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: d99dc602e2a5 ("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: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/hw/hfi1/ipoib_tx.c b/drivers/infiniband/hw/hfi1/ipoib_tx.c
index 175290c..76dcb56 100644 (file)
--- a/drivers/infiniband/hw/hfi1/ipoib_tx.c
+++ b/drivers/infiniband/hw/hfi1/ipoib_tx.c
@@ -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);