Commit 7de44285 authored by Robert Hancock's avatar Robert Hancock Committed by David S. Miller

net: axienet: Fix race condition causing TX hang

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: default avatarRobert Hancock <hancock@sedsystems.ca>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 522856ce
...@@ -622,6 +622,10 @@ static void axienet_start_xmit_done(struct net_device *ndev) ...@@ -622,6 +622,10 @@ static void axienet_start_xmit_done(struct net_device *ndev)
ndev->stats.tx_packets += packets; ndev->stats.tx_packets += packets;
ndev->stats.tx_bytes += size; ndev->stats.tx_bytes += size;
/* Matches barrier in axienet_start_xmit */
smp_mb();
netif_wake_queue(ndev); netif_wake_queue(ndev);
} }
...@@ -677,9 +681,19 @@ axienet_start_xmit(struct sk_buff *skb, struct net_device *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]; cur_p = &lp->tx_bd_v[lp->tx_bd_tail];
if (axienet_check_tx_bd_space(lp, num_frag)) { if (axienet_check_tx_bd_space(lp, num_frag)) {
if (!netif_queue_stopped(ndev)) if (netif_queue_stopped(ndev))
netif_stop_queue(ndev); return NETDEV_TX_BUSY;
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) { if (skb->ip_summed == CHECKSUM_PARTIAL) {
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment