Re: [PATCH 10/11] contrib: Add program to document and test assumptions about SO_REUSEADDR

[Stefano Brivio <sbrivio@redhat.com>]

On Fri, 5 Jul 2024 10:06:12 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Thu, Jul 04, 2024 at 11:21:21PM +0200, Stefano Brivio wrote:
> > On Thu,  4 Jul 2024 14:58:34 +1000
> > David Gibson <david@gibson.dropbear.id.au> wrote:
> >   
> > > For the approach we intend to use for handling UDP flows, we have some
> > > pretty specific requirements about how SO_REUSEADDR works with UDP sockets.
> > > Specifically SO_REUSEADDR allows multiple sockets with overlapping bind()s,
> > > and therefore there can be multiple sockets which are eligible to receive
> > > the same datagram.  Which one will actually receive it is important to us.
> > > 
> > > Add a test program which verifies things work the way we expect, which
> > > documents what those expectations are in the process.
> > > 
> > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > > ---
> > >  contrib/udp-behaviour/.gitignore           |   1 +
> > >  contrib/udp-behaviour/Makefile             |  45 ++++
> > >  contrib/udp-behaviour/common.c             |  66 ++++++
> > >  contrib/udp-behaviour/common.h             |  47 ++++
> > >  contrib/udp-behaviour/reuseaddr-priority.c | 240 +++++++++++++++++++++
> > >  5 files changed, 399 insertions(+)  
> > 
> > I reviewed these (10/11 and 11/11) a bit lightly, but they look sane to
> > me. I just wonder: wouldn't it be better to have
> > contrib/linux/udp-behaviour instead, so that it's consistent with the
> > other stuff unter contrib/ (project names, kind of)?  
> 
> Well.. if we ever port to something non-Linux, we'll need the same
> socket behaviour there.  Indeed, that's one reason I think having
> these test programs is valuable.  So I don't think 'linux/' is a great
> pick.

Oh, oops, I thought SO_REUSEADDR were specific to Linux, that's why I
was suggesting linux/, but it's actually supported by all the BSDs.

> In some ways contrib/ isn't really the right place for this.  Maybe
> it would be better under doc/?  But at the moment that's more user
> facing than developer facing documentation.

I would still say it's documentation and it can happily fit under doc/.
Distribution packages don't copy the whole doc/ (to /usr/share/doc/)
anyway.

Or test/kernel/? But it's not something we want to check regularly,
it's really an example to help with development.

All in all, I don't have a strong preference, doc/ looks like a better
fit to me, but contrib/ isn't problematic either.

-- 
Stefano