From patchwork Thu Jan 17 11:47:20 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [net-next,V1,5/6] net/mlx4_en: Fix a race when closing TX queue Date: Thu, 17 Jan 2013 01:47:20 -0000 From: Amir Vadai X-Patchwork-Id: 213222 Message-Id: <1358423241-2452-6-git-send-email-amirv@mellanox.com> To: "David S. Miller" Cc: netdev@vger.kernel.org, Or Gerlitz , Amir Vadai , Yevgeny Petrilin , Eugenia Emantayev There is a possible race where the TX completion handler can clean the entire TX queue between the decision that the queue is full and actually closing it. To avoid this situation, check again if the queue is really full, if not, reopen the transmit and continue with sending the packet. Signed-off-by: Yevgeny Petrilin Signed-off-by: Eugenia Emantayev Signed-off-by: Amir Vadai --- drivers/net/ethernet/mellanox/mlx4/en_tx.c | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c index 2b799f4..1d17f5f 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c @@ -592,7 +592,14 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) netif_tx_stop_queue(ring->tx_queue); priv->port_stats.queue_stopped++; - return NETDEV_TX_BUSY; + /* Check again whether the queue was cleaned */ + if (unlikely(((int)(ring->prod - ring->cons)) <= + ring->size - HEADROOM - MAX_DESC_TXBBS)) { + netif_tx_wake_queue(ring->tx_queue); + priv->port_stats.wake_queue++; + } else { + return NETDEV_TX_BUSY; + } } /* Track current inflight packets for performance analysis */