Date: Sun, 27 Sep 2015 17:58:35 +0300 From: Alexander V. Chernikov <melifaro@freebsd.org> To: Bjoern A. Zeeb <bz@freebsd.org>, George Neville-Neil <gnn@freebsd.org> Cc: "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r288301 - in head/sys: net netinet netinet6 Message-ID: <2804821443365915@web20g.yandex.ru> In-Reply-To: <alpine.BSF.2.00.1509271225300.92377@ai.fobar.qr> References: <201509270529.t8R5TYRf095540@repo.freebsd.org> <alpine.BSF.2.00.1509271225300.92377@ai.fobar.qr>
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27.09.2015, 15:26, "Bjoern A. Zeeb" <bz@FreeBSD.org>: > On Sun, 27 Sep 2015, Alexander V. Chernikov wrote: > >> šAuthor: melifaro >> šDate: Sun Sep 27 05:29:34 2015 >> šNew Revision: 288301 >> šURL: https://svnweb.freebsd.org/changeset/base/288301 >> >> šLog: >> ššEliminate nd6_nud_hint() and its TCP bindings. >> >> ššInitially function was introduced in r53541 (KAME initial commit) to >> šššš"provide hints from upper layer protocols that indicate a connection >> ššššis making "forward progress"" (quote from RFC 2461 7.3.1 Reachability >> ššššConfirmation). >> ššHowever, it was converted to do nothing (e.g. just return) in r122922 >> šššš(tcp_hostcache implementation) back in 2003. Some defines were moved >> ššššto tcp_var.h in r169541. Then, it was broken (for non-corner cases) >> ššššby r186119 (L2<>L3 split) in 2008 (NULL ifp in nd6_lookup). So, >> ššššright now this code is broken and has no "real" base users. >> >> ššDifferential Revision: https://reviews.freebsd.org/D3699 > > PR: 165692 > > It would be nice to have the feature back though it would be very > expensive locking wise if it'd remain a per-packet operation. It looks like there are options to implement this without significant overhead (like, on proper TCP session teardown, or on delayed-ack timer, or/and with some sort of sampling + special "no-gw" flag). I'd prefer not to shift my focus from projects/routing now, but I can cooperate with someone from TCP side and resurrect/test nd6_nud_hint() > > -- > Bjoern A. Zeeb "Come on. Learn, goddamn it.", WarGames, 1983
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