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    Subject[PATCH 4.14 42/92] r8152: napi hangup fix after disconnect
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jiri Slaby <jslaby@suse.cz>

    [ Upstream commit 0ee1f4734967af8321ecebaf9c74221ace34f2d5 ]

    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>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/net/usb/r8152.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/drivers/net/usb/r8152.c
    +++ b/drivers/net/usb/r8152.c
    @@ -3959,7 +3959,8 @@ static int rtl8152_close(struct net_devi
    #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);

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