netdev - Re: Disable TX path on eth I/F from driver?

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Date: Fri, 30 Jun 2023 18:50:12 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Joakim Tjernlund <Joakim.Tjernlund@...inera.com>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: Disable TX path on eth I/F from driver?

On Fri, Jun 30, 2023 at 03:48:15PM +0000, Joakim Tjernlund wrote:
> We have a few eth I/F that is for monitoring only, if any TX one gets:
> NETDEV WATCHDOG: trap0 (xr-ccip): transmit queue 0 timed out
> [   55.903074] WARNING: CPU: 0 PID: 0 at net/sched/sch_generic.c:477 dev_watchdog+0x138/0x160
> [   55.911380] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.15.109-00161-g1268ae25c302-dirty #7
> <long trace snipped>
> 
> I would like to, from within the driver, disable the TX path so the IP stack cannot TX any
> pkgs but cannot find a way to do so.
> Is there a way(to at least avid the NETDEV WATCHDOG msg) disable TX?
> On kernel 5.15

Have you tried using TC or iptables to just unconditionally drop all
packets?

	Andrew