net/mlx4_en: Fixing TX queue stop/wake flow
Removing the ring->blocked flag, it is redundant and leads to a race:
We close the TX queue and then set the "blocked" flag.
Between those 2 operations the completion function can check the "blocked"
flag, sees that it is 0, and wouldn't open the TX queue.
Using netif_tx_queue_stopped to check the state of the queue to avoid this race.
Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
index 019d856..10bba09 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
@@ -164,7 +164,6 @@
ring->cons = 0xffffffff;
ring->last_nr_txbb = 1;
ring->poll_cnt = 0;
- ring->blocked = 0;
memset(ring->tx_info, 0, ring->size * sizeof(struct mlx4_en_tx_info));
memset(ring->buf, 0, ring->buf_size);
@@ -365,14 +364,13 @@
ring->cons += txbbs_skipped;
netdev_tx_completed_queue(ring->tx_queue, packets, bytes);
- /* Wakeup Tx queue if this ring stopped it */
- if (unlikely(ring->blocked)) {
- if ((u32) (ring->prod - ring->cons) <=
- ring->size - HEADROOM - MAX_DESC_TXBBS) {
- ring->blocked = 0;
- netif_tx_wake_queue(ring->tx_queue);
- priv->port_stats.wake_queue++;
- }
+ /*
+ * Wakeup Tx queue if this stopped, and at least 1 packet
+ * was completed
+ */
+ if (netif_tx_queue_stopped(ring->tx_queue) && txbbs_skipped > 0) {
+ netif_tx_wake_queue(ring->tx_queue);
+ priv->port_stats.wake_queue++;
}
}
@@ -592,7 +590,6 @@
ring->size - HEADROOM - MAX_DESC_TXBBS)) {
/* every full Tx ring stops queue */
netif_tx_stop_queue(ring->tx_queue);
- ring->blocked = 1;
priv->port_stats.queue_stopped++;
return NETDEV_TX_BUSY;