ath9k: rework tx queue selection and fix queue stopping/waking

The current ath9k tx queue handling code showed a few issues that could
lead to locking issues, tx stalls due to stopped queues, and maybe even
DMA issues.

The main source of these issues is that in some places the queue is
selected via skb queue mapping in places where this mapping may no
longer be valid. One such place is when data frames are transmitted via
the CAB queue (for powersave buffered frames). This is made even worse
by a lookup WMM AC values from the assigned tx queue (which is
undefined for the CAB queue).

This messed up the pending frame counting, which in turn caused issues
with queues getting stopped, but not woken again.

To fix these issues, this patch removes an unnecessary abstraction
separating a driver internal queue number from the skb queue number
(not to be confused with the hardware queue number).

It seems that this abstraction may have been necessary because of tx
queue preinitialization from the initvals. This patch avoids breakage
here by pushing the software <-> hardware queue mapping to the function
that assigns the tx queues and redefining the WMM AC definitions to
match the numbers used by mac80211 (also affects ath9k_htc).

To ensure consistency wrt. pending frame count tracking, these counters
are moved to the ath_txq struct, updated with the txq lock held, but
only where the tx queue selected by the skb queue map actually matches
the tx queue used by the driver for the frame.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Reported-by: Björn Smedman <bjorn.smedman@venatech.se>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 19 insertions, 17 deletions

diff --git a/drivers/net/wireless/ath/ath9k/debug.c b/drivers/net/wireless/ath/ath9k/debug.c
index a4052711eca8..0c3c74c157fb 100644
--- a/drivers/net/wireless/ath/ath9k/debug.c
+++ b/drivers/net/wireless/ath/ath9k/debug.c
@@ -585,10 +585,10 @@ static const struct file_operations fops_wiphy = {
 	do {								\
 		len += snprintf(buf + len, size - len,			\
 				"%s%13u%11u%10u%10u\n", str,		\
-		sc->debug.stats.txstats[sc->tx.hwq_map[WME_AC_BE]].elem, \
-		sc->debug.stats.txstats[sc->tx.hwq_map[WME_AC_BK]].elem, \
-		sc->debug.stats.txstats[sc->tx.hwq_map[WME_AC_VI]].elem, \
-		sc->debug.stats.txstats[sc->tx.hwq_map[WME_AC_VO]].elem); \
+		sc->debug.stats.txstats[WME_AC_BE].elem, \
+		sc->debug.stats.txstats[WME_AC_BK].elem, \
+		sc->debug.stats.txstats[WME_AC_VI].elem, \
+		sc->debug.stats.txstats[WME_AC_VO].elem); \
 } while(0)
 
 static ssize_t read_file_xmit(struct file *file, char __user *user_buf,
@@ -630,33 +630,35 @@ static ssize_t read_file_xmit(struct file *file, char __user *user_buf,
 	return retval;
 }
 
-void ath_debug_stat_tx(struct ath_softc *sc, struct ath_txq *txq,
-		       struct ath_buf *bf, struct ath_tx_status *ts)
+void ath_debug_stat_tx(struct ath_softc *sc, struct ath_buf *bf,
+		       struct ath_tx_status *ts)
 {
-	TX_STAT_INC(txq->axq_qnum, tx_pkts_all);
-	sc->debug.stats.txstats[txq->axq_qnum].tx_bytes_all += bf->bf_mpdu->len;
+	int qnum = skb_get_queue_mapping(bf->bf_mpdu);
+
+	TX_STAT_INC(qnum, tx_pkts_all);
+	sc->debug.stats.txstats[qnum].tx_bytes_all += bf->bf_mpdu->len;
 
 	if (bf_isampdu(bf)) {
 		if (bf_isxretried(bf))
-			TX_STAT_INC(txq->axq_qnum, a_xretries);
+			TX_STAT_INC(qnum, a_xretries);
 		else
-			TX_STAT_INC(txq->axq_qnum, a_completed);
+			TX_STAT_INC(qnum, a_completed);
 	} else {
-		TX_STAT_INC(txq->axq_qnum, completed);
+		TX_STAT_INC(qnum, completed);
 	}
 
 	if (ts->ts_status & ATH9K_TXERR_FIFO)
-		TX_STAT_INC(txq->axq_qnum, fifo_underrun);
+		TX_STAT_INC(qnum, fifo_underrun);
 	if (ts->ts_status & ATH9K_TXERR_XTXOP)
-		TX_STAT_INC(txq->axq_qnum, xtxop);
+		TX_STAT_INC(qnum, xtxop);
 	if (ts->ts_status & ATH9K_TXERR_TIMER_EXPIRED)
-		TX_STAT_INC(txq->axq_qnum, timer_exp);
+		TX_STAT_INC(qnum, timer_exp);
 	if (ts->ts_flags & ATH9K_TX_DESC_CFG_ERR)
-		TX_STAT_INC(txq->axq_qnum, desc_cfg_err);
+		TX_STAT_INC(qnum, desc_cfg_err);
 	if (ts->ts_flags & ATH9K_TX_DATA_UNDERRUN)
-		TX_STAT_INC(txq->axq_qnum, data_underrun);
+		TX_STAT_INC(qnum, data_underrun);
 	if (ts->ts_flags & ATH9K_TX_DELIM_UNDERRUN)
-		TX_STAT_INC(txq->axq_qnum, delim_underrun);
+		TX_STAT_INC(qnum, delim_underrun);
 }
 
 static const struct file_operations fops_xmit = {