linux-kernel - Re: [PATCH 1/2] watchdog: Introduce update_arch_nmi

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Message-ID: <8ea9198e-1407-12ba-2909-ded6e8ec5eb0@oracle.com>
Date:   Fri, 7 Oct 2016 09:54:16 -0500
From:   Babu Moger <babu.moger@...cle.com>
To:     Sam Ravnborg <sam@...nborg.org>
Cc:     mingo@...nel.org, akpm@...ux-foundation.org, ak@...ux.intel.com,
        jkosina@...e.cz, baiyaowei@...s.chinamobile.com,
        dzickus@...hat.com, atomlin@...hat.com, uobergfe@...hat.com,
        tj@...nel.org, hidehiro.kawai.ez@...achi.com, johunt@...mai.com,
        davem@...emloft.net, sparclinux@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] watchdog: Introduce update_arch_nmi_watchdog


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 <babu.moger@...cle.com>
>> ---
>>   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