On Thu 2015-10-15 11:06 -0400, Don Zickus wrote:
> The only way to enable a hardlockup to panic the machine is to set
> 'nmi_watchdog=panic' on the kernel command line.
>
> This makes it awkward for end users and folks who want to run automate tests
> (like myself).
>
> Mimic the softlockup_panic knob and create a /proc/sys/kernel/hardlockup_panic
> knob.
>
> Signed-off-by: Don Zickus <dzic...@redhat.com>
>
> --
> V2 - wrap the sysctl variable with CONFIG_HARDLOCKUP_DETECTOR (kbuid bot)
> ---
> Documentation/lockup-watchdogs.txt | 5 +++--
> include/linux/sched.h | 1 +
> kernel/sysctl.c | 11 +++++++++++
> kernel/watchdog.c | 2 +-
> 4 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/lockup-watchdogs.txt
> b/Documentation/lockup-watchdogs.txt
> index 22dd6af..4a6e33e 100644
> --- a/Documentation/lockup-watchdogs.txt
> +++ b/Documentation/lockup-watchdogs.txt
> @@ -20,8 +20,9 @@ kernel mode for more than 10 seconds (see "Implementation"
> below for
> details), without letting other interrupts have a chance to run.
> Similarly to the softlockup case, the current stack trace is displayed
> upon detection and the system will stay locked up unless the default
> -behavior is changed, which can be done through a compile time knob,
> -"BOOTPARAM_HARDLOCKUP_PANIC", and a kernel parameter, "nmi_watchdog"
> +behavior is changed, which can be done through a sysctl,
> +'hardlockup_panic', a compile time knob, "BOOTPARAM_HARDLOCKUP_PANIC",
> +and a kernel parameter, "nmi_watchdog"
> (see "Documentation/kernel-parameters.txt" for details).
>
> The panic option can be used in combination with panic_timeout (this
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index b7b9501..5e65b14 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -384,6 +384,7 @@ extern int proc_dowatchdog_thresh(struct ctl_table
> *table, int write,
> void __user *buffer,
> size_t *lenp, loff_t *ppos);
> extern unsigned int softlockup_panic;
> +extern unsigned int hardlockup_panic;
> void lockup_detector_init(void);
> #else
> static inline void touch_softlockup_watchdog(void)
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index efb0370..a341117 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -887,6 +887,17 @@ static struct ctl_table kern_table[] = {
> .extra1 = &zero,
> .extra2 = &one,
> },
> +#ifdef CONFIG_HARDLOCKUP_DETECTOR
> + {
> + .procname = "hardlockup_panic",
> + .data = &hardlockup_panic,
> + .maxlen = sizeof(int),
> + .mode = 0644,
> + .proc_handler = proc_dointvec_minmax,
> + .extra1 = &zero,
> + .extra2 = &one,
> + },
> +#endif
> #ifdef CONFIG_SMP
> {
> .procname = "softlockup_all_cpu_backtrace",
> diff --git a/kernel/watchdog.c b/kernel/watchdog.c
> index f6b32b8..0a23125 100644
> --- a/kernel/watchdog.c
> +++ b/kernel/watchdog.c
> @@ -112,7 +112,7 @@ static unsigned long soft_lockup_nmi_warn;
> * Should we panic when a soft-lockup or hard-lockup occurs:
> */
> #ifdef CONFIG_HARDLOCKUP_DETECTOR
> -static int hardlockup_panic =
> +unsigned int __read_mostly hardlockup_panic =
> CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
> static unsigned long hardlockup_allcpu_dumped;
> /*Reviewed-by: Aaron Tomlin <atom...@redhat.com>
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