linux-kernel - Re: [PATCH 4.4 18/31] r8152: napi hangup fix after disconnect

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Message-ID: <1535128726.2902.32.camel@codethink.co.uk>
Date:   Fri, 24 Aug 2018 17:38:46 +0100
From:   Ben Hutchings <ben.hutchings@...ethink.co.uk>
To:     Jiri Slaby <jslaby@...e.cz>, linux-usb@...r.kernel.org,
        netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>
Cc:     stable@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4.4 18/31] r8152: napi hangup fix after disconnect

On Fri, 2018-07-20 at 14:13 +0200, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Jiri Slaby <jslaby@...e.cz>
> 
> [ Upstream commit 0ee1f4734967af8321ecebaf9c74221ace34f2d5 ]
[...]
> --- a/drivers/net/usb/r8152.c
> +++ b/drivers/net/usb/r8152.c
> @@ -3139,7 +3139,8 @@ 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);

This flag appears to be set only if the USB device is actually
disconnected.  In case the driver is unbound for some other reason
(like the module is removed), the same problem will occur.

What I think might work is to do:

	if (!list_empty(&tp->napi.dev_list)
		napi_disable(&tp->napi);

Ben.

-- 
Ben Hutchings, Software Developer                         Codethink Ltd
https://www.codethink.co.uk/                 Dale House, 35 Dale Street
                                     Manchester, M1 2HF, United Kingdom