Date: Tue, 17 Mar 2009 12:02:42 -0700 From: Sam Leffler <sam@freebsd.org> To: Bruce Simpson <bms@incunabulum.net> 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: <49BFF3D2.4030407@freebsd.org> In-Reply-To: <49BFA8A2.5080807@incunabulum.net> 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> <49BF5B8A.4040108@incunabulum.net> <1237295117.1844.6.camel@localhost> <49BFA8A2.5080807@incunabulum.net>
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Bruce Simpson wrote:
> Coleman Kane wrote:
>> If you are looking for a reliable test case, this might be it for you,
>> but I think you need a wlan interface to test it with:
>> * Install net/avahi from ports
>> * Set avahi_daemon_enable="YES" in rc.conf
>> * Configure VAP params for wlan0 card in rc.conf
>> * Log in and run "dhclient wlan0" to trigger the panic
>>
>>
>
> Actually I was able to panic the kernel right away with the 802.11
> code, just
> by joining a multicast group with mtest(8) on the wlan interface.
>
> i.e.
>
> # mtest
> j 224.0.0.2 192.168.x.x
> -> boom
>
> I believe I've found the symptom, but the root cause I don't fully
> understand.
> Sam indicated that the VAP code is using ifma's in some nested way
> between
> the ifnets which comprise the VAP's member interfaces.
>
> A workaround is pending....
>
net80211 uses the public api's to push mcast addresses from the vap's to
the parent ifnet. It does not directly frob any internal data
structures except to workaround the ioctl-based callback out of the
mcast code when adding an address. Look at ieee80211_ioctl_updatemulti
for details.
Sam
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