Userspace agent crash and kernel module

[Pranay Srivastava]

Hi Kevin,

Request you not to top post :-) .

> On Tue, Nov 18, 2014 at 10:15 AM, Pranay Srivastava <pranjas at gmail.com> wrote:
>> Hi Kevin
>>
>>
>>
>>
>> On Tue, Nov 18, 2014 at 1:19 PM, Kevin Wilson <wkevils at gmail.com> wrote:
>>> Hi,
>>> I want to write a kernel module which interacts with a userspace daemon.
>>> There are cases when the userspace daemon can terminate by some signals.
>>> There are also cases where the userspace daemon can crash (in some abnormal
>>> cases). Is there a way that the kernel module will be aware of such
>>> userspace agent crash, in order to reset its state ?
>>
>> Can't you reset it when the daemon is about to be killed from the
>> userspace itself? Depends on how complex/simple you want
>> this but there are several possibilities. Care to tell me how you
>> thought about doing this and where you got stuck?
>>
>>
>>>
>>> Regards,
>>> Kevin
>>>
>>> _______________________________________________
>>> Kernelnewbies mailing list
>>> Kernelnewbies at kernelnewbies.org
>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>>
>>
>> Regards
>> --
>>         ---P.K.S
>
>On Fri, Nov 21, 2014 at 4:25 PM, Kevin Wilson <wkevils at gmail.com> wrote:
> The thing is that crash of the daemon sometimes occur, from this
> reason or other.
> The question is how the kernel module will be aware of such
> userspace agent crash, in order to reset its state ?

I don't think kernel will know itself. The simplest you can do is put
a fault handler in userspace code
and have it do a write on a sysfs/procfs file or an ioctl or maybe
send signal or enqueue something
to another heartbeat daemon , etc, whatever method seems most
appropriate to you.

Does this sound useful?

>
> Regards,
> Kevin
>
>


-- 
        ---P.K.S