net/mlx4_en: Fix a race when closing TX queue (72259225) · Commits · e / devices / android_kernel_xiaomi_markw

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. CC: Eric Dumazet <edumazet@google.com> Signed-off-by:

Yevgeny Petrilin <yevgenyp@mellanox.com> Signed-off-by:

Eugenia Emantayev <eugenia@mellanox.com> Signed-off-by:

Amir Vadai <amirv@mellanox.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/en_tx.c

+15 −1

Original line number	Diff line number	Diff line
		@@ -588,8 +588,22 @@ 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++;

		/* If queue was emptied after the if, and before the
		* stop_queue - need to wake the queue, or else it will remain
		* stopped forever.
		* Need a memory barrier to make sure ring->cons was not
		* updated before queue was stopped.
		*/
		wmb();

		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 */
		AVG_PERF_COUNTER(priv->pstats.inflight_avg,