[PATCH v2 2/2] sparc: Implement arch_watchdog_nmi_enable and arch_watchdog_nmi_disable

[Babu Moger]

Implement functions arch_watchdog_nmi_enable and arch_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

Signed-off-by: Babu Moger 
---
 arch/sparc/kernel/nmi.c |   41 -
 1 files changed, 40 insertions(+), 1 deletions(-)

diff --git a/arch/sparc/kernel/nmi.c b/arch/sparc/kernel/nmi.c
index a9973bb..d7e2c01 100644
--- a/arch/sparc/kernel/nmi.c
+++ b/arch/sparc/kernel/nmi.c
@@ -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(_active);
@@ -207,6 +209,9 @@ error:
 
 void start_nmi_watchdog(void *unused)
 {
+   if (__this_cpu_read(wd_enabled))
+   return;
+
__this_cpu_write(wd_enabled, 1);
atomic_inc(_active);
 
@@ -259,6 +264,8 @@ int __init nmi_init(void)
}
}
 
+   nmi_init_done = 1;
+
return err;
 }
 
@@ -270,3 +277,35 @@ 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 arch_watchdog_nmi_enable(unsigned int cpu)
+{
+   if (atomic_read(_active) == -1) {
+   pr_info_once("NMI watchdog cannot be enabled\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 arch_watchdog_nmi_disable(unsigned int cpu)
+{
+   smp_call_function_single(cpu, stop_nmi_watchdog, NULL, 1);
+}
-- 
1.7.1

[PATCH v2 2/2] sparc: Implement arch_watchdog_nmi_enable and arch_watchdog_nmi_disable

[Babu Moger]

Implement functions arch_watchdog_nmi_enable and arch_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

Signed-off-by: Babu Moger 
---
 arch/sparc/kernel/nmi.c |   41 -
 1 files changed, 40 insertions(+), 1 deletions(-)

diff --git a/arch/sparc/kernel/nmi.c b/arch/sparc/kernel/nmi.c
index a9973bb..d7e2c01 100644
--- a/arch/sparc/kernel/nmi.c
+++ b/arch/sparc/kernel/nmi.c
@@ -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(_active);
@@ -207,6 +209,9 @@ error:
 
 void start_nmi_watchdog(void *unused)
 {
+   if (__this_cpu_read(wd_enabled))
+   return;
+
__this_cpu_write(wd_enabled, 1);
atomic_inc(_active);
 
@@ -259,6 +264,8 @@ int __init nmi_init(void)
}
}
 
+   nmi_init_done = 1;
+
return err;
 }
 
@@ -270,3 +277,35 @@ 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 arch_watchdog_nmi_enable(unsigned int cpu)
+{
+   if (atomic_read(_active) == -1) {
+   pr_info_once("NMI watchdog cannot be enabled\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 arch_watchdog_nmi_disable(unsigned int cpu)
+{
+   smp_call_function_single(cpu, stop_nmi_watchdog, NULL, 1);
+}
-- 
1.7.1