IPoIB/cm: Use common CQ for CM send completions

Use the same CQ for CM send completions as for all other IPoIB
completions.  This means all completions are processed via the same
NAPI polling routine.  This should help reduce the number of
interrupts for bi-directional traffic (such as TCP) and fixes "driver
is hogging interrupts" errors reported for IPoIB send side, e.g.
<https://bugs.openfabrics.org/show_bug.cgi?id=508>

To do this, keep a per-interface counter of outstanding send WRs, and
stop the interface when this counter reaches the send queue size to
avoid CQ overruns.

Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 45 insertions, 67 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
index ddf0c54493c..87610772a97 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
@@ -87,7 +87,7 @@ static int ipoib_cm_post_receive(struct net_device *dev, int id)
 	struct ib_recv_wr *bad_wr;
 	int i, ret;
 
-	priv->cm.rx_wr.wr_id = id | IPOIB_CM_OP_SRQ;
+	priv->cm.rx_wr.wr_id = id | IPOIB_OP_CM | IPOIB_OP_RECV;
 
 	for (i = 0; i < IPOIB_CM_RX_SG; ++i)
 		priv->cm.rx_sge[i].addr = priv->cm.srq_ring[id].mapping[i];
@@ -401,7 +401,7 @@ static void skb_put_frags(struct sk_buff *skb, unsigned int hdr_space,
 void ipoib_cm_handle_rx_wc(struct net_device *dev, struct ib_wc *wc)
 {
 	struct ipoib_dev_priv *priv = netdev_priv(dev);
-	unsigned int wr_id = wc->wr_id & ~IPOIB_CM_OP_SRQ;
+	unsigned int wr_id = wc->wr_id & ~(IPOIB_OP_CM | IPOIB_OP_RECV);
 	struct sk_buff *skb, *newskb;
 	struct ipoib_cm_rx *p;
 	unsigned long flags;
@@ -412,7 +412,7 @@ void ipoib_cm_handle_rx_wc(struct net_device *dev, struct ib_wc *wc)
 		       wr_id, wc->status);
 
 	if (unlikely(wr_id >= ipoib_recvq_size)) {
-		if (wr_id == (IPOIB_CM_RX_DRAIN_WRID & ~IPOIB_CM_OP_SRQ)) {
+		if (wr_id == (IPOIB_CM_RX_DRAIN_WRID & ~(IPOIB_OP_CM | IPOIB_OP_RECV))) {
 			spin_lock_irqsave(&priv->lock, flags);
 			list_splice_init(&priv->cm.rx_drain_list, &priv->cm.rx_reap_list);
 			ipoib_cm_start_rx_drain(priv);
@@ -498,7 +498,7 @@ static inline int post_send(struct ipoib_dev_priv *priv,
 	priv->tx_sge.addr             = addr;
 	priv->tx_sge.length           = len;
 
-	priv->tx_wr.wr_id 	      = wr_id;
+	priv->tx_wr.wr_id 	      = wr_id | IPOIB_OP_CM;
 
 	return ib_post_send(tx->qp, &priv->tx_wr, &bad_wr);
 }
@@ -549,20 +549,19 @@ void ipoib_cm_send(struct net_device *dev, struct sk_buff *skb, struct ipoib_cm_
 		dev->trans_start = jiffies;
 		++tx->tx_head;
 
-		if (tx->tx_head - tx->tx_tail == ipoib_sendq_size) {
+		if (++priv->tx_outstanding == ipoib_sendq_size) {
 			ipoib_dbg(priv, "TX ring 0x%x full, stopping kernel net queue\n",
 				  tx->qp->qp_num);
 			netif_stop_queue(dev);
-			set_bit(IPOIB_FLAG_NETIF_STOPPED, &tx->flags);
 		}
 	}
 }
 
-static void ipoib_cm_handle_tx_wc(struct net_device *dev, struct ipoib_cm_tx *tx,
-				  struct ib_wc *wc)
+void ipoib_cm_handle_tx_wc(struct net_device *dev, struct ib_wc *wc)
 {
 	struct ipoib_dev_priv *priv = netdev_priv(dev);
-	unsigned int wr_id = wc->wr_id;
+	struct ipoib_cm_tx *tx = wc->qp->qp_context;
+	unsigned int wr_id = wc->wr_id & ~IPOIB_OP_CM;
 	struct ipoib_tx_buf *tx_req;
 	unsigned long flags;
 
@@ -587,11 +586,10 @@ static void ipoib_cm_handle_tx_wc(struct net_device *dev, struct ipoib_cm_tx *tx
 
 	spin_lock_irqsave(&priv->tx_lock, flags);
 	++tx->tx_tail;
-	if (unlikely(test_bit(IPOIB_FLAG_NETIF_STOPPED, &tx->flags)) &&
-	    tx->tx_head - tx->tx_tail <= ipoib_sendq_size >> 1) {
-		clear_bit(IPOIB_FLAG_NETIF_STOPPED, &tx->flags);
+	if (unlikely(--priv->tx_outstanding == ipoib_sendq_size >> 1) &&
+	    netif_queue_stopped(dev) &&
+	    test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
 		netif_wake_queue(dev);
-	}
 
 	if (wc->status != IB_WC_SUCCESS &&
 	    wc->status != IB_WC_WR_FLUSH_ERR) {
@@ -614,11 +612,6 @@ static void ipoib_cm_handle_tx_wc(struct net_device *dev, struct ipoib_cm_tx *tx
 			tx->neigh = NULL;
 		}
 
-		/* queue would be re-started anyway when TX is destroyed,
-		 * but it makes sense to do it ASAP here. */
-		if (test_and_clear_bit(IPOIB_FLAG_NETIF_STOPPED, &tx->flags))
-			netif_wake_queue(dev);
-
 		if (test_and_clear_bit(IPOIB_FLAG_INITIALIZED, &tx->flags)) {
 			list_move(&tx->list, &priv->cm.reap_list);
 			queue_work(ipoib_workqueue, &priv->cm.reap_task);
@@ -632,19 +625,6 @@ static void ipoib_cm_handle_tx_wc(struct net_device *dev, struct ipoib_cm_tx *tx
 	spin_unlock_irqrestore(&priv->tx_lock, flags);
 }
 
-static void ipoib_cm_tx_completion(struct ib_cq *cq, void *tx_ptr)
-{
-	struct ipoib_cm_tx *tx = tx_ptr;
-	int n, i;
-
-	ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
-	do {
-		n = ib_poll_cq(cq, IPOIB_NUM_WC, tx->ibwc);
-		for (i = 0; i < n; ++i)
-			ipoib_cm_handle_tx_wc(tx->dev, tx, tx->ibwc + i);
-	} while (n == IPOIB_NUM_WC);
-}
-
 int ipoib_cm_dev_open(struct net_device *dev)
 {
 	struct ipoib_dev_priv *priv = netdev_priv(dev);
@@ -807,17 +787,18 @@ static int ipoib_cm_rep_handler(struct ib_cm_id *cm_id, struct ib_cm_event *even
 	return 0;
 }
 
-static struct ib_qp *ipoib_cm_create_tx_qp(struct net_device *dev, struct ib_cq *cq)
+static struct ib_qp *ipoib_cm_create_tx_qp(struct net_device *dev, struct ipoib_cm_tx *tx)
 {
 	struct ipoib_dev_priv *priv = netdev_priv(dev);
 	struct ib_qp_init_attr attr = {
-		.send_cq		= cq,
+		.send_cq		= priv->cq,
 		.recv_cq		= priv->cq,
 		.srq			= priv->cm.srq,
 		.cap.max_send_wr	= ipoib_sendq_size,
 		.cap.max_send_sge	= 1,
 		.sq_sig_type		= IB_SIGNAL_ALL_WR,
 		.qp_type		= IB_QPT_RC,
+		.qp_context		= tx
         };
 
 	return ib_create_qp(priv->pd, &attr);
@@ -899,21 +880,7 @@ static int ipoib_cm_tx_init(struct ipoib_cm_tx *p, u32 qpn,
 		goto err_tx;
 	}
 
-	p->cq = ib_create_cq(priv->ca, ipoib_cm_tx_completion, NULL, p,
-			     ipoib_sendq_size + 1, 0);
-	if (IS_ERR(p->cq)) {
-		ret = PTR_ERR(p->cq);
-		ipoib_warn(priv, "failed to allocate tx cq: %d\n", ret);
-		goto err_cq;
-	}
-
-	ret = ib_req_notify_cq(p->cq, IB_CQ_NEXT_COMP);
-	if (ret) {
-		ipoib_warn(priv, "failed to request completion notification: %d\n", ret);
-		goto err_req_notify;
-	}
-
-	p->qp = ipoib_cm_create_tx_qp(p->dev, p->cq);
+	p->qp = ipoib_cm_create_tx_qp(p->dev, p);
 	if (IS_ERR(p->qp)) {
 		ret = PTR_ERR(p->qp);
 		ipoib_warn(priv, "failed to allocate tx qp: %d\n", ret);
@@ -950,12 +917,8 @@ err_modify:
 err_id:
 	p->id = NULL;
 	ib_destroy_qp(p->qp);
-err_req_notify:
 err_qp:
 	p->qp = NULL;
-	ib_destroy_cq(p->cq);
-err_cq:
-	p->cq = NULL;
 err_tx:
 	return ret;
 }
@@ -964,6 +927,8 @@ static void ipoib_cm_tx_destroy(struct ipoib_cm_tx *p)
 {
 	struct ipoib_dev_priv *priv = netdev_priv(p->dev);
 	struct ipoib_tx_buf *tx_req;
+	unsigned long flags;
+	unsigned long begin;
 
 	ipoib_dbg(priv, "Destroy active connection 0x%x head 0x%x tail 0x%x\n",
 		  p->qp ? p->qp->qp_num : 0, p->tx_head, p->tx_tail);
@@ -971,27 +936,40 @@ static void ipoib_cm_tx_destroy(struct ipoib_cm_tx *p)
 	if (p->id)
 		ib_destroy_cm_id(p->id);
 
-	if (p->qp)
-		ib_destroy_qp(p->qp);
-
-	if (p->cq)
-		ib_destroy_cq(p->cq);
-
-	if (test_bit(IPOIB_FLAG_NETIF_STOPPED, &p->flags))
-		netif_wake_queue(p->dev);
-
 	if (p->tx_ring) {
+		/* Wait for all sends to complete */
+		begin = jiffies;
 		while ((int) p->tx_tail - (int) p->tx_head < 0) {
-			tx_req = &p->tx_ring[p->tx_tail & (ipoib_sendq_size - 1)];
-			ib_dma_unmap_single(priv->ca, tx_req->mapping, tx_req->skb->len,
-					 DMA_TO_DEVICE);
-			dev_kfree_skb_any(tx_req->skb);
-			++p->tx_tail;
+			if (time_after(jiffies, begin + 5 * HZ)) {
+				ipoib_warn(priv, "timing out; %d sends not completed\n",
+					   p->tx_head - p->tx_tail);
+				goto timeout;
+			}
+
+			msleep(1);
 		}
+	}
 
-		kfree(p->tx_ring);
+timeout:
+
+	while ((int) p->tx_tail - (int) p->tx_head < 0) {
+		tx_req = &p->tx_ring[p->tx_tail & (ipoib_sendq_size - 1)];
+		ib_dma_unmap_single(priv->ca, tx_req->mapping, tx_req->skb->len,
+				    DMA_TO_DEVICE);
+		dev_kfree_skb_any(tx_req->skb);
+		++p->tx_tail;
+		spin_lock_irqsave(&priv->tx_lock, flags);
+		if (unlikely(--priv->tx_outstanding == ipoib_sendq_size >> 1) &&
+		    netif_queue_stopped(p->dev) &&
+		    test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
+			netif_wake_queue(p->dev);
+		spin_unlock_irqrestore(&priv->tx_lock, flags);
 	}
 
+	if (p->qp)
+		ib_destroy_qp(p->qp);
+
+	kfree(p->tx_ring);
 	kfree(p);
 }