[patch] add kdump_after_notifier

[Takenori Nagano]

Hi all,

I finished to implement this function. I will send patches after this mail.
Please review them and give some comments.

Thanks,

Jay Lan wrote:
> Vivek Goyal wrote:
>> On Tue, Aug 21, 2007 at 06:18:31AM -0700, Jay Lan wrote:
>> [..]
>>>>>> Now user will be able to view all the die_chain users through sysfs and
>>>>>> be able to modify the order in which these should run by modifying their
>>>>>> priority. Hence all the RAS tools can co-exist.
>>>>> This is my image of your proposal.
>>>>>
>>>>> - Print current order
>>>>>
>>>>> # cat /sys/class/misc/debug/panic_notifier_list
>>>>> priority   name
>>>>> 1          IPMI
>>>>> 2          watchdog
>>>>> 3          Kdb
>>>>> 4          Kdump
>>>>>
>>>> I think Bernhard's suggestion looks better here. I noticed that 
>>>> /sys/kernel/debug is already present. So how about following.
>>>>
>>>> /sys/kernel/debug/kdump/priority
>>>> /sys/kernel/debug/kdb/priority
>>>> /sys/kernel/debug/IPMI/priority
>>> Why separate priority files is better than a central file?
>>> At least i think you get a grand picture of priority being
>>> defined for all parties with a central file?
>>>
>> I thought of couple of reasons.
>> - A very different syntax to modify the priority.
>> - Separate directories allow easy future extensions in terms of more
>>   files. For example, putting a small "description" file in each dir
>>   where each registered user can specify what does it do.
> 
> The first can be easily resolved by providing a comment section in the
> file with real examples. Users can simply uncomment a line to activate.
> But future expansion is certainly is a good reason for this layout.
> 
>> But I agree that a single file is good for consolidated view. As bernhard
>> suggested, may be we should also implement a read only file where one
>> will get a consolidated view.
> 
> Yep, this will help!
> 
>>> What do we decide priority if more than one component has
>>> the same priority value?
>>>
>> I think first come first serve would be appropriate in this case instead of
>> returning -EINVAL.
> 
> How does the kernel process the configuration files? By alphabetic order
> of the filename? Either way, i think a clear failure/warning dmesg is
> very important.
> 
> Thanks,
>  - jay
> 
>> Thanks
>> Vivek
>>
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> 
>