Commit a10a842f authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Linus Torvalds
Browse files

kernel/watchdog: provide watchdog_nmi_reconfigure() for arch watchdogs 

After reconfiguring watchdog sysctls etc., architecture specific
watchdogs may not get all their parameters updated.

watchdog_nmi_reconfigure() can be implemented to pull the new values in
and set the arch NMI watchdog.

[npiggin@gmail.com: add code comments]
  Link: http://lkml.kernel.org/r/20170617125933.774d3858@roar.ozlabs.ibm.com
[arnd@arndb.de: hide unused function]
  Link: http://lkml.kernel.org/r/20170620204854.966601-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/20170616065715.18390-5-npiggin@gmail.com


Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarDon Zickus <dzickus@redhat.com>
Tested-by: Babu Moger <babu.moger@oracle.com>	[sparc]
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 05a4a952

kernel/watchdog.c

+44 −4
Original line number Diff line number Diff line
@@ -114,6 +114,10 @@ int __read_mostly watchdog_suspended; 
/*

 * These functions can be overridden if an architecture implements its

 * own hardlockup detector.

 *

 * watchdog_nmi_enable/disable can be implemented to start and stop when

 * softlockup watchdog threads start and stop. The arch must select the

 * SOFTLOCKUP_DETECTOR Kconfig.

 */

int __weak watchdog_nmi_enable(unsigned int cpu)

{
@@ -123,6 +127,22 @@ void __weak watchdog_nmi_disable(unsigned int cpu) 
{

}



/*

 * watchdog_nmi_reconfigure can be implemented to be notified after any

 * watchdog configuration change. The arch hardlockup watchdog should

 * respond to the following variables:

 * - nmi_watchdog_enabled

 * - watchdog_thresh

 * - watchdog_cpumask

 * - sysctl_hardlockup_all_cpu_backtrace

 * - hardlockup_panic

 * - watchdog_suspended

 */

void __weak watchdog_nmi_reconfigure(void)

{

}





#ifdef CONFIG_SOFTLOCKUP_DETECTOR



/* Helper for online, unparked cpus. */
@@ -600,6 +620,14 @@ static void watchdog_disable_all_cpus(void) 
	}

}



#ifdef CONFIG_SYSCTL

static int watchdog_update_cpus(void)

{

	return smpboot_update_cpumask_percpu_thread(

		    &watchdog_threads, &watchdog_cpumask);

}

#endif



#else /* SOFTLOCKUP */

static int watchdog_park_threads(void)

{
@@ -619,6 +647,13 @@ static void watchdog_disable_all_cpus(void) 
{

}



#ifdef CONFIG_SYSCTL

static int watchdog_update_cpus(void)

{

	return 0;

}

#endif



static void set_sample_period(void)

{

}
@@ -651,6 +686,8 @@ int lockup_detector_suspend(void) 
		watchdog_enabled = 0;

	}



	watchdog_nmi_reconfigure();



	mutex_unlock(&watchdog_proc_mutex);



	return ret;
@@ -671,6 +708,8 @@ void lockup_detector_resume(void) 
	if (watchdog_running && !watchdog_suspended)

		watchdog_unpark_threads();



	watchdog_nmi_reconfigure();



	mutex_unlock(&watchdog_proc_mutex);

	put_online_cpus();

}
@@ -696,6 +735,8 @@ static int proc_watchdog_update(void) 
	else

		watchdog_disable_all_cpus();



	watchdog_nmi_reconfigure();



	return err;



}
@@ -881,12 +922,11 @@ 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)

			if (watchdog_update_cpus() != 0)

				pr_err("cpumask update failed\n");

#endif

		}



		watchdog_nmi_reconfigure();

	}

out:

	mutex_unlock(&watchdog_proc_mutex);

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