> Whenever you run a monitor interface in mac80211, you can see lots of > truesize bugs: > > SKB BUG: Invalid truesize (464) len=307, sizeof(sk_buff)=176 > > It appears to be caused by mac80211's re-injection of the transmitted > frame. Regardless of the fact that I'm pretty sure that we have bugs with respect to pskb_expand_head in mac80211 that for some reason never show up unless you add monitors, this re-injection of frames is quite a hack. For one, it means that on a monitor interface you see every outgoing frame, even if it wasn't sent on that interface. That's actually quite nice, especially for debugging, but I think we can already see all transmitted packets on the master interface. Secondly, it means that actually injected packets show up twice, first via dev_queue_xmit_nit and then via the status reporting. Also, if we ever want to move towards an API where the driver need not give a TX status report for every frame (some hardware cannot do this) then this is at best a hack since we do not know the exact status for a frame. On the other hand, hostapd requires knowing whether a specific frame was acknowledged. Does anyone have any ideas how to implement such a status query for a frame that was sent? What hostapd does is open a raw socket and simply send a frame, but it needs to know whether that frame was acknowledged so currently it also listens on a monitor and checks all outgoing frames, which is suboptimal anyway. The only thing I could so far think of is like the socket timestamps but that seems rather bad to do for such a special case. johannes
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