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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@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yevgeny Petrilin 2012-08-03 00:38:37 +00:00 committed by David S. Miller
parent c8c40b7f32
commit c18520bd1b
2 changed files with 7 additions and 11 deletions
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17
drivers/net/ethernet/mellanox/mlx4/en_tx.c
View File

@ -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;

1
drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
View File

@ -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;