 100644
> --- a/arch/x86/kernel/apic/hw_nmi.c
> +++ b/arch/x86/kernel/apic/hw_nmi.c
> @@ -19,7 +19,7 @@
>  #include <linux/init.h>
>  #include <linux/delay.h>
>  
> -#ifdef CONFIG_HARDLOCKUP_DETECTOR
> +#ifdef CONFIG_HARDLOCKUP_DETECTOR_PERF
>  u64 hw_nmi_get_sample_period(int watchdog_thresh)
>  {
>  	return (u64)(cpu_khz) * 1000 * watchdog_thresh;
> diff --git a/include/linux/nmi.h b/include/linux/nmi.h
> index bd387ef8bccd..8aa01fd859fb 100644
> --- a/include/linux/nmi.h
> +++ b/include/linux/nmi.h
> @@ -11,13 +11,21 @@
>  #endif
>  
>  #ifdef CONFIG_LOCKUP_DETECTOR
> +void lockup_detector_init(void);
> +#else
> +static inline void lockup_detector_init(void)
> +{
> +}
> +#endif
> +
> +#ifdef CONFIG_SOFTLOCKUP_DETECTOR
>  extern void touch_softlockup_watchdog_sched(void);
>  extern void touch_softlockup_watchdog(void);
>  extern void touch_softlockup_watchdog_sync(void);
>  extern void touch_all_softlockup_watchdogs(void);
>  extern unsigned int  softlockup_panic;
> -extern unsigned int  hardlockup_panic;
> -void lockup_detector_init(void);
> +extern int soft_watchdog_enabled;
> +extern atomic_t watchdog_park_in_progress;
>  #else
>  static inline void touch_softlockup_watchdog_sched(void)
>  {
> @@ -31,9 +39,6 @@ static inline void touch_softlockup_watchdog_sync(void)
>  static inline void touch_all_softlockup_watchdogs(void)
>  {
>  }
> -static inline void lockup_detector_init(void)
> -{
> -}
>  #endif
>  
>  #ifdef CONFIG_DETECT_HUNG_TASK
> @@ -63,15 +68,18 @@ static inline void reset_hung_task_detector(void)
>  
>  #if defined(CONFIG_HARDLOCKUP_DETECTOR)
>  extern void hardlockup_detector_disable(void);
> +extern unsigned int hardlockup_panic;
>  #else
>  static inline void hardlockup_detector_disable(void) {}
>  #endif
>  
> -#if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG)
> +#if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF)
>  extern void arch_touch_nmi_watchdog(void);
>  #else
> +#if !defined(CONFIG_HAVE_NMI_WATCHDOG)
>  static inline void arch_touch_nmi_watchdog(void) {}
>  #endif
> +#endif
>  
>  /**
>   * touch_nmi_watchdog - restart NMI watchdog timeout.
> @@ -141,15 +149,18 @@ static inline bool trigger_single_cpu_backtrace(int cpu)
>  }
>  #endif
>  
> -#ifdef CONFIG_LOCKUP_DETECTOR
> +#ifdef CONFIG_HARDLOCKUP_DETECTOR_PERF
>  u64 hw_nmi_get_sample_period(int watchdog_thresh);
> +#endif
> +
> +#ifdef CONFIG_LOCKUP_DETECTOR
>  extern int nmi_watchdog_enabled;
> -extern int soft_watchdog_enabled;
>  extern int watchdog_user_enabled;
>  extern int watchdog_thresh;
>  extern unsigned long watchdog_enabled;
> +extern struct cpumask watchdog_cpumask;
>  extern unsigned long *watchdog_cpumask_bits;
> -extern atomic_t watchdog_park_in_progress;
> +extern int __read_mostly watchdog_suspended;
>  #ifdef CONFIG_SMP
>  extern int sysctl_softlockup_all_cpu_backtrace;
>  extern int sysctl_hardlockup_all_cpu_backtrace;
> diff --git a/kernel/Makefile b/kernel/Makefile
> index 72aa080f91f0..4cb8e8b23c6e 100644
> --- a/kernel/Makefile
> +++ b/kernel/Makefile
> @@ -82,7 +82,7 @@ obj-$(CONFIG_KPROBES) += kprobes.o
>  obj-$(CONFIG_KGDB) += debug/
>  obj-$(CONFIG_DETECT_HUNG_TASK) += hung_task.o
>  obj-$(CONFIG_LOCKUP_DETECTOR) += watchdog.o
> -obj-$(CONFIG_HARDLOCKUP_DETECTOR) += watchdog_hld.o
> +obj-$(CONFIG_HARDLOCKUP_DETECTOR_PERF) += watchdog_hld.o
>  obj-$(CONFIG_SECCOMP) += seccomp.o
>  obj-$(CONFIG_RELAY) += relay.o
>  obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 4dfba1a76cc3..46b189fd865b 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -880,6 +880,14 @@ static struct ctl_table kern_table[] = {
>  #endif
>  	},
>  	{
> +		.procname	= "watchdog_cpumask",
> +		.data		= &watchdog_cpumask_bits,
> +		.maxlen		= NR_CPUS,
> +		.mode		= 0644,
> +		.proc_handler	= proc_watchdog_cpumask,
> +	},
> +#ifdef CONFIG_SOFTLOCKUP_DETECTOR
> +	{
>  		.procname       = "soft_watchdog",
>  		.data           = &soft_watchdog_enabled,
>  		.maxlen         = sizeof (int),
> @@ -889,13 +897,6 @@ static struct ctl_table kern_table[] = {
>  		.extra2		= &one,
>  	},
>  	{
> -		.procname	= "watchdog_cpumask",
> -		.data		= &watchdog_cpumask_bits,
> -		.maxlen		= NR_CPUS,
> -		.mode		= 0644,
> -		.proc_handler	= proc_watchdog_cpumask,
> -	},
> -	{
>  		.procname	= "softlockup_panic",
>  		.data		= &softlockup_panic,
>  		.maxlen		= sizeof(int),
> @@ -904,6 +905,7 @@ static struct ctl_table kern_table[] = {
>  		.extra1		= &zero,
>  		.extra2		= &one,
>  	},
> +#endif
>  #ifdef CONFIG_HARDLOCKUP_DETECTOR
>  	{
>  		.procname	= "hardlockup_panic",
> diff --git a/kernel/watchdog.c b/kernel/watchdog.c
> index 03e0b69bb5bf..deb010505646 100644
> --- a/kernel/watchdog.c
> +++ b/kernel/watchdog.c
> @@ -29,15 +29,55 @@
>  #include <linux/kvm_para.h>
>  #include <linux/kthread.h>
>  
> +/* Watchdog configuration */
>  static DEFINE_MUTEX(watchdog_proc_mutex);
>  
> -#if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTOR)
> +int __read_mostly nmi_watchdog_enabled;
> +
> +#ifdef CONFIG_HARDLOCKUP_DETECTOR
>  unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED;
> +
> +/* boot commands */
> +/*
> + * Should we panic when a soft-lockup or hard-lockup occurs:
> + */
> +unsigned int __read_mostly hardlockup_panic =
> +			CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
> +/*
> + * We may not want to enable hard lockup detection by default in all cases,
> + * for example when running the kernel as a guest on a hypervisor. In these
> + * cases this function can be called to disable hard lockup detection. This
> + * function should only be executed once by the boot processor before the
> + * kernel command line parameters are parsed, because otherwise it is not
> + * possible to override this in hardlockup_panic_setup().
> + */
> +void hardlockup_detector_disable(void)
> +{
> +	watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
> +}
> +
> +static int __init hardlockup_panic_setup(char *str)
> +{
> +	if (!strncmp(str, "panic", 5))
> +		hardlockup_panic = 1;
> +	else if (!strncmp(str, "nopanic", 7))
> +		hardlockup_panic = 0;
> +	else if (!strncmp(str, "0", 1))
> +		watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
> +	else if (!strncmp(str, "1", 1))
> +		watchdog_enabled |= NMI_WATCHDOG_ENABLED;
> +	return 1;
> +}
> +__setup("nmi_watchdog=", hardlockup_panic_setup);
> +
>  #else
>  unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED;
>  #endif
> -int __read_mostly nmi_watchdog_enabled;
> +
> +#ifdef CONFIG_SOFTLOCKUP_DETECTOR
>  int __read_mostly soft_watchdog_enabled;
> +#endif
> +
>  int __read_mostly watchdog_user_enabled;
>  int __read_mostly watchdog_thresh = 10;
>  
> @@ -45,15 +85,9 @@ int __read_mostly watchdog_thresh = 10;
>  int __read_mostly sysctl_softlockup_all_cpu_backtrace;
>  int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
>  #endif
> -static struct cpumask watchdog_cpumask __read_mostly;
> +struct cpumask watchdog_cpumask __read_mostly;
>  unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
>  
> -/* Helper for online, unparked cpus. */
> -#define for_each_watchdog_cpu(cpu) \
> -	for_each_cpu_and((cpu), cpu_online_mask, &watchdog_cpumask)
> -
> -atomic_t watchdog_park_in_progress = ATOMIC_INIT(0);
> -
>  /*
>   * The 'watchdog_running' variable is set to 1 when the watchdog threads
>   * are registered/started and is set to 0 when the watchdog threads are
> @@ -72,7 +106,27 @@ static int __read_mostly watchdog_running;
>   * of 'watchdog_running' cannot change while the watchdog is deactivated
>   * temporarily (see related code in 'proc' handlers).
>   */
> -static int __read_mostly watchdog_suspended;
> +int __read_mostly watchdog_suspended;
> +
> +/*
> + * These functions can be overridden if an architecture implements its
> + * own hardlockup detector.
> + */
> +int __weak watchdog_nmi_enable(unsigned int cpu)
> +{
> +	return 0;
> +}
> +void __weak watchdog_nmi_disable(unsigned int cpu)
> +{
> +}
> +
> +#ifdef CONFIG_SOFTLOCKUP_DETECTOR
> +
> +/* Helper for online, unparked cpus. */
> +#define for_each_watchdog_cpu(cpu) \
> +	for_each_cpu_and((cpu), cpu_online_mask, &watchdog_cpumask)
> +
> +atomic_t watchdog_park_in_progress = ATOMIC_INIT(0);
>  
>  static u64 __read_mostly sample_period;
>  
> @@ -120,6 +174,7 @@ static int __init softlockup_all_cpu_backtrace_setup(char *str)
>  	return 1;
>  }
>  __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup);
> +#ifdef CONFIG_HARDLOCKUP_DETECTOR
>  static int __init hardlockup_all_cpu_backtrace_setup(char *str)
>  {
>  	sysctl_hardlockup_all_cpu_backtrace =
> @@ -128,6 +183,7 @@ static int __init hardlockup_all_cpu_backtrace_setup(char *str)
>  }
>  __setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup);
>  #endif
> +#endif
>  
>  /*
>   * Hard-lockup warnings should be triggered after just a few seconds. Soft-
> @@ -213,18 +269,6 @@ void touch_softlockup_watchdog_sync(void)
>  	__this_cpu_write(watchdog_touch_ts, 0);
>  }
>  
> -/* watchdog detector functions */
> -bool is_hardlockup(void)
> -{
> -	unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
> -
> -	if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
> -		return true;
> -
> -	__this_cpu_write(hrtimer_interrupts_saved, hrint);
> -	return false;
> -}
> -
>  static int is_softlockup(unsigned long touch_ts)
>  {
>  	unsigned long now = get_timestamp();
> @@ -237,21 +281,21 @@ static int is_softlockup(unsigned long touch_ts)
>  	return 0;
>  }
>  
> -static void watchdog_interrupt_count(void)
> +/* watchdog detector functions */
> +bool is_hardlockup(void)
>  {
> -	__this_cpu_inc(hrtimer_interrupts);
> -}
> +	unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
>  
> -/*
> - * These two functions are mostly architecture specific
> - * defining them as weak here.
> - */
> -int __weak watchdog_nmi_enable(unsigned int cpu)
> -{
> -	return 0;
> +	if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
> +		return true;
> +
> +	__this_cpu_write(hrtimer_interrupts_saved, hrint);
> +	return false;
>  }
> -void __weak watchdog_nmi_disable(unsigned int cpu)
> +
> +static void watchdog_interrupt_count(void)
>  {
> +	__this_cpu_inc(hrtimer_interrupts);
>  }
>  
>  static int watchdog_enable_all_cpus(void);
> @@ -502,57 +546,6 @@ static void watchdog_unpark_threads(void)
>  		kthread_unpark(per_cpu(softlockup_watchdog, cpu));
>  }
>  
> -/*
> - * Suspend the hard and soft lockup detector by parking the watchdog threads.
> - */
> -int lockup_detector_suspend(void)
> -{
> -	int ret = 0;
> -
> -	get_online_cpus();
> -	mutex_lock(&watchdog_proc_mutex);
> -	/*
> -	 * Multiple suspend requests can be active in parallel (counted by
> -	 * the 'watchdog_suspended' variable). If the watchdog threads are
> -	 * running, the first caller takes care that they will be parked.
> -	 * The state of 'watchdog_running' cannot change while a suspend
> -	 * request is active (see related code in 'proc' handlers).
> -	 */
> -	if (watchdog_running && !watchdog_suspended)
> -		ret = watchdog_park_threads();
> -
> -	if (ret == 0)
> -		watchdog_suspended++;
> -	else {
> -		watchdog_disable_all_cpus();
> -		pr_err("Failed to suspend lockup detectors, disabled\n");
> -		watchdog_enabled = 0;
> -	}
> -
> -	mutex_unlock(&watchdog_proc_mutex);
> -
> -	return ret;
> -}
> -
> -/*
> - * Resume the hard and soft lockup detector by unparking the watchdog threads.
> - */
> -void lockup_detector_resume(void)
> -{
> -	mutex_lock(&watchdog_proc_mutex);
> -
> -	watchdog_suspended--;
> -	/*
> -	 * The watchdog threads are unparked if they were previously running
> -	 * and if there is no more active suspend request.
> -	 */
> -	if (watchdog_running && !watchdog_suspended)
> -		watchdog_unpark_threads();
> -
> -	mutex_unlock(&watchdog_proc_mutex);
> -	put_online_cpus();
> -}
> -
>  static int update_watchdog_all_cpus(void)
>  {
>  	int ret;
> @@ -604,6 +597,81 @@ static void watchdog_disable_all_cpus(void)
>  	}
>  }
>  
> +#else /* SOFTLOCKUP */
> +static int watchdog_park_threads(void)
> +{
> +	return 0;
> +}
> +
> +static void watchdog_unpark_threads(void)
> +{
> +}
> +
> +static int watchdog_enable_all_cpus(void)
> +{
> +	return 0;
> +}
> +
> +static void watchdog_disable_all_cpus(void)
> +{
> +}
> +
> +static void set_sample_period(void)
> +{
> +}
> +#endif /* SOFTLOCKUP */
> +
> +/*
> + * Suspend the hard and soft lockup detector by parking the watchdog threads.
> + */
> +int lockup_detector_suspend(void)
> +{
> +	int ret = 0;
> +
> +	get_online_cpus();
> +	mutex_lock(&watchdog_proc_mutex);
> +	/*
> +	 * Multiple suspend requests can be active in parallel (counted by
> +	 * the 'watchdog_suspended' variable). If the watchdog threads are
> +	 * running, the first caller takes care that they will be parked.
> +	 * The state of 'watchdog_running' cannot change while a suspend
> +	 * request is active (see related code in 'proc' handlers).
> +	 */
> +	if (watchdog_running && !watchdog_suspended)
> +		ret = watchdog_park_threads();
> +
> +	if (ret == 0)
> +		watchdog_suspended++;
> +	else {
> +		watchdog_disable_all_cpus();
> +		pr_err("Failed to suspend lockup detectors, disabled\n");
> +		watchdog_enabled = 0;
> +	}
> +
> +	mutex_unlock(&watchdog_proc_mutex);
> +
> +	return ret;
> +}
> +
> +/*
> + * Resume the hard and soft lockup detector by unparking the watchdog threads.
> + */
> +void lockup_detector_resume(void)
> +{
> +	mutex_lock(&watchdog_proc_mutex);
> +
> +	watchdog_suspended--;
> +	/*
> +	 * The watchdog threads are unparked if they were previously running
> +	 * and if there is no more active suspend request.
> +	 */
> +	if (watchdog_running && !watchdog_suspended)
> +		watchdog_unpark_threads();
> +
> +	mutex_unlock(&watchdog_proc_mutex);
> +	put_online_cpus();
> +}
> +
>  #ifdef CONFIG_SYSCTL
>  
>  /*
> @@ -810,9 +878,11 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write,
>  			 * a temporary cpumask, so we are likely not in a
>  			 * position to do much else to make things better.
>  			 */
> +#ifdef CONFIG_SOFTLOCKUP_DETECTOR
>  			if (smpboot_update_cpumask_percpu_thread(
>  				    &watchdog_threads, &watchdog_cpumask) != 0)
>  				pr_err("cpumask update failed\n");
> +#endif
>  		}
>  	}
>  out:
> diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
> index 90d688df6ce1..295a0d84934c 100644
> --- a/kernel/watchdog_hld.c
> +++ b/kernel/watchdog_hld.c
> @@ -22,39 +22,7 @@ static DEFINE_PER_CPU(bool, hard_watchdog_warn);
>  static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
>  static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
>  
> -/* boot commands */
> -/*
> - * Should we panic when a soft-lockup or hard-lockup occurs:
> - */
> -unsigned int __read_mostly hardlockup_panic =
> -			CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
>  static unsigned long hardlockup_allcpu_dumped;
> -/*
> - * We may not want to enable hard lockup detection by default in all cases,
> - * for example when running the kernel as a guest on a hypervisor. In these
> - * cases this function can be called to disable hard lockup detection. This
> - * function should only be executed once by the boot processor before the
> - * kernel command line parameters are parsed, because otherwise it is not
> - * possible to override this in hardlockup_panic_setup().
> - */
> -void hardlockup_detector_disable(void)
> -{
> -	watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
> -}
> -
> -static int __init hardlockup_panic_setup(char *str)
> -{
> -	if (!strncmp(str, "panic", 5))
> -		hardlockup_panic = 1;
> -	else if (!strncmp(str, "nopanic", 7))
> -		hardlockup_panic = 0;
> -	else if (!strncmp(str, "0", 1))
> -		watchdog_enabled &= ~NMI_WATCHDOG_ENABLED;
> -	else if (!strncmp(str, "1", 1))
> -		watchdog_enabled |= NMI_WATCHDOG_ENABLED;
> -	return 1;
> -}
> -__setup("nmi_watchdog=", hardlockup_panic_setup);
>  
>  void arch_touch_nmi_watchdog(void)
>  {
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index e4587ebe52c7..f87a559dd178 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -801,10 +801,24 @@ config LOCKUP_DETECTOR
>  	  The frequency of hrtimer and NMI events and the soft and hard lockup
>  	  thresholds can be controlled through the sysctl watchdog_thresh.
>  
> +config SOFTLOCKUP_DETECTOR
> +	bool "Detect Soft Lockups"
> +	depends on LOCKUP_DETECTOR
> +
> +config HARDLOCKUP_DETECTOR_PERF
> +	bool
> +	select SOFTLOCKUP_DETECTOR
> +
> +#
> +# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
> +# lockup detector rather than the perf based detector.
> +#
>  config HARDLOCKUP_DETECTOR
> -	def_bool y
> -	depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
> -	depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
> +	bool "Detect Hard Lockups"
> +	depends on LOCKUP_DETECTOR
> +	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
> +	select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
> +	select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
>  
>  config BOOTPARAM_HARDLOCKUP_PANIC
>  	bool "Panic (Reboot) On Hard Lockups"
> @@ -826,7 +840,7 @@ config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
>  
>  config BOOTPARAM_SOFTLOCKUP_PANIC
>  	bool "Panic (Reboot) On Soft Lockups"
> -	depends on LOCKUP_DETECTOR
> +	depends on SOFTLOCKUP_DETECTOR
>  	help
>  	  Say Y here to enable the kernel to panic on "soft lockups",
>  	  which are bugs that cause the kernel to loop in kernel
> @@ -843,7 +857,7 @@ config BOOTPARAM_SOFTLOCKUP_PANIC
>  
>  config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
>  	int
> -	depends on LOCKUP_DETECTOR
> +	depends on SOFTLOCKUP_DETECTOR
>  	range 0 1
>  	default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
>  	default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
> @@ -851,7 +865,7 @@ config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
>  config DETECT_HUNG_TASK
>  	bool "Detect Hung Tasks"
>  	depends on DEBUG_KERNEL
> -	default LOCKUP_DETECTOR
> +	default SOFTLOCKUP_DETECTOR
>  	help
>  	  Say Y here to enable the kernel to detect "hung tasks",
>  	  which are bugs that cause the task to be stuck in
> -- 
> 2.11.0
> 

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