[Pvfs2-developers] patches: misc. bug fixes

[Sam Lang]

Hi Murali,

Thanks for commenting on this.  I lost track of these patches  
somehow.  I agree that they look good, so I went ahead and commited  
them.  Thanks Phil!

-sam

On Apr 5, 2007, at 7:57 AM, Phil Carns wrote:

> Murali Vilayannur wrote:
>> Hi Phil,
>> FWIW, if these patches haven't been committed, it looks good :)
>> I am really backlogged with all my emails.
>>> auto-sm-tracking.patch:
>>> -----------------------
>>> At some point, new linked lists were added to track state  
>>> machines that
>>> are currently running within the server.  When an SM completes,  
>>> it is
>>> implicitly removed from the list.  However, SMs that were started
>>> without a request (ie internal state machines) were not added to any
>>> list.  This caused a segfault if any of these internal state  
>>> machines
>>> stopped (because the completion code assumes that all SMs should be
>>> removed from a list).  This patch corrects the problem by just  
>>> making an
>>> extra linked list for state machine instances that are not  
>>> associated
>>> with a particular request.
>> Just curious: why/how did the internal state machine stop? I recall
>> asking Sam this
>> question when I added those lists and he mentioned that they  
>> shouldn't
>> stop unless the server was being terminated. The only place where I
>> thought the sm structure was being removed from the list was in
>> server_state_machine_complete() which is invoked on state machines
>> invoked via a request.
>> Or perhaps I misunderstood what he said :)
>> thanks,
>> Murali
>
> Hi Murali,
>
> I don't think that it is normal for the standard internal state  
> machines to stop, but there isn't any mechanism to explicitly  
> prevent it.  Both the perf-update and job-timer state machines have  
> transitions defined to terminate if something bad happens.  Those  
> state functions call server_state_machine_complete() in the usual  
> way to clean themselves up.
>
> We saw it happen on a different internal state machine that we were  
> experimenting with.  We didn't expect that particular one to stop  
> either, but it did due to an unrelated bug.  This list issue was  
> just a helpful thing to clean up along the way.
>
> -Phil
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