linux-kernel - Re: SIGHUP on connect

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Date:   Thu, 29 Oct 2020 16:09:24 +0100
From:   "Michael J. Baars" <mjbaars1977.linux-kernel@...erfiber.eu>
To:     Bernd Petrovitsch <bernd@...rovitsch.priv.at>,
        linux-kernel@...r.kernel.org
Subject: Re: SIGHUP on connect

On Mon, 2020-10-26 at 17:12 +0000, Bernd Petrovitsch wrote:
> Hi all!
> 
> On 25/10/2020 16:11, Michael J. Baars wrote:
> [...]
> > I've been writing a simple client and server for cluster computing this weekend. At first everything appeared to work just fine, but soon enough I found
> > some
> > inexplicable bind errors. I've tried to make sure that the client closes it's sockets before the server closes it's sockets, to prevent linger, but trying
> > did
> 
> Which were exactly?
> English/original text pls ...
> 
> And The close() (and shutdown() syscalls, respectively) don't avoid
> the FIN_WAIT2 timeout on a closed socket.
> Just set the SO_REUSEADDR socket option on the listening socket.
> 
> > not help. Now I think I found the problem.
> 
> Then solve it.
> 
> > Please do have a look at the code. It looks like the SIGHUP is sent to the server not on close or exit, but on the connect instead.
> 
> Too lazy to save and uncompress the file ...
> 
> MfG,
> 	Bernd

Oh, I see the difference.

I forgot to mention that in my setup, there's only one client and numerous servers that do the computational work. So in my case, it would have been better to
have the SIGHUPs on sock[0]. In other cases, like most cases, the SIGHUPs should probably sent out on sock[1].

Best regards,
Mischa.