patches for if_iwi and wlan for WEP mode

Adrian Chadd adrian at freebsd.org
Thu Mar 8 19:38:10 UTC 2012


On 8 March 2012 07:43, John Baldwin <jhb at freebsd.org> wrote:

> However, you could do that by having a net80211_ifattach() type thing that
> sets if_transmit and invokes the driver-provided if_start.  I don't think
> wireless devices are using multiple transmit queues in such a way that
> if_transmit would be a benefit, and if_start is a simpler model.

THe problem is that the default if_transmit uses IFQ_ENQUEUE and the
_start() versions out there use IFQ_DEQUEUE without necessarily
handling fragments at all.

We end up having m->m_nextpkt NULL'ed upon IFQ_ENQUEUE, thus not only
making a fragment list entirely broken, the fragments themselves are
actually leaked. So we end up running out of mbufs.

The solution I can see working at the moment is creating if_transmit
for each wireless device and correctly handling any fragments in the
head mbuf before calling IFQ_DEQUEUE.


Adrian


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