linux-kernel - Re: [RFC PATCH 0/4] Clean up watchdog handlers

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Date:   Mon, 31 Oct 2016 17:00:57 -0400
From:   Don Zickus <dzickus@...hat.com>
To:     Babu Moger <babu.moger@...cle.com>
Cc:     mingo@...nel.org, akpm@...ux-foundation.org, ak@...ux.intel.com,
        jkosina@...e.cz, baiyaowei@...s.chinamobile.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, bp@...e.de,
        bywxiaobai@....com, cmetcalf@...lanox.com, keescook@...omium.org,
        ebiederm@...ssion.com, huawei.libin@...wei.com,
        ralf@...ux-mips.org, dvyukov@...gle.com,
        linux-kernel@...r.kernel.org, sam@...nborg.org
Subject: Re: [RFC PATCH 0/4] Clean up watchdog handlers

On Wed, Oct 26, 2016 at 09:02:19AM -0700, Babu Moger wrote:
> This is an attempt to cleanup watchdog handlers. Right now,
> kernel/watchdog.c implements both softlockup and hardlockup detectors.
> Softlockup code is generic. Hardlockup code is arch specific. Some
> architectures don't use hardlockup detectors. They use their own watchdog
> detectors. To make both these combination work, we have numerous #ifdefs
> in kernel/watchdog.c.
> 
> We are trying here to make these handlers independent of each other.
> Also provide an interface for architectures to implement their own
> handlers. watchdog_nmi_enable and watchdog_nmi_disable will be defined
> as weak such that architectures can override its definitions.
> 
> Thanks to Don Zickus for his suggestions.
> Here is the previous discussion
> http://www.spinics.net/lists/sparclinux/msg16441.html

Hi Babu,

I finally got some cycles to poke at this today.  Good work.  A couple of
suggestions.  For bisectability, I am thinking patch2 should be first and
patch1 and patch3 should be combined.  Also watchdog_hld.c is going to need
up top:

#define pr_fmt(fmt) "NMI watchdog: " fmt

otherwise the error messages miss the header.

Though I don't think watchdog.c and watchdog_hld.c should have the same
header.  A good solution isn't coming to me right now.  I will try to run
some tests on this tomorrow.


Cheers,
Don

> 
> Babu Moger (4):
>   watchdog: Remove hardlockup handler references
>   watchdog: Move shared definitions to nmi.h
>   watchdog: Move hardlockup detector in separate file
>   sparc: Implement watchdog_nmi_enable and watchdog_nmi_disable
> 
>  arch/sparc/kernel/nmi.c |   44 ++++++++-
>  include/linux/nmi.h     |   19 ++++
>  kernel/Makefile         |    1 +
>  kernel/watchdog.c       |  276 ++---------------------------------------------
>  kernel/watchdog_hld.c   |  238 ++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 312 insertions(+), 266 deletions(-)
>  create mode 100644 kernel/watchdog_hld.c
>