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Commit 7a5c8b57 authored by Babu Moger's avatar Babu Moger Committed by Linus Torvalds
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sparc: implement watchdog_nmi_enable and watchdog_nmi_disable 

Implement functions watchdog_nmi_enable and watchdog_nmi_disable to
enable/disable nmi watchdog.  Sparc uses arch specific nmi watchdog
handler.  Currently, we do not have a way to enable/disable nmi watchdog
dynamically.  With these patches we can enable or disable arch specific
nmi watchdogs using proc or sysctl interface.

Example commands.
To enable: echo 1 >  /proc/sys/kernel/nmi_watchdog
To disable: echo 0 >  /proc/sys/kernel/nmi_watchdog

It can also achieved using the sysctl parameter kernel.nmi_watchdog

Link: http://lkml.kernel.org/r/1478034826-43888-4-git-send-email-babu.moger@oracle.com


Signed-off-by: default avatarBabu Moger <babu.moger@oracle.com>
Acked-by: default avatarDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Josh Hunt <johunt@akamai.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 73ce0511

arch/sparc/kernel/nmi.c

+43 −1
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ static int panic_on_timeout; 
 */

atomic_t nmi_active = ATOMIC_INIT(0);		/* oprofile uses this */

EXPORT_SYMBOL(nmi_active);



static int nmi_init_done;

static unsigned int nmi_hz = HZ;

static DEFINE_PER_CPU(short, wd_enabled);

static int endflag __initdata;
@@ -153,6 +153,8 @@ static void report_broken_nmi(int cpu, int *prev_nmi_count) 


void stop_nmi_watchdog(void *unused)

{

	if (!__this_cpu_read(wd_enabled))

		return;

	pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);

	__this_cpu_write(wd_enabled, 0);

	atomic_dec(&nmi_active);
@@ -207,6 +209,9 @@ static int __init check_nmi_watchdog(void) 


void start_nmi_watchdog(void *unused)

{

	if (__this_cpu_read(wd_enabled))

		return;



	__this_cpu_write(wd_enabled, 1);

	atomic_inc(&nmi_active);
@@ -259,6 +264,8 @@ int __init nmi_init(void) 
		}

	}



	nmi_init_done = 1;



	return err;

}
@@ -270,3 +277,38 @@ static int __init setup_nmi_watchdog(char *str) 
	return 0;

}

__setup("nmi_watchdog=", setup_nmi_watchdog);



/*

 * sparc specific NMI watchdog enable function.

 * Enables watchdog if it is not enabled already.

 */

int watchdog_nmi_enable(unsigned int cpu)

{

	if (atomic_read(&nmi_active) == -1) {

		pr_warn("NMI watchdog cannot be enabled or disabled\n");

		return -1;

	}



	/*

	 * watchdog thread could start even before nmi_init is called.

	 * Just Return in that case. Let nmi_init finish the init

	 * process first.

	 */

	if (!nmi_init_done)

		return 0;



	smp_call_function_single(cpu, start_nmi_watchdog, NULL, 1);



	return 0;

}

/*

 * sparc specific NMI watchdog disable function.

 * Disables watchdog if it is not disabled already.

 */

void watchdog_nmi_disable(unsigned int cpu)

{

	if (atomic_read(&nmi_active) == -1)

		pr_warn_once("NMI watchdog cannot be enabled or disabled\n");

	else

		smp_call_function_single(cpu, stop_nmi_watchdog, NULL, 1);

}