From: Jay Vosburgh <jay.vosburgh@canonical.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
netdev@vger.kernel.org, Jonathan Toppins <jtoppins@redhat.com>,
Veaceslav Falico <vfalico@gmail.com>,
Andy Gospodarek <andy@greyhouse.net>
Subject: Re: [PATCH net] veth: Add updating of trans_start
Date: Fri, 17 Jun 2022 09:42:55 -0700 [thread overview]
Message-ID: <5765.1655484175@famine> (raw)
In-Reply-To: <20220617084535.6d687ed0@kernel.org>
Jakub Kicinski <kuba@kernel.org> wrote:
>On Thu, 16 Jun 2022 12:26:30 -0700 Jay Vosburgh wrote:
>> Since commit 21a75f0915dd ("bonding: Fix ARP monitor validation"),
>> the bonding ARP / ND link monitors depend on the trans_start time to
>> determine link availability. NETIF_F_LLTX drivers must update trans_start
>> directly, which veth does not do. This prevents use of the ARP or ND link
>> monitors with veth interfaces in a bond.
>
>Why is a SW device required to update its trans_start? trans_start is
>for the Tx hang watchdog, AFAIK, not a general use attribute. There's
>plenty of NETIF_F_LLTX devices, are they all broken?
In this case, it's to permit the bonding ARP / ND monitor to
function if that software device (veth in this case) is added to a bond
using the ARP / ND monitor (which relies on trans_start, and has done so
since at least 2.6.0). I'll agree it's a niche case; this was broken
for veth for quite some time, but veth + netns is handy for software
only test cases, so it seems worth doing.
I didn't exhaustively check all LLTX drivers, but, e.g., tun
does update trans_start:
drivers/net/tun.c:
/* NETIF_F_LLTX requires to do our own update of trans_start */
queue = netdev_get_tx_queue(dev, txq);
txq_trans_cond_update(queue);
-J
---
-Jay Vosburgh, jay.vosburgh@canonical.com
next prev parent reply other threads:[~2022-06-17 16:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-16 19:26 [PATCH net] veth: Add updating of trans_start Jay Vosburgh
2022-06-17 10:40 ` patchwork-bot+netdevbpf
2022-06-17 15:45 ` Jakub Kicinski
2022-06-17 16:42 ` Jay Vosburgh [this message]
2022-06-17 19:44 ` Jakub Kicinski
2022-06-18 0:27 ` Jay Vosburgh
2022-06-18 0:55 ` Jakub Kicinski
2022-06-21 19:52 ` Jakub Kicinski
2022-06-22 1:42 ` Jay Vosburgh
2022-06-22 4:38 ` Jakub Kicinski
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