netdev - Re: Why ECONNREFUSED from unix_dgram

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Date:	Thu, 11 Sep 2014 10:52:04 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc:	Network Development <netdev@...r.kernel.org>
Subject: Re: Why ECONNREFUSED from unix_dgram_sendmsg?

On Sep 11, 2014 8:59 AM, "Hannes Frederic Sowa"
<hannes@...essinduktion.org> wrote:
>
>
>
> On Thu, Sep 11, 2014, at 17:11, Andy Lutomirski wrote:
> > What is unix_dgram_sendmsg trying to tell me here?
> >
> >         if (sock_flag(other, SOCK_DEAD)) {
> >                 /*
> >                  *      Check with 1003.1g - what should
> >                  *      datagram error
> >                  */
> >                 unix_state_unlock(other);
> >                 sock_put(other);
> >
> >                 err = 0;
> >                 unix_state_lock(sk);
> >                 if (unix_peer(sk) == other) {
> >                         unix_peer(sk) = NULL;
> >                         unix_state_unlock(sk);
> >
> >                         unix_dgram_disconnected(sk, other);
> >                         sock_put(other);
> >                         err = -ECONNREFUSED;
> >
> > I'm getting this intermittently on a seqpacket socket when the other
> > end dies.  Shouldn't this be -ECONNRESET?
> >
> > git blame doesn't tell me anything here -- this code predates git.
>
> Changelogs were not that descriptive as they were today: :)
>
> commit 283fd6cf0be690a83b5dbb34e79130f8592c0765
> Author: davem <davem>
> Date:   Fri Aug 20 10:59:51 1999 +0000
>
>     Merge in ANK networking jumbo patch,
>     which includes ATM from Werner Almesberger, Netfilter
>     from Paul Russell, and massive SMP networking enhancements
>     by Alexey.
>
> (in
> https://git.kernel.org/cgit/linux/kernel/git/davem/netdev-vger-cvs.git/)
>
> I agree, -ECONNRESET would be a better errno value, but this is hard to
> change because of backwards compatibility.

Might it be safe to change it for just seqpacket sockets?  -ECONRESET
actually makes some sense for dgram sockets, assuming this code is
even reachable for dgram sockets.

Anyway, I'll have to fix my code regardless.

--Andy
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