From c18520bd1b244fe8e3ac5358137321780a70d6e7 Mon Sep 17 00:00:00 2001 From: Yevgeny Petrilin Date: Fri, 3 Aug 2012 00:38:37 +0000 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- drivers/net/ethernet/mellanox/mlx4/en_tx.c | 17 +++++++---------- drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 1 - 2 files changed, 7 insertions(+), 11 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c index 019d856b1334..10bba09c44ea 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c @@ -164,7 +164,6 @@ int mlx4_en_activate_tx_ring(struct mlx4_en_priv *priv, 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 @@ static void mlx4_en_process_tx_cq(struct net_device *dev, struct mlx4_en_cq *cq) 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 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev) 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; diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h index 5f1ab105debc..9d27e42264e2 100644 --- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h @@ -248,7 +248,6 @@ struct mlx4_en_tx_ring { u32 doorbell_qpn; void *buf; u16 poll_cnt; - int blocked; struct mlx4_en_tx_info *tx_info; u8 *bounce_buf; u32 last_nr_txbb; -- 2.20.1