net: axienet: Fix race condition causing TX hang (7de44285) · Commits · 戴 / test

It is possible that the interrupt handler fires and frees up space in the TX ring in between checking for sufficient TX ring space and stopping the TX queue in axienet_start_xmit. If this happens, the queue wake from the interrupt handler will occur before the queue is stopped, causing a lost wakeup and the adapter's transmit hanging. To avoid this, after stopping the queue, check again whether there is sufficient space in the TX ring. If so, wake up the queue again. Signed-off-by:

Robert Hancock <hancock@sedsystems.ca> Signed-off-by:

David S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

+17 −3

Original line number	Diff line number	Diff line
		@@ -622,6 +622,10 @@ static void axienet_start_xmit_done(struct net_device *ndev)

		ndev->stats.tx_packets += packets;
		ndev->stats.tx_bytes += size;

		/* Matches barrier in axienet_start_xmit */
		smp_mb();

		netif_wake_queue(ndev);
		}

		@@ -677,9 +681,19 @@ axienet_start_xmit(struct sk_buff skb, struct net_device ndev)
		cur_p = &lp->tx_bd_v[lp->tx_bd_tail];

		if (axienet_check_tx_bd_space(lp, num_frag)) {
		if (!netif_queue_stopped(ndev))
		if (netif_queue_stopped(ndev))
		return NETDEV_TX_BUSY;

		netif_stop_queue(ndev);

		/* Matches barrier in axienet_start_xmit_done */
		smp_mb();

		/* Space might have just been freed - check again */
		if (axienet_check_tx_bd_space(lp, num_frag))
		return NETDEV_TX_BUSY;

		netif_wake_queue(ndev);
		}

		if (skb->ip_summed == CHECKSUM_PARTIAL) {

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