[PATCH 6.18 405/752] net: usb: kaweth: remove TX queue manipulation in kaweth_set_rx_mode

Sasha Levin
2026-02-28T17:53:47Z

From: Ziyi Guo <n7l8m4@u.northwestern.edu>

[ Upstream commit 64868f5ecadeb359a49bc4485bfa7c497047f13a ]

kaweth_set_rx_mode(), the ndo_set_rx_mode callback, calls
netif_stop_queue() and netif_wake_queue(). These are TX queue flow
control functions unrelated to RX multicast configuration.

The premature netif_wake_queue() can re-enable TX while tx_urb is still
in-flight, leading to a double usb_submit_urb() on the same URB:

kaweth_start_xmit() {
netif_stop_queue();
usb_submit_urb(kaweth->tx_urb);
}

kaweth_set_rx_mode() {
netif_stop_queue();
netif_wake_queue(); // wakes TX queue before URB is done
}

kaweth_start_xmit() {
netif_stop_queue();
usb_submit_urb(kaweth->tx_urb); // URB submitted while active
}

This triggers the WARN in usb_submit_urb():

"URB submitted while active"

This is a similar class of bug fixed in rtl8150 by

- commit 958baf5eaee3 ("net: usb: Remove disruptive netif_wake_queue in rtl8150_set_multicast").

Also kaweth_set_rx_mode() is already functionally broken, the
real set_rx_mode action is performed by kaweth_async_set_rx_mode(),
which in turn is not a no-op only at ndo_open() time.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Ziyi Guo <n7l8m4@u.northwestern.edu>
Link: https://patch.msgid.link/20260217175012.1234494-1-n7l8m4@u.northwestern.edu
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/usb/kaweth.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/drivers/net/usb/kaweth.c b/drivers/net/usb/kaweth.c
index c9efb7df892ec..e01d14f6c3667 100644
--- a/drivers/net/usb/kaweth.c
+++ b/drivers/net/usb/kaweth.c
@@ -765,7 +765,6 @@ static void kaweth_set_rx_mode(struct net_device *net)

netdev_dbg(net, "Setting Rx mode to %d\n", packet_filter_bitmap);

- netif_stop_queue(net);

if (net->flags & IFF_PROMISC) {
packet_filter_bitmap |= KAWETH_PACKET_FILTER_PROMISCUOUS;
@@ -775,7 +774,6 @@ static void kaweth_set_rx_mode(struct net_device *net)
}

kaweth->packet_filter_bitmap = packet_filter_bitmap;
- netif_wake_queue(net);
}

/****************************************************************
--
2.51.0