mlx4_en: Removed TX locking when polling TX cq

There is no need to synchronize the polling with the transmit
function. The only place to synchronize is when we process
the cq from the transmit function. Also removed spin_lock_irq,
and using spin_trylock, if somebody else is already processing the cq,
no need to wait for it to finish.

Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/mlx4/en_tx.c b/drivers/net/mlx4/en_tx.c
index 8592f8f..1f25821 100644
--- a/drivers/net/mlx4/en_tx.c
+++ b/drivers/net/mlx4/en_tx.c
@@ -404,14 +404,12 @@
 	struct mlx4_en_priv *priv = netdev_priv(cq->dev);
 	struct mlx4_en_tx_ring *ring = &priv->tx_ring[cq->ring];
 
-	spin_lock_irq(&ring->comp_lock);
 	cq->armed = 0;
+	if (!spin_trylock(&ring->comp_lock))
+		return;
 	mlx4_en_process_tx_cq(cq->dev, cq);
-	if (ring->blocked)
-		mlx4_en_arm_cq(priv, cq);
-	else
-		mod_timer(&cq->timer, jiffies + 1);
-	spin_unlock_irq(&ring->comp_lock);
+	mod_timer(&cq->timer, jiffies + 1);
+	spin_unlock(&ring->comp_lock);
 }
 
 
@@ -424,8 +422,10 @@
 
 	INC_PERF_COUNTER(priv->pstats.tx_poll);
 
-	netif_tx_lock(priv->dev);
-	spin_lock_irq(&ring->comp_lock);
+	if (!spin_trylock(&ring->comp_lock)) {
+		mod_timer(&cq->timer, jiffies + MLX4_EN_TX_POLL_TIMEOUT);
+		return;
+	}
 	mlx4_en_process_tx_cq(cq->dev, cq);
 	inflight = (u32) (ring->prod - ring->cons - ring->last_nr_txbb);
 
@@ -435,8 +435,7 @@
 	if (inflight && priv->port_up)
 		mod_timer(&cq->timer, jiffies + MLX4_EN_TX_POLL_TIMEOUT);
 
-	spin_unlock_irq(&ring->comp_lock);
-	netif_tx_unlock(priv->dev);
+	spin_unlock(&ring->comp_lock);
 }
 
 static struct mlx4_en_tx_desc *mlx4_en_bounce_to_desc(struct mlx4_en_priv *priv,
@@ -479,7 +478,10 @@
 
 	/* Poll the CQ every mlx4_en_TX_MODER_POLL packets */
 	if ((++ring->poll_cnt & (MLX4_EN_TX_POLL_MODER - 1)) == 0)
-		mlx4_en_process_tx_cq(priv->dev, cq);
+		if (spin_trylock(&ring->comp_lock)) {
+			mlx4_en_process_tx_cq(priv->dev, cq);
+			spin_unlock(&ring->comp_lock);
+		}
 }
 
 static void *get_frag_ptr(struct sk_buff *skb)