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Date: Fri, 3 Aug 2012 13:38:37 +0300 From: Yevgeny Petrilin <yevgenyp@...lanox.co.il> To: davem@...emloft.net Cc: netdev@...r.kernel.org, Yevgeny Petrilin <yevgenyp@...lanox.co.il> Subject: [PATCH V1 2/3] 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@...lanox.co.il> --- 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 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 @@ 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 5f1ab10..9d27e42 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; -- 1.7.7 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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