Messages in this thread | | | Date | Wed, 13 Sep 2017 14:02:37 -0400 | From | Don Zickus <> | Subject | Re: [patch V2 25/29] lockup_detector: Implement init time detection of perf |
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On Tue, Sep 12, 2017 at 09:37:19PM +0200, Thomas Gleixner wrote: > Use the init time detection of the perf NMI watchdog to determine whether > the perf NMI watchdog is functional. If not disable it permanentely. It > won't come back magically at runtime. > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > Cc: Don Zickus <dzickus@redhat.com> > Cc: Chris Metcalf <cmetcalf@mellanox.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Sebastian Siewior <bigeasy@linutronix.de> > Cc: Nicholas Piggin <npiggin@gmail.com> > Cc: Ulrich Obergfell <uobergfe@redhat.com> > Cc: Borislav Petkov <bp@alien8.de> > Cc: Andrew Morton <akpm@linux-foundation.org> > Link: http://lkml.kernel.org/r/20170831073054.997264122@linutronix.de > > --- > kernel/watchdog.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > --- a/kernel/watchdog.c > +++ b/kernel/watchdog.c > @@ -44,6 +44,7 @@ int __read_mostly watchdog_user_enabled > int __read_mostly nmi_watchdog_user_enabled = NMI_WATCHDOG_DEFAULT; > int __read_mostly soft_watchdog_user_enabled = 1; > int __read_mostly watchdog_thresh = 10; > +int __read_mostly nmi_watchdog_available; > > struct cpumask watchdog_allowed_mask __read_mostly; > static bool softlockup_threads_initialized __read_mostly; > @@ -114,6 +115,12 @@ void __weak watchdog_nmi_disable(unsigne > hardlockup_detector_perf_disable(); > } > > +/* Return 0, if a NMI watchdog is available. Error code otherwise */ > +int __weak __init void watchdog_nmi_probe(void)
^^^ compile error, can't have 'int' and 'void'. Removing 'void' fixes it.
Cheers, Don
> +{ > + return hardlockup_detector_perf_init(); > +} > + > /** > * watchdog_nmi_reconfigure - Optional function to reconfigure NMI watchdogs > * @run: If false stop the watchdogs on all enabled CPUs > @@ -145,7 +152,7 @@ static void lockup_detector_update_enabl > watchdog_enabled = 0; > if (!watchdog_user_enabled) > return; > - if (nmi_watchdog_user_enabled) > + if (nmi_watchdog_available && nmi_watchdog_user_enabled) > watchdog_enabled |= NMI_WATCHDOG_ENABLED; > if (soft_watchdog_user_enabled) > watchdog_enabled |= SOFT_WATCHDOG_ENABLED; > @@ -692,6 +699,8 @@ int proc_watchdog(struct ctl_table *tabl > int proc_nmi_watchdog(struct ctl_table *table, int write, > void __user *buffer, size_t *lenp, loff_t *ppos) > { > + if (!nmi_watchdog_available && write) > + return -ENOTSUPP; > return proc_watchdog_common(NMI_WATCHDOG_ENABLED, > table, write, buffer, lenp, ppos); > } > @@ -764,5 +773,7 @@ void __init lockup_detector_init(void) > cpumask_copy(&watchdog_cpumask, cpu_possible_mask); > #endif > > + if (!watchdog_nmi_probe()) > + nmi_watchdog_available = true; > softlockup_init_threads(); > } > >
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