Re: [PATCH net] net: watchdog: hold device global xmit lock during tx disable

On Fri,  5 Feb 2021 17:37:32 -0800 Edwin Peer wrote:

Prevent netif_tx_disable() running concurrently with dev_watchdog() by
taking the device global xmit lock. Otherwise, the recommended:

	netif_carrier_off(dev);
	netif_tx_disable(dev);

driver shutdown sequence can happen after the watchdog has already
checked carrier, resulting in possible false alarms. This is because
netif_tx_lock() only sets the frozen bit without maintaining the locks
on the individual queues.

Fixes: c3f26a269c24 ("netdev: Fix lockdep warnings in multiqueue configurations.")
Signed-off-by: Edwin Peer <redacted>

Reviewed-by: Jakub Kicinski <kuba@kernel.org>

Even though using the dev->tx_global_lock as a barrier is not very
clean in itself the thinking is that this restores previous semantics
with deeper changes.