netdev - Re: [PATCHv5] usbnet: Resubmit interrupt URB once if halted

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Message-ID: <BANLkTim1Np+RT-js-HPFvBA5yM=EFoPs6w@mail.gmail.com>
Date:	Mon, 25 Apr 2011 11:41:29 -0700
From:	Paul Stewart <pstew@...omium.org>
To:	Oliver Neukum <oliver@...kum.org>
Cc:	Alan Stern <stern@...land.harvard.edu>, netdev@...r.kernel.org,
	linux-usb@...r.kernel.org, davem@...emloft.net,
	bhutchings@...arflare.com
Subject: Re: [PATCHv5] usbnet: Resubmit interrupt URB once if halted

On Sat, Apr 23, 2011 at 11:36 PM, Oliver Neukum <oliver@...kum.org> wrote:
> Am Freitag, 22. April 2011, 17:59:15 schrieb Paul Stewart:
>> >
>> >>       free_netdev(net);
>> >>       usb_put_dev (xdev);
>> >>  }
>> >> @@ -1285,6 +1291,10 @@ int usbnet_suspend (struct usb_interface *intf, pm_message_t message)
>> >>                * wake the device
>> >>                */
>> >>               netif_device_attach (dev->net);
>> >> +
>> >> +             /* Stop interrupt URBs */
>> >> +             if (dev->interrupt)
>> >> +                     usb_kill_urb(dev->interrupt);
>> >>       }
>> >>       return 0;
>> >>  }
>> >
>> > There is a subtle question here: When is the best time to kill the
>> > interrupt URB?  Without knowing any of the details, I'd guess that the
>> > interrupt URB reports asynchronous events and the driver could run into
>> > trouble if one of those events occurred while everything else was
>> > turned off.  This suggests that the interrupt URB should be killed as
>> > soon as possible rather than as late as possible.  But maybe it doesn't
>> > matter; it all depends on the design of the driver.
>>
>> I'm not sure I can answer this question either.  As it stands, nobody
>> was killing them before.  Just trying to make it better.
>
> Hm. Are we looking at the same code?

Perhaps not.  I'm working out of the netdev-2.6 git repository.  Is
this the wrong place?

> usbnet_suspend now has:
>
>                /*
>                 * accelerate emptying of the rx and queues, to avoid
>                 * having everything error out.
>                 */
>                netif_device_detach (dev->net);
>                usbnet_terminate_urbs(dev);
>                usb_kill_urb(dev->interrupt);
>
> This suggests that if you want to resubmit the interrupt URB in resume()
> you do it first. Which drivers use the interrupt URB?

The asix driver uses it fo signal link status.

>
>        Regards
>                Oliver
>
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