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Commit 6592ad2f authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
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watchdog/core, powerpc: Make watchdog_nmi_reconfigure() two stage 



Both the perf reconfiguration and the powerpc watchdog_nmi_reconfigure()
need to be done in two steps.

     1) Stop all NMIs
     2) Read the new parameters and start NMIs

Right now watchdog_nmi_reconfigure() is a combination of both. To allow a
clean reconfiguration add a 'run' argument and split the functionality in
powerpc.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarDon Zickus <dzickus@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20170912194147.862865570@linutronix.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 7feeb9cd

arch/powerpc/kernel/watchdog.c

+9 −8
Original line number Diff line number Diff line
@@ -355,18 +355,19 @@ static void watchdog_calc_timeouts(void) 
	wd_timer_period_ms = watchdog_thresh * 1000 * 2 / 5;

}



void watchdog_nmi_reconfigure(void)

void watchdog_nmi_reconfigure(bool run)

{

	int cpu;



	watchdog_calc_timeouts();



	if (!run) {

		for_each_cpu(cpu, &wd_cpus_enabled)

			stop_wd_on_cpu(cpu);



	} else {

		watchdog_calc_timeouts();

		for_each_cpu_and(cpu, cpu_online_mask, &watchdog_cpumask)

			start_wd_on_cpu(cpu);

	}

}



/*

 * This runs after lockup_detector_init() which sets up watchdog_cpumask.

include/linux/nmi.h

+2 −0
Original line number Diff line number Diff line
@@ -103,6 +103,8 @@ static inline void arch_touch_nmi_watchdog(void) {} 
#endif

#endif



void watchdog_nmi_reconfigure(bool run);



/**

 * touch_nmi_watchdog - restart NMI watchdog timeout.

 *

kernel/watchdog.c

+22 −9
Original line number Diff line number Diff line
@@ -112,17 +112,25 @@ void __weak watchdog_nmi_disable(unsigned int cpu) 
	hardlockup_detector_perf_disable();

}



/*

 * watchdog_nmi_reconfigure can be implemented to be notified after any

 * watchdog configuration change. The arch hardlockup watchdog should

 * respond to the following variables:

/**

 * watchdog_nmi_reconfigure - Optional function to reconfigure NMI watchdogs

 * @run:	If false stop the watchdogs on all enabled CPUs

 *		If true start the watchdogs on all enabled CPUs

 *

 * The core call order is:

 * watchdog_nmi_reconfigure(false);

 * update_variables();

 * watchdog_nmi_reconfigure(true);

 *

 * The second call which starts the watchdogs again guarantees that the

 * following variables are stable across the call.

 * - watchdog_enabled

 * - watchdog_thresh

 * - watchdog_cpumask

 * - sysctl_hardlockup_all_cpu_backtrace

 * - hardlockup_panic

 *

 * After the call the variables can be changed again.

 */

void __weak watchdog_nmi_reconfigure(void) { }

void __weak watchdog_nmi_reconfigure(bool run) { }



#ifdef CONFIG_SOFTLOCKUP_DETECTOR
@@ -515,10 +523,12 @@ static void softlockup_unpark_threads(void) 


static void softlockup_reconfigure_threads(bool enabled)

{

	watchdog_nmi_reconfigure(false);

	softlockup_park_all_threads();

	set_sample_period();

	if (enabled)

		softlockup_unpark_threads();

	watchdog_nmi_reconfigure(true);

}



/*
@@ -559,7 +569,11 @@ static inline void watchdog_unpark_threads(void) { } 
static inline int watchdog_enable_all_cpus(void) { return 0; }

static inline void watchdog_disable_all_cpus(void) { }

static inline void softlockup_init_threads(void) { }

static inline void softlockup_reconfigure_threads(bool enabled) { }

static void softlockup_reconfigure_threads(bool enabled)

{

	watchdog_nmi_reconfigure(false);

	watchdog_nmi_reconfigure(true);

}

#endif /* !CONFIG_SOFTLOCKUP_DETECTOR */



static void __lockup_detector_cleanup(void)
@@ -599,7 +613,6 @@ static void proc_watchdog_update(void) 
	/* Remove impossible cpus to keep sysctl output clean. */

	cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask);

	softlockup_reconfigure_threads(watchdog_enabled && watchdog_thresh);

	watchdog_nmi_reconfigure();

}



/*