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authorRobert Hancock <hancock@sedsystems.ca>2019-06-07 01:28:17 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-07-26 10:14:04 +0300
commita76f32cbd38c6bf6cfe841c2916ded1ad371eaa5 (patch)
treecda9952cd727612b0240a53333e2741b6154e843
parent9d643358386d46c261e000a93f5eb28dd8009e33 (diff)
downloadlinux-a76f32cbd38c6bf6cfe841c2916ded1ad371eaa5.tar.xz
net: axienet: Fix race condition causing TX hang
[ Upstream commit 7de44285c1f69ccfbe8be1d6a16fcd956681fee6 ] 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> Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--drivers/net/ethernet/xilinx/xilinx_axienet_main.c20
1 files changed, 17 insertions, 3 deletions
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 7cfd7ff38e86..66b30ebd45ee 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -614,6 +614,10 @@ 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);
}
@@ -668,9 +672,19 @@ static int 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))
- netif_stop_queue(ndev);
- return NETDEV_TX_BUSY;
+ 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) {