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* [PATCH] V2 init/main.c Enable watchdog_thresh control from kernel line
@ 2018-10-24 15:53 Laurence Oberman
  2018-10-24 16:19 ` Randy Dunlap
  0 siblings, 1 reply; 2+ messages in thread
From: Laurence Oberman @ 2018-10-24 15:53 UTC (permalink / raw)
  To: linux-kernel, loberman; +Cc: rdunlap

Both graphics and serial consoles are exposed to hard lockups
when handling a large amount of messaging. The kernel watchdog_thresh
parameter up to now has not been available to be set on the kernel line for
early boot. 
This patch allows the setting of watchdog_thresh to be increased
when needed to avoid the hard lockups in the console code.

Signed-off-by: Laurence Oberman <loberman@redhat.com>
---
 init/main.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/init/main.c b/init/main.c
index e4a3160..5882750 100644
--- a/init/main.c
+++ b/init/main.c
@@ -977,6 +977,15 @@ static int __init set_debug_rodata(char *str)
 __setup("rodata=", set_debug_rodata);
 #endif
 
+static int __init
+is_watchdog_thresh_setup(char *str)
+{
+	get_option(&str, &watchdog_thresh);
+	return 1;
+}
+__setup("watchdog_thresh=", is_watchdog_thresh_setup);
+
+
 #ifdef CONFIG_STRICT_KERNEL_RWX
 static void mark_readonly(void)
 {
-- 
1.8.3.1

---
 Documentation/admin-guide/kernel-parameters.txt | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index bf03fe4..a5280a1 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4615,6 +4615,14 @@
 			or other driver-specific files in the
 			Documentation/watchdog/ directory.
 
+	watchdog_thresh=
+			This parameter is now available as a kernel line
+			parameter. Use watchdog_thresh=30 as example
+			This will allow early boot changes of the current
+			default of 10s to be increased when needed to
+			avoid hard lockups.
+			Default: 10
+
 	workqueue.watchdog_thresh=
 			If CONFIG_WQ_WATCHDOG is configured, workqueue can
 			warn stall conditions and dump internal state to
-- 
1.8.3.1


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH] V2 init/main.c Enable watchdog_thresh control from kernel line
  2018-10-24 15:53 [PATCH] V2 init/main.c Enable watchdog_thresh control from kernel line Laurence Oberman
@ 2018-10-24 16:19 ` Randy Dunlap
  0 siblings, 0 replies; 2+ messages in thread
From: Randy Dunlap @ 2018-10-24 16:19 UTC (permalink / raw)
  To: Laurence Oberman, linux-kernel

On 10/24/18 8:53 AM, Laurence Oberman wrote:
> Both graphics and serial consoles are exposed to hard lockups
> when handling a large amount of messaging. The kernel watchdog_thresh
> parameter up to now has not been available to be set on the kernel line for
> early boot. 
> This patch allows the setting of watchdog_thresh to be increased
> when needed to avoid the hard lockups in the console code.
> 
> Signed-off-by: Laurence Oberman <loberman@redhat.com>
> ---
>  init/main.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/init/main.c b/init/main.c
> index e4a3160..5882750 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -977,6 +977,15 @@ static int __init set_debug_rodata(char *str)
>  __setup("rodata=", set_debug_rodata);
>  #endif
>  
> +static int __init
> +is_watchdog_thresh_setup(char *str)
> +{
> +	get_option(&str, &watchdog_thresh);
> +	return 1;
> +}
> +__setup("watchdog_thresh=", is_watchdog_thresh_setup);
> +
> +
>  #ifdef CONFIG_STRICT_KERNEL_RWX
>  static void mark_readonly(void)
>  {
> 

Hi Laurence,

Let's make this into more of a complete patch.

a.  update the diffstat to include the Documentation change

b.  send the patch with the Documentation change as part of the same patch,
not as a separate patch (It looks like the multiple "---" lines in the
email are confusing.)

c.  send the patch to someone who can merge it: scripts/get_maintainer.pl top
suggestions are:
Thomas Gleixner <tglx@linutronix.de> or Ingo Molnar <mingo@kernel.org>

thanks,
-- 
~Randy

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2018-10-24 15:53 [PATCH] V2 init/main.c Enable watchdog_thresh control from kernel line Laurence Oberman
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