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

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Message-ID: <20161101132011.GW35881@redhat.com>
Date:   Tue, 1 Nov 2016 09:20:11 -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 Mon, Oct 31, 2016 at 04:30:59PM -0500, Babu Moger wrote:
> 
> On 10/31/2016 4:00 PM, Don Zickus wrote:
> >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.
> Don, Thanks for the feedback. Let me know if you run into problems with your
> tests.

Hi Babu,

My tests passed.  I just have to tweak the expected output lines as they
constantly change. :-(

I am going to play with different config options to see if things break from
a compile perspective.

> I will start working on the comments.

Great.

Cheers,
Don

> Thanks
> Babu
> 
> >
> >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
> >>
>