tun: fix bonding active backup with arp monitoring

As stated in the bonding doc, trans_start must be set manually for drivers
using NETIF_F_LLTX:
 Drivers that use NETIF_F_LLTX flag must also update
 netdev_queue->trans_start. If they do not, then the ARP monitor will
 immediately fail any slaves using that driver, and those slaves will stay
 down.

Link: https://www.kernel.org/doc/html/v5.15/networking/bonding.html#arp-monitor-operation
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index fecc9a1..1572878 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1010,6 +1010,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
 {
        struct tun_struct *tun = netdev_priv(dev);
        int txq = skb->queue_mapping;
+       struct netdev_queue *queue;
        struct tun_file *tfile;
        int len = skb->len;
 
@@ -1054,6 +1055,10 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
        if (ptr_ring_produce(&tfile->tx_ring, skb))
                goto drop;
 
+       /* NETIF_F_LLTX requires to do our own update of trans_start */
+       queue = netdev_get_tx_queue(dev, txq);
+       queue->trans_start = jiffies;
+
        /* Notify and wake up reader process */
        if (tfile->flags & TUN_FASYNC)
                kill_fasync(&tfile->fasync, SIGIO, POLL_IN);