1 files changed, 14 insertions, 3 deletions

diff --git a/drivers/net/sfc/tx.c b/drivers/net/sfc/tx.c
index 03194f7c0954..bdb92b4af683 100644
--- a/drivers/net/sfc/tx.c
+++ b/drivers/net/sfc/tx.c
@@ -240,8 +240,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
                                  * of read_count. */
                                 smp_mb();
                                 tx_queue->old_read_count =
-                                        *(volatile unsigned *)
-                                        &tx_queue->read_count;
+                                        ACCESS_ONCE(tx_queue->read_count);
                                 fill_level = (tx_queue->insert_count
                                               - tx_queue->old_read_count);
                                 q_space = efx->txq_entries - 1 - fill_level;
@@ -429,6 +428,16 @@ void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
                         __netif_tx_unlock(queue);
                 }
         }
+
+        /* Check whether the hardware queue is now empty */
+        if ((int)(tx_queue->read_count - tx_queue->old_write_count) >= 0) {
+                tx_queue->old_write_count = ACCESS_ONCE(tx_queue->write_count);
+                if (tx_queue->read_count == tx_queue->old_write_count) {
+                        smp_mb();
+                        tx_queue->empty_read_count =
+                                tx_queue->read_count | EFX_EMPTY_COUNT_VALID;
+                }
+        }
 }
 
 int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
@@ -474,8 +483,10 @@ void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
 
         tx_queue->insert_count = 0;
         tx_queue->write_count = 0;
+        tx_queue->old_write_count = 0;
         tx_queue->read_count = 0;
         tx_queue->old_read_count = 0;
+        tx_queue->empty_read_count = 0 | EFX_EMPTY_COUNT_VALID;
         BUG_ON(tx_queue->stopped);
 
         /* Set up TX descriptor ring */
@@ -764,7 +775,7 @@ static int efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
                          * stopped from the access of read_count. */
                         smp_mb();
                         tx_queue->old_read_count =
-                                *(volatile unsigned *)&tx_queue->read_count;
+                                ACCESS_ONCE(tx_queue->read_count);
                         fill_level = (tx_queue->insert_count
                                       - tx_queue->old_read_count);
                         q_space = efx->txq_entries - 1 - fill_level;