[PATCH net] 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 <redacted>
---
 drivers/net/tun.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index fecc9a1d293a..1572878c3403 100644
--- 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);

-- 
2.33.0

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller [off-list ref]:

On Fri, 12 Nov 2021 08:56:03 +0100 you wrote:

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.

[...]

Here is the summary with links:
  - [net] tun: fix bonding active backup with arp monitoring
    https://git.kernel.org/netdev/net/c/a31d27fbed5d

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Le 15/11/2021 à 14:10, patchwork-bot+netdevbpf@kernel.org a écrit :

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller [off-list ref]:

On Fri, 12 Nov 2021 08:56:03 +0100 you wrote:

quoted

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.

[...]

Here is the summary with links:
  - [net] tun: fix bonding active backup with arp monitoring
    https://git.kernel.org/netdev/net/c/a31d27fbed5d

You are awesome, thank you!

May I ask for a backport to stable of this patch?

It's now in Linus tree: a31d27fbed5d ("tun: fix bonding active backup with arp
monitoring"):
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a31d27fbed5d

I didn't put a Fixes tag in the original submission because the bug is there
before git ages.
Maybe "Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")" would have been a better choice.


Regards,
Nicolas

On Fri, Nov 19, 2021 at 06:26:17PM +0100, Nicolas Dichtel wrote:

Le 15/11/2021 à 14:10, patchwork-bot+netdevbpf@kernel.org a écrit :

quoted

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller [off-list ref]:

On Fri, 12 Nov 2021 08:56:03 +0100 you wrote:

quoted

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.

[...]

Here is the summary with links:
  - [net] tun: fix bonding active backup with arp monitoring
    https://git.kernel.org/netdev/net/c/a31d27fbed5d

You are awesome, thank you!

May I ask for a backport to stable of this patch?

It's now in Linus tree: a31d27fbed5d ("tun: fix bonding active backup with arp
monitoring"):
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a31d27fbed5d

I didn't put a Fixes tag in the original submission because the bug is there
before git ages.
Maybe "Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")" would have been a better choice.

Now queued up, thanks.

greg k-h