[PATCH] net: usb: asix: avoid to call phylink_stop() a second time

[Xu Yang <xu.yang_2@nxp.com>]

The kernel will have below dump when system resume if the USB net device
was already disconnected during system suspend.

[   46.392207] ------------[ cut here ]------------
[   46.392216] called from state HALTED
[   46.392255] WARNING: CPU: 0 PID: 56 at drivers/net/phy/phy.c:1630 phy_stop+0x12c/0x194
[   46.392272] Modules linked in:
[   46.392281] CPU: 0 UID: 0 PID: 56 Comm: kworker/0:3 Not tainted 6.15.0-rc7-next-20250523-06664-ga6888feb9f45-dirty #311 PREEMPT
[   46.392287] Hardware name: NXP i.MX93 11X11 EVK board (DT)
[   46.392291] Workqueue: usb_hub_wq hub_event
[   46.392301] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   46.392306] pc : phy_stop+0x12c/0x194
[   46.392311] lr : phy_stop+0x12c/0x194
[   46.392315] sp : ffff8000828fb720
[   46.392317] x29: ffff8000828fb720 x28: ffff000005558b50 x27: ffff00000555b400
[   46.392324] x26: ffff000004e4f000 x25: ffff00000557f800 x24: 0000000000000000
[   46.392331] x23: 0000000000000000 x22: ffff8000817eea10 x21: ffff000004fc5000
[   46.392338] x20: ffff000004fc5a00 x19: ffff0000056eb000 x18: fffffffffffeb3c0
[   46.392345] x17: ffff7ffffdc3c000 x16: ffff800080000000 x15: 0000000000000000
[   46.392352] x14: 0000000000000000 x13: 206574617473206d x12: ffff800082057068
[   46.392359] x11: 0000000000000058 x10: 0000000000000018 x9 : ffff800082057068
[   46.392366] x8 : 0000000000000264 x7 : ffff8000820af068 x6 : ffff8000820af068
[   46.392373] x5 : ffff00007fb80308 x4 : 0000000000000000 x3 : ffff7ffffdc3c000
[   46.392379] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff000004ed4600
[   46.392386] Call trace:
[   46.392390]  phy_stop+0x12c/0x194 (P)
[   46.392396]  phylink_stop+0x28/0x114
[   46.392404]  ax88772_stop+0x18/0x28
[   46.392411]  usbnet_stop+0x80/0x230
[   46.392418]  __dev_close_many+0xb4/0x1e0
[   46.392427]  dev_close_many+0x88/0x140
[   46.392434]  unregister_netdevice_many_notify+0x1b8/0xa10
[   46.392440]  unregister_netdevice_queue+0xe0/0xe8
[   46.392445]  unregister_netdev+0x24/0x50
[   46.392450]  usbnet_disconnect+0x50/0x124
[   46.392457]  usb_unbind_interface+0x78/0x2b4
[   46.392463]  device_remove+0x70/0x80
[   46.392470]  device_release_driver_internal+0x1cc/0x224
[   46.392475]  device_release_driver+0x18/0x30
[   46.392480]  bus_remove_device+0xc8/0x108
[   46.392488]  device_del+0x14c/0x420
[   46.392495]  usb_disable_device+0xe4/0x1c0
[   46.392502]  usb_disconnect+0xd8/0x2ac
[   46.392508]  hub_event+0x91c/0x1580
[   46.392514]  process_one_work+0x148/0x290
[   46.392523]  worker_thread+0x2c8/0x3e4
[   46.392530]  kthread+0x12c/0x204
[   46.392536]  ret_from_fork+0x10/0x20
[   46.392545] ---[ end trace 0000000000000000 ]---

It's because usb_resume_interface() will be skipped if the USB core found
the USB device was already disconnected. In this case, asix_resume() will
not be called anymore. So asix_suspend/resume() can't be balanced. When
ax88772_stop() is called, the phy device was already stopped. To avoid
calling phylink_stop() a second time, check whether usb net device is
already in suspend state.

Fixes: e0bffe3e6894 ("net: asix: ax88772: migrate to phylink")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
---
 drivers/net/usb/asix_devices.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/usb/asix_devices.c b/drivers/net/usb/asix_devices.c
index 9b0318fb50b5..ac28f5fe7ac2 100644
--- a/drivers/net/usb/asix_devices.c
+++ b/drivers/net/usb/asix_devices.c
@@ -932,7 +932,8 @@ static int ax88772_stop(struct usbnet *dev)
 {
 	struct asix_common_private *priv = dev->driver_priv;
 
-	phylink_stop(priv->phylink);
+	if (!dev->suspend_count)
+		phylink_stop(priv->phylink);
 
 	return 0;
 }
-- 
2.34.1