Re: [PATCH 1/2] watchdog: Introduce update_arch_nmi_watchdog

[Babu Moger]

On 10/6/2016 11:34 PM, Sam Ravnborg wrote:

On Thu, Oct 06, 2016 at 03:16:42PM -0700, Babu Moger wrote:

Currently we do not have a way to enable/disable arch specific
watchdog handlers if it was implemented by any of the architectures.

This patch introduces new function update_arch_nmi_watchdog
which can be used to enable/disable architecture specific NMI
watchdog handlers. Also exposes watchdog_enabled variable outside
so that arch specific nmi watchdogs can use it to implement
enalbe/disable behavour.

Signed-off-by: Babu Moger 
---
  include/linux/nmi.h |1 +
  kernel/watchdog.c   |   16 +---
  2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 4630eea..01b4830 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -66,6 +66,7 @@ static inline bool trigger_allbutself_cpu_backtrace(void)
  
  #ifdef CONFIG_LOCKUP_DETECTOR

  u64 hw_nmi_get_sample_period(int watchdog_thresh);
+extern unsigned long watchdog_enabled;

The extern is within an #ifdef, but the definition later is
valid alway.
So extern definition should be outside the #ifdef to match the
actual implementation.


 Ok. Sure.



To manipulate / read watchdog_enabled two constants are used:
NMI_WATCHDOG_ENABLED, SOFT_WATCHDOG_ENABLED


Sure. I will bring these definitions to nmi.h from watchdog.c


They should be visible too, so uses do not fall into the trap
and uses constants (like in patch 2).


Will re-post v2 version with these changes. Thanks for the comments.



Sam

Re: [PATCH 1/2] watchdog: Introduce update_arch_nmi_watchdog

[Babu Moger]

On 10/6/2016 11:34 PM, Sam Ravnborg wrote:

On Thu, Oct 06, 2016 at 03:16:42PM -0700, Babu Moger wrote:

Currently we do not have a way to enable/disable arch specific
watchdog handlers if it was implemented by any of the architectures.

This patch introduces new function update_arch_nmi_watchdog
which can be used to enable/disable architecture specific NMI
watchdog handlers. Also exposes watchdog_enabled variable outside
so that arch specific nmi watchdogs can use it to implement
enalbe/disable behavour.

Signed-off-by: Babu Moger 
---
  include/linux/nmi.h |1 +
  kernel/watchdog.c   |   16 +---
  2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 4630eea..01b4830 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -66,6 +66,7 @@ static inline bool trigger_allbutself_cpu_backtrace(void)
  
  #ifdef CONFIG_LOCKUP_DETECTOR

  u64 hw_nmi_get_sample_period(int watchdog_thresh);
+extern unsigned long watchdog_enabled;

The extern is within an #ifdef, but the definition later is
valid alway.
So extern definition should be outside the #ifdef to match the
actual implementation.


 Ok. Sure.



To manipulate / read watchdog_enabled two constants are used:
NMI_WATCHDOG_ENABLED, SOFT_WATCHDOG_ENABLED


Sure. I will bring these definitions to nmi.h from watchdog.c


They should be visible too, so uses do not fall into the trap
and uses constants (like in patch 2).


Will re-post v2 version with these changes. Thanks for the comments.



Sam

Re: [PATCH 1/2] watchdog: Introduce update_arch_nmi_watchdog

[Sam Ravnborg]

On Thu, Oct 06, 2016 at 03:16:42PM -0700, Babu Moger wrote:
> Currently we do not have a way to enable/disable arch specific
> watchdog handlers if it was implemented by any of the architectures.
> 
> This patch introduces new function update_arch_nmi_watchdog
> which can be used to enable/disable architecture specific NMI
> watchdog handlers. Also exposes watchdog_enabled variable outside
> so that arch specific nmi watchdogs can use it to implement
> enalbe/disable behavour.
> 
> Signed-off-by: Babu Moger 
> ---
>  include/linux/nmi.h |1 +
>  kernel/watchdog.c   |   16 +---
>  2 files changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/nmi.h b/include/linux/nmi.h
> index 4630eea..01b4830 100644
> --- a/include/linux/nmi.h
> +++ b/include/linux/nmi.h
> @@ -66,6 +66,7 @@ static inline bool trigger_allbutself_cpu_backtrace(void)
>  
>  #ifdef CONFIG_LOCKUP_DETECTOR
>  u64 hw_nmi_get_sample_period(int watchdog_thresh);
> +extern unsigned long watchdog_enabled;

The extern is within an #ifdef, but the definition later is
valid alway.
So extern definition should be outside the #ifdef to match the
actual implementation.

To manipulate / read watchdog_enabled two constants are used: 
NMI_WATCHDOG_ENABLED, SOFT_WATCHDOG_ENABLED

They should be visible too, so uses do not fall into the trap
and uses constants (like in patch 2).

Sam

Re: [PATCH 1/2] watchdog: Introduce update_arch_nmi_watchdog

[Sam Ravnborg]

On Thu, Oct 06, 2016 at 03:16:42PM -0700, Babu Moger wrote:
> Currently we do not have a way to enable/disable arch specific
> watchdog handlers if it was implemented by any of the architectures.
> 
> This patch introduces new function update_arch_nmi_watchdog
> which can be used to enable/disable architecture specific NMI
> watchdog handlers. Also exposes watchdog_enabled variable outside
> so that arch specific nmi watchdogs can use it to implement
> enalbe/disable behavour.
> 
> Signed-off-by: Babu Moger 
> ---
>  include/linux/nmi.h |1 +
>  kernel/watchdog.c   |   16 +---
>  2 files changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/nmi.h b/include/linux/nmi.h
> index 4630eea..01b4830 100644
> --- a/include/linux/nmi.h
> +++ b/include/linux/nmi.h
> @@ -66,6 +66,7 @@ static inline bool trigger_allbutself_cpu_backtrace(void)
>  
>  #ifdef CONFIG_LOCKUP_DETECTOR
>  u64 hw_nmi_get_sample_period(int watchdog_thresh);
> +extern unsigned long watchdog_enabled;

The extern is within an #ifdef, but the definition later is
valid alway.
So extern definition should be outside the #ifdef to match the
actual implementation.

To manipulate / read watchdog_enabled two constants are used: 
NMI_WATCHDOG_ENABLED, SOFT_WATCHDOG_ENABLED

They should be visible too, so uses do not fall into the trap
and uses constants (like in patch 2).

Sam

[PATCH 1/2] watchdog: Introduce update_arch_nmi_watchdog

[Babu Moger]

Currently we do not have a way to enable/disable arch specific
watchdog handlers if it was implemented by any of the architectures.

This patch introduces new function update_arch_nmi_watchdog
which can be used to enable/disable architecture specific NMI
watchdog handlers. Also exposes watchdog_enabled variable outside
so that arch specific nmi watchdogs can use it to implement
enalbe/disable behavour.

Signed-off-by: Babu Moger 
---
 include/linux/nmi.h |1 +
 kernel/watchdog.c   |   16 +---
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 4630eea..01b4830 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -66,6 +66,7 @@ static inline bool trigger_allbutself_cpu_backtrace(void)
 
 #ifdef CONFIG_LOCKUP_DETECTOR
 u64 hw_nmi_get_sample_period(int watchdog_thresh);
+extern unsigned long watchdog_enabled;
 extern int nmi_watchdog_enabled;
 extern int soft_watchdog_enabled;
 extern int watchdog_user_enabled;
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 9acb29f..1ac2814 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -46,16 +46,21 @@
 
 static DEFINE_MUTEX(watchdog_proc_mutex);
 
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
-static unsigned long __read_mostly watchdog_enabled = 
SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED;
+#if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG)
+unsigned long __read_mostly watchdog_enabled = 
SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED;
 #else
-static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED;
+unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED;
 #endif
 int __read_mostly nmi_watchdog_enabled;
 int __read_mostly soft_watchdog_enabled;
 int __read_mostly watchdog_user_enabled;
 int __read_mostly watchdog_thresh = 10;
 
+/*
+ * Implemented by arch specific handlers if it defines CONFIG_HAVE_NMI_WATCHDOG
+ */
+void __weak update_arch_nmi_watchdog(void) {}
+
 #ifdef CONFIG_SMP
 int __read_mostly sysctl_softlockup_all_cpu_backtrace;
 int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
@@ -842,6 +847,11 @@ static int proc_watchdog_update(void)
int err = 0;
 
/*
+* Enable/Disable arch specific nmi watchdogs if there is one
+*/
+   update_arch_nmi_watchdog();
+
+   /*
 * Watchdog threads won't be started if they are already active.
 * The 'watchdog_running' variable in watchdog_*_all_cpus() takes
 * care of this. If those threads are already active, the sample
-- 
1.7.1

[PATCH 1/2] watchdog: Introduce update_arch_nmi_watchdog

[Babu Moger]

Currently we do not have a way to enable/disable arch specific
watchdog handlers if it was implemented by any of the architectures.

This patch introduces new function update_arch_nmi_watchdog
which can be used to enable/disable architecture specific NMI
watchdog handlers. Also exposes watchdog_enabled variable outside
so that arch specific nmi watchdogs can use it to implement
enalbe/disable behavour.

Signed-off-by: Babu Moger 
---
 include/linux/nmi.h |1 +
 kernel/watchdog.c   |   16 +---
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 4630eea..01b4830 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -66,6 +66,7 @@ static inline bool trigger_allbutself_cpu_backtrace(void)
 
 #ifdef CONFIG_LOCKUP_DETECTOR
 u64 hw_nmi_get_sample_period(int watchdog_thresh);
+extern unsigned long watchdog_enabled;
 extern int nmi_watchdog_enabled;
 extern int soft_watchdog_enabled;
 extern int watchdog_user_enabled;
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 9acb29f..1ac2814 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -46,16 +46,21 @@
 
 static DEFINE_MUTEX(watchdog_proc_mutex);
 
-#ifdef CONFIG_HARDLOCKUP_DETECTOR
-static unsigned long __read_mostly watchdog_enabled = 
SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED;
+#if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG)
+unsigned long __read_mostly watchdog_enabled = 
SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED;
 #else
-static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED;
+unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED;
 #endif
 int __read_mostly nmi_watchdog_enabled;
 int __read_mostly soft_watchdog_enabled;
 int __read_mostly watchdog_user_enabled;
 int __read_mostly watchdog_thresh = 10;
 
+/*
+ * Implemented by arch specific handlers if it defines CONFIG_HAVE_NMI_WATCHDOG
+ */
+void __weak update_arch_nmi_watchdog(void) {}
+
 #ifdef CONFIG_SMP
 int __read_mostly sysctl_softlockup_all_cpu_backtrace;
 int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
@@ -842,6 +847,11 @@ static int proc_watchdog_update(void)
int err = 0;
 
/*
+* Enable/Disable arch specific nmi watchdogs if there is one
+*/
+   update_arch_nmi_watchdog();
+
+   /*
 * Watchdog threads won't be started if they are already active.
 * The 'watchdog_running' variable in watchdog_*_all_cpus() takes
 * care of this. If those threads are already active, the sample
-- 
1.7.1