On Fri, Dec 18, 2015 at 11:00 PM, Willy Tarreau <w...@1wt.eu> wrote: > On Fri, Dec 18, 2015 at 06:38:03PM -0800, Eric Dumazet wrote: >> On Fri, 2015-12-18 at 19:58 +0100, Willy Tarreau wrote: >> > Hi Josh, >> > >> > On Fri, Dec 18, 2015 at 08:33:45AM -0800, Josh Snyder wrote: >> > > I was also puzzled that binding succeeded. Looking into the code paths >> > > involved, in inet_csk_get_port, we quickly goto have_snum. From there, >> > > we end >> > > up dropping into tb_found. Since !hlist_empty(&tb->owners), we end up >> > > checking >> > > that (tb->fastreuseport > 0 && sk->sk_reuseport && uid_eq(tb->fastuid, >> > > uid)). >> > > This test passes, so we goto success and bind. >> > > >> > > Crucially, we are checking the fastreuseport field on the >> > > inet_bind_bucket, and >> > > not the sk_reuseport variable on the other sockets in the bucket. Since >> > > this >> > > bit is set based on sk_reuseport at the time the first socket binds (see >> > > tb_not_found), I can see no reason why sockets need to keep SO_REUSEPORT >> > > set >> > > beyond initial binding. >> > > >> > > Given this, I believe Willy's patch elegantly solves the problem at hand. >> > >> > Great, thanks for your in-depth explanation. >> > >> > Eric, do you think that this patch may be acceptable material for next >> > merge window (given that it's not a fix per-se) ? If so I'll resubmit >> > later. >> >> I need to check with Craig Gallek, because he was about to upstream a >> change to make SO_REUSEPORT more scalable & sexy (like having an [e]BPF >> filter to perform the selection in an array of sockets) > > OK fine. Please note that I also considered using a new value instead of > zero there but I preferred to avoid it since the man talked about zero/ > non-zero so I wanted to limit any API change. If Craig adds new values > there then this is something we can reconsider. > Is there any reason why this turning off a soreuseport socket should not apply to UDP also? (seems like we have a need to turn off RX but not TX for a UDP socket).
Tom > Have a nice week-end, > Willy > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
