linux-kernel - Re: [PATCH v2 0/3] Clean up watchdog handlers

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Message-ID: <3080c0f9-7ef1-0c0f-dcc2-97c356220c3a@oracle.com>
Date:   Fri, 4 Nov 2016 11:52:57 -0500
From:   Babu Moger <babu.moger@...cle.com>
To:     Don Zickus <dzickus@...hat.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,
        linux-kernel@...r.kernel.org, sam@...nborg.org
Subject: Re: [PATCH v2 0/3] Clean up watchdog handlers


On 11/4/2016 11:25 AM, Don Zickus wrote:
> On Tue, Nov 01, 2016 at 02:13:43PM -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 are our previous discussions
>> http://www.spinics.net/lists/sparclinux/msg16543.html
>> http://www.spinics.net/lists/sparclinux/msg16441.html
>>
> Hi Babu,
>
> Thanks for the patches.  It passes my panic/reboot testing.  The patches
> look good for now.  Though this change has me thinking about other cleanup
> changes I can make on top of this.  But I am going to hold off for now until
> we are sure nothing really broke.  As this should be a straight forward
> split.
>
> The only odd thing for me is I am having trouble disabling
> CONFIG_HARDLOCKUP_DETECTOR.  For some reason def_bool y, is forcing the
> option on despite my repeated attempts to disable it.  I had to rename the
> option to do some test compiling and verify it doesn't regress when
> disabled.  Probably my environment..

   Don, You are welcome. Thanks for your feedback to resolve this.

>
> Thanks for the work Babu!
>
> Acked-by: Don Zickus <dzickus@...hat.com>
>
>
>> v2:
>>    Addressed few comments from Don Zickus.
>>    1. Took care of bisectability issue. Previous patch2 is patch1 now.
>>       Combined patch 1 and 3. Patch 4 is now patch 3.
>>    2. Added pr_fmt back in watchdog_hld.c
>>    3. Tweaked the file headers for watchdog.c and watchdog_hld.c.
>>
>>    4. Took care of couple of config compile issues.
>>
>>     drivers/edac/edac_device.o:(.discard+0x0): multiple definition of `__pcpu_unique_hrtimer_interrupts'
>>     drivers/edac/edac_mc.o:(.discard+0x0): first defined here
>>     This was a problem with uni processor config. Moved the definition of hrtimer_interrupts and
>>     is_hardlockup into watchdog.c as softlockup code does most of the work here.
>>     is_hardlockup kind of generic most part.
>>
>>     kernel/built-in.o: In function `watchdog_overflow_callback':
>>     watchdog_hld.c:(.text+0x56940): undefined reference to `sysctl_hardlockup_all_cpu_backtrace'
>>     Moved this definition to nmi.h.
>>
>> v1:
>>    Initial version
>> Babu Moger (3):
>>    watchdog: Move shared definitions to nmi.h
>>    watchdog: Move hardlockup detector to separate file
>>    sparc: Implement watchdog_nmi_enable and watchdog_nmi_disable
>>
>>   arch/sparc/kernel/nmi.c |   44 ++++++++-
>>   include/linux/nmi.h     |   24 ++++
>>   kernel/Makefile         |    1 +
>>   kernel/watchdog.c       |  270 +++--------------------------------------------
>>   kernel/watchdog_hld.c   |  227 +++++++++++++++++++++++++++++++++++++++
>>   5 files changed, 310 insertions(+), 256 deletions(-)
>>   create mode 100644 kernel/watchdog_hld.c
>>