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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