From 234132960dcf8ebd9d424d92a4dfb0e57fa63a17 Mon Sep 17 00:00:00 2001 From: Bruno Randolf Date: Fri, 17 Sep 2010 11:37:07 +0900 Subject: [PATCH] ath5k: Keep last descriptor in queue If we return a TX descriptor to the pool of available descriptors, while a queues TXDP still points to it we could potentially run into all sorts of troube. It has been suggested that there is hardware which can set the descriptors done bit before it reads ds_link and moves on to the next descriptor. While the documentation says this is not true for newer chipsets (the descriptor contents are copied to some internal memory), we don't know about older hardware. To be safe, we always keep the last descriptor in the queue, and avoid dangling TXDP pointers. Unfortunately this does not fully resolve the problem - queues still get stuck! This is similar to what ath9k does. Signed-off-by: Bruno Randolf Signed-off-by: John W. Linville --- drivers/net/wireless/ath/ath5k/base.c | 64 +++++++++++++-------------- 1 file changed, 32 insertions(+), 32 deletions(-) diff --git a/drivers/net/wireless/ath/ath5k/base.c b/drivers/net/wireless/ath/ath5k/base.c index cae9fe4676e..3e5ed6c0c80 100644 --- a/drivers/net/wireless/ath/ath5k/base.c +++ b/drivers/net/wireless/ath/ath5k/base.c @@ -1586,44 +1586,44 @@ ath5k_tx_processq(struct ath5k_softc *sc, struct ath5k_txq *txq) spin_lock(&txq->lock); list_for_each_entry_safe(bf, bf0, &txq->q, list) { - ds = bf->desc; + + txq->txq_poll_mark = false; + + /* skb might already have been processed last time. */ + if (bf->skb != NULL) { + ds = bf->desc; + + ret = sc->ah->ah_proc_tx_desc(sc->ah, ds, &ts); + if (unlikely(ret == -EINPROGRESS)) + break; + else if (unlikely(ret)) { + ATH5K_ERR(sc, + "error %d while processing " + "queue %u\n", ret, txq->qnum); + break; + } + + skb = bf->skb; + bf->skb = NULL; + pci_unmap_single(sc->pdev, bf->skbaddr, skb->len, + PCI_DMA_TODEVICE); + ath5k_tx_frame_completed(sc, skb, &ts); + } /* * It's possible that the hardware can say the buffer is * completed when it hasn't yet loaded the ds_link from - * host memory and moved on. If there are more TX - * descriptors in the queue, wait for TXDP to change - * before processing this one. + * host memory and moved on. + * Always keep the last descriptor to avoid HW races... */ - if (ath5k_hw_get_txdp(sc->ah, txq->qnum) == bf->daddr && - !list_is_last(&bf->list, &txq->q)) - break; - ret = sc->ah->ah_proc_tx_desc(sc->ah, ds, &ts); - if (unlikely(ret == -EINPROGRESS)) - break; - else if (unlikely(ret)) { - ATH5K_ERR(sc, "error %d while processing queue %u\n", - ret, txq->qnum); - break; + if (ath5k_hw_get_txdp(sc->ah, txq->qnum) != bf->daddr) { + spin_lock(&sc->txbuflock); + list_move_tail(&bf->list, &sc->txbuf); + sc->txbuf_len++; + txq->txq_len--; + spin_unlock(&sc->txbuflock); } - - skb = bf->skb; - bf->skb = NULL; - pci_unmap_single(sc->pdev, bf->skbaddr, skb->len, - PCI_DMA_TODEVICE); - - ath5k_tx_frame_completed(sc, skb, &ts); - - spin_lock(&sc->txbuflock); - list_move_tail(&bf->list, &sc->txbuf); - sc->txbuf_len++; - txq->txq_len--; - spin_unlock(&sc->txbuflock); - - txq->txq_poll_mark = false; } - if (likely(list_empty(&txq->q))) - txq->link = NULL; spin_unlock(&txq->lock); if (txq->txq_len < ATH5K_TXQ_LEN_LOW) ieee80211_wake_queue(sc->hw, txq->qnum); @@ -2188,7 +2188,7 @@ ath5k_tx_complete_poll_work(struct work_struct *work) if (sc->txqs[i].setup) { txq = &sc->txqs[i]; spin_lock_bh(&txq->lock); - if (txq->txq_len > 0) { + if (txq->txq_len > 1) { if (txq->txq_poll_mark) { ATH5K_DBG(sc, ATH5K_DEBUG_XMIT, "TX queue stuck %d\n", -- 2.20.1