Date: Tue, 17 Mar 2009 08:12:58 +0000 From: Bruce Simpson <bms@incunabulum.net> To: Sam Leffler <sam@freebsd.org> Cc: current@freebsd.org, Coleman Kane <cokane@freebsd.org>, freebsd-net <net@freebsd.org> Subject: Re: IGMP+WiFi panic on recent kernel - in igmp_fasttimo() Message-ID: <49BF5B8A.4040108@incunabulum.net> In-Reply-To: <49BEB312.7060105@freebsd.org> References: <1236937253.2282.0.camel@localhost> <49BAEA9F.8020302@incunabulum.net> <49BB0D3E.2020306@incunabulum.net> <49BC1C66.7030400@freebsd.org> <1237233210.84180.20.camel@localhost> <49BEB312.7060105@freebsd.org>
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Sam Leffler wrote:
> It is the same issue but the root cause is unclear. There is much
> code that does assumes ifma_protospec might be NULL and checks for
> it. In my case (creating a wlan ifnet and then destroying it on
> eject) the patch below is sufficient. I don't care to dig right now
> to understand how this stuff is supposed to work; it should be clear
> from comments etc but the code is lacking.
>
This is just to say I've tried to reproduce the 802.11 related
panics, however have hit a brick wall because the PCI-CardBus bridge
does not seem to detect anything in its slot. (1U Itox Expanding Dragon
industrial PC w/a SiteCom branded Ricoh RL475 cardbus card). I tried
unloading if_fxp with IGMPv3 active on the ifnet, and didn't see any
panic, I'm assuming this is OK for the time being.
Qing Li volunteered to test IGMPv3 out for any VLAN related issues
-- I understand it stacks ifnets in a similar way to that of 802.11 --
however I have had no feedback from him since last week.
So I'm waiting for a HEAD build to a USB2 stick to finish, so I can
try testing nondestructively on my laptop, where I know for sure that
the PCI-CardBus bridge slot works, and I can detach an 802.11 card on
the fly.
Re ifma_protospec: Yes, there are tricks in the ifnet/in layer which
set it to NULL and look for it to be NULL. I ended up doing it this way
mainly because adding reference counting to ifnet would have simply been
too much work, and it's really a ball that needs to be kicked around at
a dev summit. However time presses on and it's better to get SOMETHING
out there.
Most likely the IGMPv3 changes are hitting this in the 802.11 case
somehow, I don't have a complete picture of how/why/what's going on, and
have been relying on feedback from others so far.
cheers
BMS
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