> The intent of the wording was probably written without considering
> Extended Key IDs. At least it makes no sense for me to forbid mixing
> MPDUs using keyid 0 and 1 in one A-MPDU.
I think it may make sense - reprogramming the hardware engines may take
some time, and doing that in the middle of the A-MPDU may not be
feasible? You don't just have to load the key (that you need to do
anyway) but also extract the status? I dunno, I'm more handwaving, but
it doesn't make sense to add such a requirement when only one key index
can be used to start with.
> The code is assuming that the driver is not aggregating MPDUs more than
> 5s apart. We probably don't have wait nearly so long but I'm not sure
> what is the minimum time.
OTOH, if you have a lot of BE/VI/VO traffic BK might be starved even
longer than that, technically indefinitely.
> +static struct ieee80211_key debug_noinline
> +*ieee80211_select_sta_key(struct ieee80211_tx_data *tx)
> +{
> + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
> + struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
> + struct sta_info *sta = tx->sta;
> + struct ieee80211_key *key;
> + struct ieee80211_key *next_key;
> +
> + key = rcu_dereference(tx->sta->ptk[tx->sta->ptk_idx]);
> +
> + if (likely(sta->ptk_idx_next == INVALID_PTK_KEYIDX))
> + return key;
> +
> + /* Only when using Extended Key ID the code below can be executed */
> +
> + if (!ieee80211_is_data_present(hdr->frame_control))
> + return key;
> +
> + if (sta->ptk_idx_next == sta->ptk_idx) {
> + /* First packet using new key with A-MPDU active*/
> + sta->ptk_idx_next = INVALID_PTK_KEYIDX;
> + ieee80211_check_fast_xmit(tx->sta);
I'm not convinced you can call this from this context? It looks safe
though, but it's really strange in a way.
> + info->flags &= ~IEEE80211_TX_CTL_AMPDU;
Like you say above, I don't think this really makes a lot of sense. If
we don't have any free bits I guess we should try to find some ...
johannes
