[PATCH] usbnet_link_change() fails to call netif_carrier_on()
From: Krzysztof Hałasa
Date: Tue Nov 19 2024 - 08:55:28 EST
Hi,
ASIX AX88772B based USB 10/100 Ethernet adapter doesn't come
up ("carrier off"), despite the built-in 100BASE-FX PHY positive link
indication.
The problem appears to be in usbnet.c framework:
void usbnet_link_change(struct usbnet *dev, bool link, bool need_reset)
{
/* update link after link is reseted */
if (link && !need_reset)
netif_carrier_on(dev->net);
else
netif_carrier_off(dev->net);
if (need_reset && link)
usbnet_defer_kevent(dev, EVENT_LINK_RESET);
else
usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
}
I think the author's idea was a bit different than what the code really
ended doing. Especially when called with link = 1 and need_reset = 1.
It seems it may have already caused problems - possible workarounds:
- commit 7be4cb7189f7 ("net: usb: ax88179_178a: improve reset check")
- commit ecf848eb934b ("net: usb: ax88179_178a: fix link status when
link is set to down/up")
Can't check those due to -ENOHW but ax88179_link_reset() adds
a netif_carrier_on() call on link ups.
Not sure about the "reset" name, though (and the comment in
usbnet_link_change()). It seems it's when the link goes up.
Signed-off-by: Krzysztof Hałasa <khalasa@xxxxxxx>
Fixes: ac64995da872 ("usbnet: introduce usbnet_link_change API")
Fixes: 4b49f58fff00 ("usbnet: handle link change")
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1978,16 +1978,18 @@ EXPORT_SYMBOL(usbnet_manage_power);
void usbnet_link_change(struct usbnet *dev, bool link, bool need_reset)
{
- /* update link after link is reseted */
- if (link && !need_reset)
+ if (link)
netif_carrier_on(dev->net);
else
netif_carrier_off(dev->net);
- if (need_reset && link)
- usbnet_defer_kevent(dev, EVENT_LINK_RESET);
- else
- usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
+ if (need_reset) {
+ /* update link after link is reset */
+ if (link)
+ usbnet_defer_kevent(dev, EVENT_LINK_RESET);
+ else
+ usbnet_defer_kevent(dev, EVENT_LINK_CHANGE);
+ }
}
EXPORT_SYMBOL(usbnet_link_change);
The code has been introduced in 2013, by 4b49f58fff00 and a bunch of
related commits. Perhaps it visibly affects only AXIS and dm9601
adapters, though.
--
Krzysztof "Chris" Hałasa
Sieć Badawcza Łukasiewicz
Przemysłowy Instytut Automatyki i Pomiarów PIAP
Al. Jerozolimskie 202, 02-486 Warszawa