[Pvfs2-developers] bmi-tcp doubt

[Phil Carns]

Hi Ankur,

This patch fixes the code so that it does the right thing if you just 
return an error code from the tcp_accept_init() function.  It is already 
applied to cvs trunk.

thanks,
-Phil

Phil Carns wrote:
> For an immediate solution you can just mimic the logic in the "BIG 
> KLUDGE" comment block (where the trusted host/port check is similarly 
> discarding the request).  I was offering to fix that function so the 
> error handling works better, but it will be a few days.
> 
> -Phil
> 
> Pai, Ankur G wrote:
>> Disregarding the connection is fine with me. But what do I return
>> from bmi_tcp.c. If I return 0, the client call completes. If I return
>> -1, server crashes. So if I want to disregard the request, what do I
>> return from tcp_accept_init() ?
>>
>>
>> Thanks, Ankur ----- Original Message ----- From: "Phil Carns"
>> <carns at mcs.anl.gov> To: "Ankur G Pai" <paiankur at gatech.edu> Cc:
>> pvfs2-developers at beowulf-underground.org Sent: Thursday, November 20,
>> 2008 1:52:56 PM GMT -05:00 Columbia Subject: Re: [Pvfs2-developers]
>> bmi-tcp doubt
>>
>> The easiest thing would be to just discard the connection, but the 
>> downside is the client simply won't get a response back.  It would
>> just timeout and report "connection refused" instead.
>>
>> The error path needs to be cleaned up regardless, though.  Someone
>> else also ran into this in another context recently.  I'll look into
>> it and get a patch to you.
>>
>> -Phil
>>
>> Pai, Ankur G wrote:
>>> Hi Phil, All I want is the server not to crash and me not having to
>>>  take the request forward since I have already decided into not 
>>> servicing it. Could you suggest a reasonable approach?
>>>
>>> Thanks, Ankur ----- Original Message ----- From: "Phil Carns" 
>>> <carns at mcs.anl.gov> To: "Ankur G Pai" <paiankur at gatech.edu> Cc: 
>>> pvfs2-developers at beowulf-underground.org Sent: Thursday, November
>>> 20, 2008 10:07:44 AM GMT -05:00 Columbia Subject: Re:
>>> [Pvfs2-developers] bmi-tcp doubt
>>>
>>> Hi Ankur,
>>>
>>> I think we could clean up this path some.  Just to clarify what you
>>>  are looking for though, are you planning to send a response all
>>> the way back to the client?  The server does not normally send a
>>> response back for a failed unexpected message.  In the case you
>>> describe, you would need to propagate a specific error code out of 
>>> testunexpected(), and then add server state machine code to have it
>>>  identify that particular error code and send a response.
>>>
>>> Assuming that sounds like a reasonable approach, I'll look into 
>>> cleaning up the BMI part of that equation.
>>>
>>> -Phil
>>>
>>> Pai, Ankur G wrote:
>>>> Guys, I need some help. I am trying to change the function 
>>>> tcp_accept_init() inside src/io/bmi/bmi_tcp/bmi-tcp.c. This function 
>>>> has the accept() call (ie. it is the first point of contact by the 
>>>> pvfs client to the server). At this point I need
>>>> to make some immediate checks and decide if I want to allow this 
>>>> client any further access to the server. If I find out that I do NOT 
>>>> want to allow access I need to cleanly return an error to the
>>>>  client. If I do a return (-1) from this function, however, the 
>>>> server's bmi thread simply crashes giving me the foll output: 
>>>> ==================================================================================== 
>>>>
>>>>  [E 11/15 17:24] src/io/bmi/bmi.c line 957: Error: critical 
>>>> BMI_testcontext failure. [E 11/15 17:24]         [bt] 
>>>> pvfs2-server(BMI_testcontext+0x274) [0x807a344] [E 11/15 17:24] [bt] 
>>>> pvfs2-server [0x8072971] [E 11/15 17:24]         [bt] 
>>>> /lib/libpthread.so.0 [0xd4340b] [E 11/15 17:24]         [bt] 
>>>> /lib/libc.so.6(__clone+0x5e) [0xa03b7e] [E 11/15 17:24] Warning: non 
>>>> PVFS2 error code (1): [E 11/15 17:24] critical BMI failure. :
>>>>  Operation not permitted [E 11/15 17:24] bmi_thread_function
>>>> thread terminating [E 11/15 17:24] PVFS2 server got signal 2 
>>>> (server_status_flag: 262143) 
>>>> ====================================================================================== 
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> I am using pvfs-2.6.3. At this point in the code, i see a comment
>>>>  which says: 
>>>> ====================================================================================== 
>>>>
>>>>  /* FIXME: * BIG KLUDGE * if we return an error, pvfs2-server's
>>>> bmi thread simply terminates. * hence I am returning 0 here. Need
>>>> to ask Phil or RobR about this... */ 
>>>> ======================================================================================= 
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Is there any fix for this problem yet?
>>>>
>>>>
>>>
>>>
>>
>>
> 
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