Hi, > We encountered a problem that we use the extra_tx_headroom to reserve the headroom > which we put the txdesc in. > > Current workaround is that we check our needed headroom size by skb_headroom() > in the driver layer. > > Is extra_tx_headroom in struct ieee80211_hw always guaranteed? It _should_ be, IMHO. Having the check in all the drivers would be pointless. > The header file describes: > * @extra_tx_headroom: headroom to reserve in each transmit skb > * for use by the driver (e.g. for transmit headers.) > > But when the skb goes through the ieee80211_amsdu_realloc_pad(), it does not > take care of the extra_tx_headroom, i.e. the original reserved headroom might be > eaten. OK, so I guess that's a bug there. > Does the ieee80211_amsdu_realloc_pad() lacks some check for extra_tx_headroom > or the extra_tx_headroom in mac80211 is not guaranteed? I would say it lacks the checks - want to send a patch? > Furthermore, for the packet that would not be aggregate in A-MSDU and ndev->needed_headroom > is not guaranteed, in this case whether mac80211 layer still guarantee the extra_tx_headroom ? Yes, this case should be handled. johannes
