netdev - Re: [PATCHv4] usbnet: Resubmit interrupt URB once if halted

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Message-ID: <Pine.LNX.4.44L0.1104211737510.1939-100000@iolanthe.rowland.org>
Date:	Thu, 21 Apr 2011 17:40:54 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Oliver Neukum <oliver@...kum.org>
cc:	Paul Stewart <pstew@...omium.org>, <netdev@...r.kernel.org>,
	<linux-usb@...r.kernel.org>, <davem@...emloft.net>,
	<greg@...ah.com>
Subject: Re: [PATCHv4] usbnet: Resubmit interrupt URB once if halted

On Thu, 21 Apr 2011, Oliver Neukum wrote:

> Am Donnerstag, 21. April 2011, 16:03:34 schrieb Alan Stern:
> > On Tue, 19 Apr 2011, Paul Stewart wrote:
> 
> > > This version of the patch moves the urb submit directly into
> > > usbnet_resume.  Is it okay to submit a GFP_KERNEL urb from
> > > usbnet_resume()?
> 
> Suppose a device of two interfaces one of them storage is autosuspended.
> GFP_KERNEL in the first device to be resumed triggers a pageout to the
> suspended storage device.

True enough, I had forgotten about that.  A resume routine should 
always use GFP_NOIO, not GFP_KERNEL.

In fact this restriction is true in general, not just for USB devices 
containing a mass-storage interface.  The backing device for an evicted 
page might not be resumed until later on in the resume sequence.

Alan Stern

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