netdev - Re: [PATCH 1/1] r8152: napi hangup fix after disconnect

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Date:   Tue, 26 Jun 2018 18:01:34 +0900 (KST)
From:   David Miller <davem@...emloft.net>
To:     jslaby@...e.cz
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH 1/1] r8152: napi hangup fix after disconnect

From: Jiri Slaby <jslaby@...e.cz>
Date: Mon, 25 Jun 2018 09:26:27 +0200

> 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@...e.cz>

Applied, thank you.