Re: [Xenomai] rtnet locking/socket SKBs

["Marc Strämke" <marc.straemke@eltropuls.de>]

Gilles,

Am Donnerstag, 4. Juni 2015, 12:56:16 schrieb Gilles Chanteperdrix:
> The previous rtnet design was converted to reference counts globally
> when integrating into xenomai 3, some details may still need fixing.
> The old design was different but lead to the close syscall looping
> for ever and blocking your application if anything went wrong, so,
> this is an attempt to avoid this issue.
Yes I do understand this. I am just trying to figure out what the right fix is. 
If I just disable incrementing the fd reference count (see attached patch) 
AF_PACKET works as it should.  From my current understanding of the code the 
reference counting for the SKB Pools attached to a socket is redundant, but 
I've only closely inspected AF_PACKET not the other sockets in the IP stack.

> 
> > They will never get cleared if the application crashes If I am
> > not mistaken.
> 
> Once again: when an application crashes, the file descriptors are
> automatically closed by Xenomai, you do not need to care about this
> case.
What I am seeing is that when the reference count is above 1 when the 
application closes/crashes, the close operation of the rtdm socket never get's 
called, neither when doing an explicit close system call on the socket which 
still had a reference count above 1.

When I disable the skb pool reference counting for AF_PACKET it basically 
works as it should. When the application closes the socket or crashes the 
close op get's called and the skb's release. 

Marc

-- 
Dipl.-Ing. Marc Strämke
Geschäftsführer / CEO

ELTROPULS Anlagenbau GmbH
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