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Message-Id: <20250806003105.15172-1-ammarfaizi2@gnuweeb.org>
Date: Wed, 6 Aug 2025 07:31:05 +0700
From: Ammar Faizi <ammarfaizi2@...weeb.org>
To: Oliver Neukum <oneukum@...e.com>,
Andrew Lunn <andrew+netdev@...n.ch>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Ammar Faizi <ammarfaizi2@...weeb.org>,
Simon Horman <horms@...nel.org>,
John Ernberg <john.ernberg@...ia.se>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Linux Netdev Mailing List <netdev@...r.kernel.org>,
Linux USB Mailing List <linux-usb@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Armando Budianto <sprite@...weeb.org>,
gwml@...r.gnuweeb.org,
stable@...r.kernel.org
Subject: [PATCH net v3] net: usbnet: Fix the wrong netif_carrier_on() call
The commit referenced in the Fixes tag causes usbnet to malfunction
(identified via git bisect). Post-commit, my external RJ45 LAN cable
fails to connect. Linus also reported the same issue after pulling that
commit.
The code has a logic error: netif_carrier_on() is only called when the
link is already on. Fix this by moving the netif_carrier_on() call
outside the if-statement entirely. This ensures it is always called
when EVENT_LINK_CARRIER_ON is set and properly clears it regardless
of the link state.
Cc: stable@...r.kernel.org
Cc: Armando Budianto <sprite@...weeb.org>
Reviewed-by: Simon Horman <horms@...nel.org>
Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
Link: https://lore.kernel.org/all/CAHk-=wjqL4uF0MG_c8+xHX1Vv8==sPYQrtzbdA3kzi96284nuQ@mail.gmail.com
Closes: https://lore.kernel.org/netdev/CAHk-=wjKh8X4PT_mU1kD4GQrbjivMfPn-_hXa6han_BTDcXddw@mail.gmail.com
Closes: https://lore.kernel.org/netdev/0752dee6-43d6-4e1f-81d2-4248142cccd2@gnuweeb.org
Fixes: 0d9cfc9b8cb1 ("net: usbnet: Avoid potential RCU stall on LINK_CHANGE event")
Signed-off-by: Ammar Faizi <ammarfaizi2@...weeb.org>
---
v3:
- Move the netif_carrier_on() call outside of the if-statement
entirely (Linus).
v2:
- Rebase on top of the latest netdev/net tree. The previous patch was
based on 0d9cfc9b8cb1. Line numbers have changed since then.
Link: https://lore.gnuweeb.org/gwml/20250801190310.58443-1-ammarfaizi2@gnuweeb.org
drivers/net/usb/usbnet.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index a38ffbf4b3f0..511c4154cf74 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1113,32 +1113,32 @@ static const struct ethtool_ops usbnet_ethtool_ops = {
.set_link_ksettings = usbnet_set_link_ksettings_mii,
};
/*-------------------------------------------------------------------------*/
static void __handle_link_change(struct usbnet *dev)
{
if (!test_bit(EVENT_DEV_OPEN, &dev->flags))
return;
+ if (test_and_clear_bit(EVENT_LINK_CARRIER_ON, &dev->flags))
+ netif_carrier_on(dev->net);
+
if (!netif_carrier_ok(dev->net)) {
/* kill URBs for reading packets to save bus bandwidth */
unlink_urbs(dev, &dev->rxq);
/*
* tx_timeout will unlink URBs for sending packets and
* tx queue is stopped by netcore after link becomes off
*/
} else {
- if (test_and_clear_bit(EVENT_LINK_CARRIER_ON, &dev->flags))
- netif_carrier_on(dev->net);
-
/* submitting URBs for reading packets */
queue_work(system_bh_wq, &dev->bh_work);
}
/* hard_mtu or rx_urb_size may change during link change */
usbnet_update_max_qlen(dev);
clear_bit(EVENT_LINK_CHANGE, &dev->flags);
}
--
Ammar Faizi
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