Felix Fietkau <nbd@xxxxxxxx> writes:
> On 2016-07-06 18:16, Toke Høiland-Jørgensen wrote:
>> This switches ath9k over to using the mac80211 intermediate software
>> queueing mechanism for data packets. It removes the queueing inside the
>> driver, except for the retry queue, and instead pulls from mac80211 when
>> a packet is needed. The retry queue is used to store a packet that was
>> pulled but can't be sent immediately.
>>
>> The old code path in ath_tx_start that would queue packets has been
>> removed completely, as has the qlen limit tunables (since there's no
>> longer a queue in the driver to limit).
>>
>> Based on Tim's original patch set, but reworked quite thoroughly.
>>
>> Cc: Tim Shepard <shep@xxxxxxxxxxxx>
>> Cc: Felix Fietkau <nbd@xxxxxxxx>
>> Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxx>
>> ---
>> Changes since v1:
>> - Remove the old intermediate queueing logic completely instead of
>> just disabling it.
>> - Remove the qlen debug tunables.
>> - Remove the force_channel parameter from struct txctl (since we just
>> removed the code path that was using it).
>>
>> drivers/net/wireless/ath/ath9k/ath9k.h | 12 +-
>> drivers/net/wireless/ath/ath9k/channel.c | 2 -
>> drivers/net/wireless/ath/ath9k/debug.c | 14 +-
>> drivers/net/wireless/ath/ath9k/debug.h | 2 -
>> drivers/net/wireless/ath/ath9k/debug_sta.c | 4 +-
>> drivers/net/wireless/ath/ath9k/init.c | 2 +-
>> drivers/net/wireless/ath/ath9k/main.c | 1 +
>> drivers/net/wireless/ath/ath9k/xmit.c | 307 +++++++++++------------------
>> 8 files changed, 130 insertions(+), 214 deletions(-)
> Nice work!
Thanks :)
>> diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
>> index fe795fc..4077eeb 100644
>> --- a/drivers/net/wireless/ath/ath9k/xmit.c
>> +++ b/drivers/net/wireless/ath/ath9k/xmit.c
>> @@ -912,8 +923,16 @@ ath_tx_get_tid_subframe(struct ath_softc *sc, struct ath_txq *txq,
>> seqno = bf->bf_state.seqno;
>>
>> /* do not step over block-ack window */
>> - if (!BAW_WITHIN(tid->seq_start, tid->baw_size, seqno))
>> + if (!BAW_WITHIN(tid->seq_start, tid->baw_size, seqno)) {
>> + __skb_queue_tail(&tid->retry_q, skb);
>> +
>> + /* If there are other skbs in the retry q, they are
>> + * probably within the BAW, so loop immediately to get
>> + * one of them. Otherwise the queue can get stuck. */
>> + if (!skb_queue_is_first(&tid->retry_q, skb))
>> + continue;
> Not sure if this can happen, but if we ever somehow end up with two skbs
> in the retry queue that do not fit into the Block-Ack window, there's
> potential for an infinite loop here.
Yes, I realise that (v1 contained a comment on that). However, I don't
actually think it can happen: The code will only ever put one skb from
the intermediate queues on the retry queue (ath_tid_pull() is only
called if the retry queue is empty). Everything else on there are actual
retries that have been put on there by ath_tx_complete_aggr(). Figure
the latter will always be within the BAW?
-Toke
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