netdev - Re: [PATCH] usbnet: ignore get interface retval of -EINPROGRESS

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Date:	Sat, 3 Sep 2011 12:32:44 -0500
From:	Jim Wylder <jwylder1@...orola.com>
To:	Oliver Neukum <oliver@...kum.org>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH] usbnet: ignore get interface retval of -EINPROGRESS

Oliver,

Thanks for the quick feedback.  True usbnet_start_xmit() could be
running at anytime, but the usb_autopm_get_interface_async() will only
return -EINPROGRESS when rpm_resume detects that
dev->power.runtime_status == RPM_RESUMING.  My understanding is that
for an asynchronous request, the promise that the device is resuming
would be equivalent to cases where usb_autopm_get_interface_async()
returns success.

In all other cases, when we are not attempting to resume an already
resuming interface, this change should have no impact.

Are you recommending that I add an additional check for DEV_ASLEEP,
possibly to decide whether to drop the or continue on?  Or am I
missing your point?  I had not done anything similar because my
understanding was that knowing that the device is in fact resuming
would be sufficient.

Jim

On Sat, Sep 3, 2011 at 11:37 AM, Oliver Neukum <oliver@...kum.org> wrote:
> Am Samstag, 3. September 2011, 16:21:00 schrieb Jim Wylder:
>> When calling pm_runtime_get, usb_autopm_get_interface_async
>> treats a return value of -EINPROGRESS as a success and
>> increments the usage count.  Since the interface is resuming,
>> it is safe for usbnet_start_xmit to submit the urb.
>
> usbnet_start_xmit() is exported, so simply stating that it is
> called when the interface is resumingisn't enough. It seems to
> me that the later check for DEV_ASLEEP will save as, but have
> you checked for that?
>
>        Regards
>                Oliver
>
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