Re: [PATCH bpf-next v1 2/5] af_unix: add unix_stream_proto for sockmap

[John Fastabend]

Cong Wang wrote:
> On Wed, Jul 28, 2021 at 11:44 AM John Fastabend
> <john.fastabend@xxxxxxxxx> wrote:
> >
> > Cong Wang wrote:
> > > On Tue, Jul 27, 2021 at 9:37 AM John Fastabend <john.fastabend@xxxxxxxxx> wrote:
> > > > Do we really need an unhash hook for unix_stream? I'm doing some testing
> > > > now to pull it out of TCP side as well. It seems to be an artifact of old
> > > > code that is no longer necessary. On TCP side at least just using close()
> > > > looks to be enough now.
> > >
> > > How do you handle the disconnection from remote without ->unhash()?
> >
> > Would close() not work for stream/dgram sockets?
> 
> close() is called when the local closes the sockets, but when the remote
> closes or disconnects it, unhash() is called. This is why TCP calls unhash()
> to remove the socket from established socket hash table. unhash() itself
> might not make much sense for AF_UNIX as it probably does not need a
> hash table to track established ones, however, the idea is the same, that
> is, we have to handle remote disconnections here.

Following up on this series. Leaving a socket in the sockmap until close()
happens is not paticularly problematic, but does consume space in the map
so unhash() is slightly better I guess. Thanks.

> 
> Thanks.