Closing a socket.

[Joel Sherrill <joel@OARcorp.com>]

Chris Johns wrote:
> Thomas Rauscher wrote:
> 
>>
>> Maybe there is a race condition (visual check against 4.6.2).
>> Please correct me if I'm wrong.
> 
> 
> Yes there is a problem here.
> 
>>
>> If rtems_bsdnet_close is called, the socket is freed in
>> soclose (depends on socket state, protocol used, ...).
>> The waiting thread might wake up later (depends on
>> scheduling) and could access so->so_pgid in soconnsleep().
>> Bad things would happen if this memory area is now used for something 
>> else...
>> I remember having seen this in an accept/close race
>> (rtems 4.5).
> 
> 
> It looks to me like a bug in accept which I am looking at.

Where is the code you are looking at?  I want to peek.

>> A clean (and portable) way is to send a "QUIT" message to the socket 
>> so that the blocking
>> thread can stop using the socket.
>>
> 
> What do you mean by a "QUIT" message ? Is this a way to have soconnwake 
> and friends called ? If so a standard close on a socket fd does this.
> 
>> TCP connections can be closed with shutdown().
> 
> 
> Is this a TCP socket shutdown or an RTEMS shutdown ?
> 


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Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
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