Re: [PATCH v5 bpf-next 02/11] tcp: Add num_closed_socks to struct sock_reuseport.

[Kuniyuki Iwashima]

From:   Martin KaFai Lau <kafai@xxxxxx>
Date:   Fri, 14 May 2021 17:49:18 -0700
> On Mon, May 10, 2021 at 12:44:24PM +0900, Kuniyuki Iwashima wrote:
> > As noted in the following commit, a closed listener has to hold the
> > reference to the reuseport group for socket migration. This patch adds a
> > field (num_closed_socks) to struct sock_reuseport to manage closed sockets
> > within the same reuseport group. Moreover, this and the following commits
> > introduce some helper functions to split socks[] into two sections and keep
> > TCP_LISTEN and TCP_CLOSE sockets in each section. Like a double-ended
> > queue, we will place TCP_LISTEN sockets from the front and TCP_CLOSE
> > sockets from the end.
> > 
> >   TCP_LISTEN---------->       <-------TCP_CLOSE
> >   +---+---+  ---  +---+  ---  +---+  ---  +---+
> >   | 0 | 1 |  ...  | i |  ...  | j |  ...  | k |
> >   +---+---+  ---  +---+  ---  +---+  ---  +---+
> > 
> >   i = num_socks - 1
> >   j = max_socks - num_closed_socks
> >   k = max_socks - 1
> > 
> > This patch also extends reuseport_add_sock() and reuseport_grow() to
> > support num_closed_socks.
> Acked-by: Martin KaFai Lau <kafai@xxxxxx>

Thank you!