Re: [PATCH] ath9k: Restart xmit logic in xmit watchdog.

[Ben Greear <greearb@candelatech.com>]

On 01/09/2011 10:19 AM, Felix Fietkau wrote:
> On 2011-01-09 12:46 AM, greearb@candelatech.com wrote:
>> From: Ben Greear<greearb@candelatech.com>
>>
>> The system can get into a state where the xmit queue
>> is stopped, but there are no packets pending, so
>> the queue will not be restarted.
>>
>> Add logic to the xmit watchdog to attempt to restart
>> the xmit logic if this situation is detected.
>>
>> Signed-off-by: Ben Greear<greearb@candelatech.com>
>> ---
>>
>> NOTE: This is basically the same as a patch I posted
>> a day or two ago. It doesn't address the concern of the
>> reviewer who NACK'd it, but my system will not properly
>> transmit packets without this patch applied. I realize
>> this is a bit of a hack, but until we find and fix all
>> of the other bugs, I think this patch or something similar
>> should be applied.
>>
>> Still, this patch should not be applied unless given positive
>> ACK by the ath9k developers.
>>
>> diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
>> index d9a4144..1b3a62c 100644
>> --- a/drivers/net/wireless/ath/ath9k/xmit.c
>> +++ b/drivers/net/wireless/ath/ath9k/xmit.c
>> @@ -1988,19 +1988,30 @@ static void ath_tx_rc_status(struct ath_buf *bf, struct ath_tx_status *ts,
>> tx_info->status.rates[tx_rateindex].count = ts->ts_longretry + 1;
>> }
>>
>> -static void ath_wake_mac80211_queue(struct ath_softc *sc, int qnum)
>> +/* Has no locking. */
>> +static void __ath_wake_mac80211_queue(struct ath_softc *sc, struct ath_txq *txq)
>> {
>> - struct ath_txq *txq;
>> -
>> - txq = sc->tx.txq_map[qnum];
>> - spin_lock_bh(&txq->axq_lock);
>> if (txq->stopped&& txq->pending_frames< ATH_MAX_QDEPTH) {
>> - if (ath_mac80211_start_queue(sc, qnum))
>> + if (ath_mac80211_start_queue(sc, txq->axq_qnum))
>> txq->stopped = 0;
>> }
>> +}
> This part is quite broken, I think you got confused with various types of queue numbers. txq->axq_qnum refers to the atheros hw queue index, whereas the qnum
> argument to this function refers to the mac80211 queue index (which is also the correct index for sc->tx.txq_map - not to be confused with the sc->tx.txq array).

Yeah, I am confused on all of this.  Looks like I should add a member to the txq struct to
record it's mac80211 index and use that instead?

In the upstream code, is this correct?  It seems to me that it should always
be waking 'txq' since it just completed a packet.  Why the check
against txq_map?

		if (txq == sc->tx.txq_map[qnum])
			ath_wake_mac80211_queue(sc, qnum);

> Pushing the locking out to the caller side (with a wrapper) does sound like a good idea though.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com