On Fri, Mar 22, 2019 at 04:44:09PM +0100, Arnd Bergmann wrote: > From: Eric Dumazet <edumazet@xxxxxxxxxx> > > Per listen(fd, backlog) rules, there is really no point accepting a SYN, > sending a SYNACK, and dropping the following ACK packet if accept queue > is full, because application is not draining accept queue fast enough. > > This behavior is fooling TCP clients that believe they established a > flow, while there is nothing at server side. They might then send about > 10 MSS (if using IW10) that will be dropped anyway while server is under > stress. > > Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> > Acked-by: Neal Cardwell <ncardwell@xxxxxxxxxx> > Acked-by: Yuchung Cheng <ycheng@xxxxxxxxxx> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> > (cherry picked from commit 5ea8ea2cb7f1d0db15762c9b0bb9e7330425a071) Also queued up for 4.9.y