Commit 82172b76 authored by Mike Marciniszyn's avatar Mike Marciniszyn Committed by Jason Gunthorpe
Browse files

IB/hfi1: Correct -EBUSY handling in tx code 

The current code mishandles -EBUSY in two ways:
- The flow change doesn't test the return from the flush and runs on to
  process the current packet racing with the wakeup processing
- The -EBUSY handling for a single packet inserts the tx into the txlist
  after the submit call, racing with the same wakeup processing

Fix the first by dropping the skb and returning NETDEV_TX_OK.

Fix the second by insuring the the list entry within the txreq is inited
when allocated.  This enables the sleep routine to detect that the txreq
has used the non-list api and queue the packet to the txlist.

Both flaws can lead to having the flushing thread executing in causing two
threads to manipulate the txlist.

Fixes: d99dc602 ("IB/hfi1: Add functions to transmit datagram ipoib packets")
Link: https://lore.kernel.org/r/20200623204321.108092.83898.stgit@awfm-01.aw.intel.com


Reviewed-by: default avatarKaike Wan <kaike.wan@intel.com>
Signed-off-by: default avatarMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: default avatarDennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent 822fbd37

drivers/infiniband/hw/hfi1/ipoib_tx.c

+18 −17
Original line number Diff line number Diff line
@@ -369,6 +369,7 @@ static struct ipoib_txreq *hfi1_ipoib_send_dma_common(struct net_device *dev, 
	tx->priv = priv;

	tx->txq = txp->txq;

	tx->skb = skb;

	INIT_LIST_HEAD(&tx->txreq.list);



	hfi1_ipoib_build_ib_tx_headers(tx, txp);
@@ -469,6 +470,7 @@ static int hfi1_ipoib_send_dma_single(struct net_device *dev, 


	ret = hfi1_ipoib_submit_tx(txq, tx);

	if (likely(!ret)) {

tx_ok:

		trace_sdma_output_ibhdr(tx->priv->dd,

					&tx->sdma_hdr.hdr,

					ib_is_sc5(txp->flow.sc5));
@@ -478,20 +480,8 @@ static int hfi1_ipoib_send_dma_single(struct net_device *dev, 


	txq->pkts_sent = false;



	if (ret == -EBUSY) {

		list_add_tail(&tx->txreq.list, &txq->tx_list);



		trace_sdma_output_ibhdr(tx->priv->dd,

					&tx->sdma_hdr.hdr,

					ib_is_sc5(txp->flow.sc5));

		hfi1_ipoib_check_queue_depth(txq);

		return NETDEV_TX_OK;

	}



	if (ret == -ECOMM) {

		hfi1_ipoib_check_queue_depth(txq);

		return NETDEV_TX_OK;

	}

	if (ret == -EBUSY || ret == -ECOMM)

		goto tx_ok;



	sdma_txclean(priv->dd, &tx->txreq);

	dev_kfree_skb_any(skb);
@@ -509,9 +499,17 @@ static int hfi1_ipoib_send_dma_list(struct net_device *dev, 
	struct ipoib_txreq *tx;



	/* Has the flow change ? */

	if (txq->flow.as_int != txp->flow.as_int)

		(void)hfi1_ipoib_flush_tx_list(dev, txq);

	if (txq->flow.as_int != txp->flow.as_int) {

		int ret;



		ret = hfi1_ipoib_flush_tx_list(dev, txq);

		if (unlikely(ret)) {

			if (ret == -EBUSY)

				++dev->stats.tx_dropped;

			dev_kfree_skb_any(skb);

			return NETDEV_TX_OK;

		}

	}

	tx = hfi1_ipoib_send_dma_common(dev, skb, txp);

	if (IS_ERR(tx)) {

		int ret = PTR_ERR(tx);
@@ -612,6 +610,9 @@ static int hfi1_ipoib_sdma_sleep(struct sdma_engine *sde, 


		netif_stop_subqueue(txq->priv->netdev, txq->q_idx);



		if (list_empty(&txreq->list))

			/* came from non-list submit */

			list_add_tail(&txreq->list, &txq->tx_list);

		if (list_empty(&txq->wait.list))

			iowait_queue(pkts_sent, wait->iow, &sde->dmawait);

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