Re: [PATCH 6/8] udp: Unify udp_sock_handler_splice() with udp_sock_handler()

[Stefano Brivio <sbrivio@redhat.com>]

On Wed, 14 Dec 2022 12:19:14 +1100
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Tue, Dec 13, 2022 at 11:48:58PM +0100, Stefano Brivio wrote:
> > On Mon,  5 Dec 2022 19:14:23 +1100
> > David Gibson <david@gibson.dropbear.id.au> wrote:
> >   
> > > These two functions now have a very similar structure, and their first
> > > part (calling recvmmsg()) is functionally identical.  So, merge the two
> > > functions into one.
> > > 
> > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > > ---
> > >  udp.c | 86 +++++++++++++++++++----------------------------------------
> > >  1 file changed, 28 insertions(+), 58 deletions(-)
> > > 
> > > diff --git a/udp.c b/udp.c
> > > index 7c601cc..6ccfe8c 100644
> > > --- a/udp.c
> > > +++ b/udp.c
> > > @@ -590,52 +590,6 @@ static void udp_splice_sendfrom(const struct ctx *c, unsigned start, unsigned n,
> > >  	sendmmsg(s, mmh_send + start, n, MSG_NOSIGNAL);
> > >  }
> > >  
> > > -/**
> > > - * udp_sock_handler_splice() - Handler for socket mapped to "spliced" connection
> > > - * @c:		Execution context
> > > - * @ref:	epoll reference
> > > - * @events:	epoll events bitmap
> > > - * @now:	Current timestamp
> > > - */
> > > -static void udp_sock_handler_splice(const struct ctx *c, union epoll_ref ref,
> > > -				    uint32_t events, const struct timespec *now)
> > > -{
> > > -	in_port_t dst = ref.r.p.udp.udp.port;
> > > -	int v6 = ref.r.p.udp.udp.v6, n, i, m;
> > > -	struct mmsghdr *mmh_recv;
> > > -
> > > -	if (!(events & EPOLLIN))
> > > -		return;
> > > -
> > > -	if (v6)
> > > -		mmh_recv = udp6_l2_mh_sock;
> > > -	else
> > > -		mmh_recv = udp4_l2_mh_sock;
> > > -
> > > -	n = recvmmsg(ref.r.s, mmh_recv, UDP_MAX_FRAMES, 0, NULL);
> > > -
> > > -	if (n <= 0)
> > > -		return;
> > > -
> > > -	if (v6)
> > > -		udp_localname6.sin6_port = htons(dst);
> > > -	else
> > > -		udp_localname4.sin_port = htons(dst);
> > > -
> > > -	for (i = 0; i < n; i += m) {
> > > -		in_port_t src = sa_port(v6, mmh_recv[i].msg_hdr.msg_name);
> > > -
> > > -		for (m = 1; i + m < n; m++) {
> > > -			void *mname = mmh_recv[i + m].msg_hdr.msg_name;
> > > -			if (sa_port(v6, mname) != src)
> > > -				break;
> > > -		}
> > > -
> > > -		udp_splice_sendfrom(c, i, m, src, dst, v6, ref.r.p.udp.udp.ns,
> > > -				    ref.r.p.udp.udp.orig, now);
> > > -	}
> > > -}
> > > -
> > >  /**
> > >   * udp_update_hdr4() - Update headers for one IPv4 datagram
> > >   * @c:		Execution context
> > > @@ -945,27 +899,43 @@ void udp_sock_handler(const struct ctx *c, union epoll_ref ref, uint32_t events,
> > >  {
> > >  	in_port_t dstport = ref.r.p.udp.udp.port;
> > >  	bool v6 = ref.r.p.udp.udp.v6;
> > > -	struct mmsghdr *sock_mmh;
> > > +	struct mmsghdr *mmh_recv;
> > > +	unsigned int i, m;
> > >  	ssize_t n;
> > >  
> > > -	if (events == EPOLLERR)
> > > +	if (!(events & EPOLLIN))  
> > 
> > Pre-existing, unrelated issue, but this reminds me: we don't handle
> > socket errors here, and while udp_timer_one() will drop any sockets we
> > created, eventually, it would probably be better to act right away.  
> 
> Ok... I'm not sure what, if anything, you would like me to do about
> it, however.

No no, sorry, nothing, I wanted to share in case you happen to touch
this again soon, or if you had thoughts about it. I can fix this
separately once you're done with changes for UDP.

-- 
Stefano