Implement function update_arch_nmi_watchdog 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
specinf 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
Signed-off-by: Babu Moger <babu.mo...@oracle.com>
---
arch/sparc/kernel/nmi.c | 26 ++++++++++++++++++++++++++
1 files changed, 26 insertions(+), 0 deletions(-)
diff --git a/arch/sparc/kernel/nmi.c b/arch/sparc/kernel/nmi.c
index a9973bb..27c4e18 100644
--- a/arch/sparc/kernel/nmi.c
+++ b/arch/sparc/kernel/nmi.c
@@ -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 +209,8 @@ error:
void start_nmi_watchdog(void *unused)
{
+ if (__this_cpu_read(wd_enabled))
+ return;
__this_cpu_write(wd_enabled, 1);
atomic_inc(&nmi_active);
@@ -270,3 +274,25 @@ static int __init setup_nmi_watchdog(char *str)
return 0;
}
__setup("nmi_watchdog=", setup_nmi_watchdog);
+
+#ifdef CONFIG_LOCKUP_DETECTOR
+void update_arch_nmi_watchdog(void)
+{
+ if (atomic_read(&nmi_active) < 0) {
+ printk(KERN_WARNING
+ "NMI watchdog cannot be enabled or disabled\n");
+ return;
+ }
+
+ /*
+ * Check for bit 0. Bit 0 is dedicated for hard lockup detector or
+ * arch specific nmi and bit 1 for the soft lockup detector. We
+ * are interested only in bit 0 here.
+ */
+ if (watchdog_enabled & 1)
+ on_each_cpu(start_nmi_watchdog, NULL, 1);
+ else
+ on_each_cpu(stop_nmi_watchdog, NULL, 1);
+
+}
+#endif
--
1.7.1
