path: root/drivers
diff options
authorEsben Haabendal <esben@geanix.com>2020-02-21 07:47:21 +0100
committerDavid S. Miller <davem@davemloft.net>2020-02-24 10:58:48 -0800
commit84823ff80f7403752b59e00bb198724100dc611c (patch)
treee8a373a6d314a81b514f23a20a00b3f1e82855be /drivers
parentnet: core: devlink.c: Hold devlink->lock from the beginning of devlink_dpipe_table_register() (diff)
net: ll_temac: 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 temac_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. This is a port of the similar fix in axienet driver, commit 7de44285c1f6 ("net: axienet: Fix race condition causing TX hang"). Fixes: 23ecc4bde21f ("net: ll_temac: fix checksum offload logic") Signed-off-by: Esben Haabendal <esben@geanix.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
1 files changed, 16 insertions, 3 deletions
diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c
index 6f11f52c9a9e..996004ef8bd4 100644
--- a/drivers/net/ethernet/xilinx/ll_temac_main.c
+++ b/drivers/net/ethernet/xilinx/ll_temac_main.c
@@ -788,6 +788,9 @@ static void temac_start_xmit_done(struct net_device *ndev)
stat = be32_to_cpu(cur_p->app0);
+ /* Matches barrier in temac_start_xmit */
+ smp_mb();
@@ -830,9 +833,19 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev)
cur_p = &lp->tx_bd_v[lp->tx_bd_tail];
if (temac_check_tx_bd_space(lp, num_frag + 1)) {
- 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 temac_start_xmit_done */
+ smp_mb();
+ /* Space might have just been freed - check again */
+ if (temac_check_tx_bd_space(lp, num_frag))
+ return NETDEV_TX_BUSY;
+ netif_wake_queue(ndev);
cur_p->app0 = 0;