net/mlx5e: Fix xmit_more counter race issue

Update the xmit_more counter before notifying the HW,
to prevent a possible use-after-free of the skb.

Fixes: c8cf78fe100b ("net/mlx5e: Add ethtool counter for TX xmit_more")
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/en_tx.c

@@ -356,6 +356,7 @@ static netdev_tx_t mlx5e_sq_xmit(struct mlx5e_sq *sq, struct sk_buff *skb)
 		sq->stats.stopped++;
 	}
 
+	sq->stats.xmit_more += skb->xmit_more;
 	if (!skb->xmit_more || netif_xmit_stopped(sq->txq)) {
 		int bf_sz = 0;
 
@@ -375,7 +376,6 @@ static netdev_tx_t mlx5e_sq_xmit(struct mlx5e_sq *sq, struct sk_buff *skb)
 
 	sq->stats.packets++;
 	sq->stats.bytes += num_bytes;
-	sq->stats.xmit_more += skb->xmit_more;
 	return NETDEV_TX_OK;
 
 dma_unmap_wqe_err: