From bd3ad7d3a14b07aeeb4f92abc757672719e2a0eb Mon Sep 17 00:00:00 2001 From: Sunil Goutham Date: Thu, 1 Dec 2016 18:24:28 +0530 Subject: net: thunderx: Fix transmit queue timeout issue Transmit queue timeout issue is seen in two cases - Due to a race condition btw setting stop_queue at xmit() and checking for stopped_queue in NAPI poll routine, at times transmission from a SQ comes to a halt. This is fixed by using barriers and also added a check for SQ free descriptors, incase SQ is stopped and there are only CQE_RX i.e no CQE_TX. - Contrary to an assumption, a HW errata where HW doesn't stop transmission even though there are not enough CQEs available for a CQE_TX is not fixed in T88 pass 2.x. This results in a Qset error with 'CQ_WR_FULL' stalling transmission. This is fixed by adjusting RXQ's RED levels for CQ level such that there is always enough space left for CQE_TXs. Signed-off-by: Sunil Goutham Signed-off-by: David S. Miller --- drivers/net/ethernet/cavium/thunder/nicvf_main.c | 52 ++++++++++++++++++++---- 1 file changed, 43 insertions(+), 9 deletions(-) (limited to 'drivers/net/ethernet/cavium/thunder/nicvf_main.c') diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_main.c b/drivers/net/ethernet/cavium/thunder/nicvf_main.c index 1eacec85dac3..2006f58b14b1 100644 --- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c +++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c @@ -644,6 +644,7 @@ static int nicvf_cq_intr_handler(struct net_device *netdev, u8 cq_idx, struct cmp_queue *cq = &qs->cq[cq_idx]; struct cqe_rx_t *cq_desc; struct netdev_queue *txq; + struct snd_queue *sq; unsigned int tx_pkts = 0, tx_bytes = 0; spin_lock_bh(&cq->lock); @@ -709,16 +710,20 @@ loop: done: /* Wakeup TXQ if its stopped earlier due to SQ full */ - if (tx_done) { + sq = &nic->qs->sq[cq_idx]; + if (tx_done || + (atomic_read(&sq->free_cnt) >= MIN_SQ_DESC_PER_PKT_XMIT)) { netdev = nic->pnicvf->netdev; txq = netdev_get_tx_queue(netdev, nicvf_netdev_qidx(nic, cq_idx)); if (tx_pkts) netdev_tx_completed_queue(txq, tx_pkts, tx_bytes); - nic = nic->pnicvf; + /* To read updated queue and carrier status */ + smp_mb(); if (netif_tx_queue_stopped(txq) && netif_carrier_ok(netdev)) { - netif_tx_start_queue(txq); + netif_tx_wake_queue(txq); + nic = nic->pnicvf; this_cpu_inc(nic->drv_stats->txq_wake); if (netif_msg_tx_err(nic)) netdev_warn(netdev, @@ -1054,6 +1059,9 @@ static netdev_tx_t nicvf_xmit(struct sk_buff *skb, struct net_device *netdev) struct nicvf *nic = netdev_priv(netdev); int qid = skb_get_queue_mapping(skb); struct netdev_queue *txq = netdev_get_tx_queue(netdev, qid); + struct nicvf *snic; + struct snd_queue *sq; + int tmp; /* Check for minimum packet length */ if (skb->len <= ETH_HLEN) { @@ -1061,13 +1069,39 @@ static netdev_tx_t nicvf_xmit(struct sk_buff *skb, struct net_device *netdev) return NETDEV_TX_OK; } - if (!netif_tx_queue_stopped(txq) && !nicvf_sq_append_skb(nic, skb)) { + snic = nic; + /* Get secondary Qset's SQ structure */ + if (qid >= MAX_SND_QUEUES_PER_QS) { + tmp = qid / MAX_SND_QUEUES_PER_QS; + snic = (struct nicvf *)nic->snicvf[tmp - 1]; + if (!snic) { + netdev_warn(nic->netdev, + "Secondary Qset#%d's ptr not initialized\n", + tmp - 1); + dev_kfree_skb(skb); + return NETDEV_TX_OK; + } + qid = qid % MAX_SND_QUEUES_PER_QS; + } + + sq = &snic->qs->sq[qid]; + if (!netif_tx_queue_stopped(txq) && + !nicvf_sq_append_skb(snic, sq, skb, qid)) { netif_tx_stop_queue(txq); - this_cpu_inc(nic->drv_stats->txq_stop); - if (netif_msg_tx_err(nic)) - netdev_warn(netdev, - "%s: Transmit ring full, stopping SQ%d\n", - netdev->name, qid); + + /* Barrier, so that stop_queue visible to other cpus */ + smp_mb(); + + /* Check again, incase another cpu freed descriptors */ + if (atomic_read(&sq->free_cnt) > MIN_SQ_DESC_PER_PKT_XMIT) { + netif_tx_wake_queue(txq); + } else { + this_cpu_inc(nic->drv_stats->txq_stop); + if (netif_msg_tx_err(nic)) + netdev_warn(netdev, + "%s: Transmit ring full, stopping SQ%d\n", + netdev->name, qid); + } return NETDEV_TX_BUSY; } -- cgit v1.2.3