linux-kernel - Re: [PATCH net] cdc_ether: Fix handling connection notification

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Message-ID: <CAKfDRXjfHWyrFbWjffdWBZj2KXb+bnoDu9oHrcU40=XWe7fBjw@mail.gmail.com>
Date:   Wed, 30 Nov 2016 22:59:32 +0100
From:   Kristian Evensen <kristian.evensen@...il.com>
To:     Bjørn Mork <bjorn@...k.no>
Cc:     Oliver Neukum <oliver@...kum.org>, linux-usb@...r.kernel.org,
        Network Development <netdev@...r.kernel.org>,
        linux-kernel@...r.kernel.org,
        Henning Schild <henning.schild@...mens.com>
Subject: Re: [PATCH net] cdc_ether: Fix handling connection notification

On Wed, Nov 30, 2016 at 10:51 PM, Bjørn Mork <bjorn@...k.no> wrote:
> Kristian Evensen <kristian.evensen@...il.com> writes:
>
>> +void usbnet_cdc_zte_status(struct usbnet *dev, struct urb *urb)
>> +{
>> +     struct usb_cdc_notification *event;
>> +
>> +     if (urb->actual_length < sizeof(*event))
>> +             return;
>> +
>> +     event = urb->transfer_buffer;
>> +
>> +     if (event->bNotificationType != USB_CDC_NOTIFY_NETWORK_CONNECTION) {
>> +             usbnet_cdc_status(dev, urb);
>> +             return;
>> +     }
>> +
>> +     netif_dbg(dev, timer, dev->net, "CDC: carrier %s\n",
>> +               event->wValue ? "on" : "off");
>> +
>> +     if (event->wValue &&
>> +         !test_bit(__LINK_STATE_NOCARRIER, &dev->net->state))
>> +             usbnet_link_change(dev, 0, 0);
>> +
>> +     usbnet_link_change(dev, !!event->wValue, 0);
>> +}
>
> As Henning said: Use netif_carrier_ok instead of open coding it.
>
> But I also think you need to replace the first usbnet_link_change() with
> a plain netif_carrier_off(dev->net).  Calling usbnet_link_change() twice
> here is only going to set off the "kevent XX may have been dropped"
> message since you call schedule_work() twice without giving the work
> queue a chance to be processed.  No need to do that.

Thanks for the feedback and agree. Will submit a v2 tomorrow.

-Kristian