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r8152: napi hangup fix after disconnect 

When unplugging an r8152 adapter while the interface is UP, the NIC
becomes unusable.  usb->disconnect (aka rtl8152_disconnect) deletes
napi. Then, rtl8152_disconnect calls unregister_netdev and that invokes
netdev->ndo_stop (aka rtl8152_close). rtl8152_close tries to
napi_disable, but the napi is already deleted by disconnect above. So
the first while loop in napi_disable never finishes. This results in
complete deadlock of the network layer as there is rtnl_mutex held by
unregister_netdev.

So avoid the call to napi_disable in rtl8152_close when the device is
already gone.

The other calls to usb_kill_urb, cancel_delayed_work_sync,
netif_stop_queue etc. seem to be fine. The urb and netdev is not
destroyed yet.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: linux-usb@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jiri Slaby 2018-06-25 09:26:27 +02:00 committed by David S. Miller
parent 6f0d349d92
commit 0ee1f47349
1 changed files with 2 additions and 1 deletions
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3
drivers/net/usb/r8152.c
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@ -3962,7 +3962,8 @@ static int rtl8152_close(struct net_device *netdev)
#ifdef CONFIG_PM_SLEEP
unregister_pm_notifier(&tp->pm_notifier);
#endif
napi_disable(&tp->napi);
if (!test_bit(RTL8152_UNPLUG, &tp->flags))
napi_disable(&tp->napi);
clear_bit(WORK_ENABLE, &tp->flags);
usb_kill_urb(tp->intr_urb);
cancel_delayed_work_sync(&tp->schedule);