Date: Wed, 21 Jun 2006 11:13:22 +0200 From: Max Laier <max@love2party.net> To: Maxim Konovalov <maxim@macomnet.ru> Cc: cvs-src@freebsd.org, Gleb Smirnoff <glebius@freebsd.org>, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/net if.c Message-ID: <200606211113.31621.max@love2party.net> In-Reply-To: <20060621120212.D93005@mp2.macomnet.net> References: <200606210602.k5L62Zor029243@repoman.freebsd.org> <20060621120212.D93005@mp2.macomnet.net>
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--nextPart2667997.84cDmJOyTc Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Wednesday 21 June 2006 10:06, Maxim Konovalov wrote: > On Wed, 21 Jun 2006, 06:02-0000, Gleb Smirnoff wrote: > > glebius 2006-06-21 06:02:35 UTC > > > > FreeBSD src repository > > > > Modified files: > > sys/net if.c > > Log: > > - First initialize ifnet, and then insert it into global > > list. > > - First remove from global list, then start destroying. > > > > PR: kern/97679 > > Submitted by: Alex Lyashkov <shadow itt.net.ru> > > Reviewed by: rwatson, brooks > > FWIW, even with Yar's recent commit to if_vlan.c it still panics. I > told Alex about that. A testcase below. Run it for several minutes. > > #11 0xc05e1a4a in calltrap () at /usr/src/sys/i386/i386/exception.s:138 > #12 0xc05608cb in in6ifa_ifpwithaddr (ifp=3D0xdeadc0de, addr=3D0xc39b5218) > at /usr/src/sys/netinet6/in6.c:1862 > #13 0xc055e81d in in6_control (so=3D0xc2bbda60, cmd=3D0xc1206949, > data=3D0xc39b5200 "vlan2349", ifp=3D0xc3973000, > td=3D0xc39b5210) at /usr/src/sys/netinet6/in6.c:459 > #14 0xc052c43c in ifioctl (so=3D0xc2bbda60, cmd=3D0xc1206949, > data=3D0xc39b5200 "vlan2349", td=3D0xc2afd870) > at /usr/src/sys/net/if.c:1530 > #15 0xc04efb47 in soo_ioctl (fp=3D0xdeadc0de, cmd=3D0xc1206949, > data=3D0xc39b5200, active_cred=3D0xc2e64700, td=3D0xc2afd870) > at /usr/src/sys/kern/sys_socket.c:214 > #16 0xc04ea810 in ioctl (td=3D0xc2afd870, uap=3D0xd56a7d04) at file.h:265 Yes, we simply keep too many implicit references to ifnets. The real seque= nce=20 for interface destruction should be: =46irst mark unusable, wait long enough[*], remove from global list***s***,= wait=20 long enough[*], free. Note that there is more than one global list an ifnet takes part in. There= is=20 the index2ifp table, there are address lists in inet[6] etc. etc. ... I tri= ed=20 to tackle this once and figured it was a minefield. It is one of the=20 problematic cases where we have *way* more reads than writes(=3Dchanges) an= d=20 nobody cared to introduce locking as we usually don't see the race effects. [*] Unfortunately we don't know what long enough is as we don't do referenc= e=20 counting for ifnets (and we shouldn't as it would be a massive performance= =20 hit). Waiting for as long a possible or at least for "a very long time"=20 would be a good start though. =2D-=20 /"\ Best regards, | mlaier@freebsd.org \ / Max Laier | ICQ #67774661 X http://pf4freebsd.love2party.net/ | mlaier@EFnet / \ ASCII Ribbon Campaign | Against HTML Mail and News --nextPart2667997.84cDmJOyTc Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (FreeBSD) iD8DBQBEmQ27XyyEoT62BG0RAuSNAJ9T860ecON1YzMxUq0Onqr3WiNSngCePihj u0tmDHLStwNGYK9jZ6MBk28= =Gpfz -----END PGP SIGNATURE----- --nextPart2667997.84cDmJOyTc--
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