netdev - Re: [PATCH net] net: qmi_wwan: fix Oops while disconnecting

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Message-ID: <CACVXFVNmquD6nhcJkumZsnXH7T+Ga3YNt9EAQ=-5HUkYwEdp7w@mail.gmail.com>
Date:	Sat, 23 Jun 2012 11:32:32 +0800
From:	Ming Lei <tom.leiming@...il.com>
To:	Bjørn Mork <bjorn@...k.no>
Cc:	netdev@...r.kernel.org, linux-usb@...r.kernel.org,
	Marius Bjørnstad Kotsbak 
	<marius.kotsbak@...il.com>
Subject: Re: [PATCH net] net: qmi_wwan: fix Oops while disconnecting

On Fri, Jun 22, 2012 at 5:11 PM, Bjørn Mork <bjorn@...k.no> wrote:

>
> Reported-by: Marius Bjørnstad Kotsbak <marius.kotsbak@...il.com>
> Cc: <stable@...r.kernel.org> # v3.4
> Signed-off-by: Bjørn Mork <bjorn@...k.no>
> ---
>  drivers/net/usb/qmi_wwan.c |    4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
> index 3767a12..b01960f 100644
> --- a/drivers/net/usb/qmi_wwan.c
> +++ b/drivers/net/usb/qmi_wwan.c
> @@ -197,6 +197,10 @@ err:
>  static int qmi_wwan_cdc_wdm_manage_power(struct usb_interface *intf, int on)
>  {
>        struct usbnet *dev = usb_get_intfdata(intf);
> +
> +       /* can be called while disconnecting */
> +       if (!dev)
> +               return 0;
>        return qmi_wwan_manage_power(dev, on);
>  }

Considered there isn't any protection between usbnet_disconnet and
wdm_open/wdm_close, you patch still doesn't work on the race, see
below:

   +       if (!dev)
   +               return 0;

            -> usbnet_disconnect() triggered and completed, so


            return qmi_wwan_manage_power(dev, on);




Thanks,
-- 
Ming Lei
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