Date: Mon, 4 Dec 2006 22:57:04 +0100 From: Max Laier <max@love2party.net> To: freebsd-current@freebsd.org Cc: Munehiro Matsuda <haro@h4.dion.ne.jp>, rwatson@freebsd.org, bzeeb-lists@lists.zabbadoz.net Subject: Re: LOR with netisr changes Message-ID: <200612042257.12597.max@love2party.net> In-Reply-To: <200612041149.21533.jhb@freebsd.org> References: <20061128180811.P95096@fledge.watson.org> <20061204.004950.74755916.haro@h4.dion.ne.jp> <200612041149.21533.jhb@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
--nextPart2099711.ZZajPHy2dM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Monday 04 December 2006 17:49, John Baldwin wrote: > On Sunday 03 December 2006 10:49, Munehiro Matsuda wrote: > > From: John Baldwin <jhb-at-freebsd.org> > > Date: Wed, 29 Nov 2006 12:39:56 -0500 > > > > ::On Tuesday 28 November 2006 14:41, Sam Leffler wrote: > > ::> Robert Watson wrote: > > ::> > On Wed, 29 Nov 2006, Munehiro Matsuda wrote: > > ::> >> JFYI, I got following LOR started after the netisr changes: > > ::> > > > ::> > In general, device driver locks should not be held over entry > > ::> > to the network stack. However, things get a bit tricky in the > > ::> > 802.11 code due to lock sharing, I believe, so it could be a > > ::> > bit more tricky to fix that. > > ::> > > ::> It's just a bug in the driver. Driver locks should be dropped > > ::> when packets get passed up the stack. This issue was pointed out > > ::> before iwi ever was committed but since nothing immediately comes > > ::> back via the bridge (or similar) it's been ignored. > > :: > > ::How about this: > > > > <snip> > > > > ::(I'm unsure if the net82011 layer protects 'ic' or if the driver is > > :: supposed to do that.) That's the main problem of net80211 as far as I understand it. The 'ic'=20 stores a lot of state and configuration and it is unclear how it is=20 protected. Most of the time, it seems to be the driver's job. However,=20 there are entry points in net80211 that change the 'ic' underneath the=20 driver without giving them a chance to protect it. IIRC, there has been=20 the idea to expose a driver mutex to the net80211 layer in order to take=20 care of this - not sure what has become of that idea, though. > > Sorry for the late reply, and thanks for the patch. > > I needed to tweak the patch to make it compile, but seems to work > > fine. Modified patch attached. > > > > From: "Bjoern A. Zeeb" <bzeeb-lists-at-lists.zabbadoz.net> > > Date: Sat, 2 Dec 2006 12:25:28 +0000 (UTC) > > > > ::ok, whoever is going to take care of this and perhaps commit the > > :: fix let me know. I assigned it LOR ID 194 on "The LOR page": > > :: http://sources.zabbadoz.net/freebsd/lor.html#194 > > > > LOR seems to be gone with the patch, so it could be removed when > > committed. > > > > Thanks, > > Haro > > > > --- if_iwi.c.org 9 Nov 2006 16:05:43 -0000 > > +++ if_iwi.c 3 Dec 2006 14:17:45 -0000 > > @@ -1230,6 +1230,7 @@ > > struct mbuf *mnew, *m; > > struct ieee80211_node *ni; > > int type, error, framelen; > > + IWI_LOCK_DECL; > > Hmm, why this? If it's for spl's, note that the rest of the patch is > specific to 5.x and up, shouldn't really be dropping spl in 4.x. Also, > even if it did, it would pass a garbage value to splx(), so it would > really break things badly. No, this is a hack to work around a recursion in net80211. There are a=20 couple of places where the driver calls back into net80211 with the lock=20 held (to protect the 'ic', see above). net80211 then might call back=20 into the driver, which means we would have either have to use a recursive=20 lock (which can't be passed to msleep) or avoid the recursion at leat for=20 the lock (which is what IWI_LOCK_DECL does). I know it's ugly and wrong,=20 but unless there is a propper sollution as to how the net80211 data=20 structures are protected in various call paths, it's not something that=20 can be fixed. > > framelen =3D le16toh(frame->len); > > if (framelen < IEEE80211_MIN_LEN || framelen > MCLBYTES) { > > @@ -1310,6 +1311,7 @@ > > > > bpf_mtap2(sc->sc_drvbpf, tap, sc->sc_rxtap_len, m); > > } > > + IWI_UNLOCK(sc); > > > > ni =3D ieee80211_find_rxnode(ic, mtod(m, struct ieee80211_frame_min > > *)); > > > > @@ -1319,6 +1321,7 @@ > > /* node is no longer needed */ > > ieee80211_free_node(ni); > > > > + IWI_LOCK(sc); > > if (sc->sc_softled) { > > /* > > * Blink for any data frame. Otherwise do a > > > > =3D-------------------------------------------------------------------- > >---------- _ _ Munehiro (haro) Matsuda > > -|- /_\ |_|_| Internet Solution Dept., KGT Inc. > > /|\ |_| |_|_| 2-8-8 Shinjuku Shinjuku-ku Tokyo 160-0022, Japan > > Tel: +81-3-3225-0767 Fax: +81-3-3225-0740 =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 --nextPart2099711.ZZajPHy2dM Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (FreeBSD) iD8DBQBFdJm4XyyEoT62BG0RAqPQAJ42c99B19FWwsJy1Z86gOehNMk1swCfU1EV NwMI/uK2b53NZbhuLi6Q4Rc= =VQlv -----END PGP SIGNATURE----- --nextPart2099711.ZZajPHy2dM--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200612042257.12597.max>