netdev - another race in hso

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Message-Id: <200812191145.31556.oliver@neukum.org>
Date:	Fri, 19 Dec 2008 11:45:30 +0100
From:	Oliver Neukum <oliver@...kum.org>
To:	ajb@...eresystems.co.uk, "Greg Kroah-Hartman" <greg@...ah.com>,
	Denis Joseph Barrow <D.Barow@...ion.com>,
	linux-usb@...r.kernel.org, netdev@...r.kernel.org
Subject: another race in hso

Hi,

there is another race.

static int hso_get_activity(struct hso_device *hso_dev)
{
	if (hso_dev->usb->state == USB_STATE_SUSPENDED) {
		if (!hso_dev->is_active) {
			hso_dev->is_active = 1;
			schedule_work(&hso_dev->async_get_intf);
		}
	}

	if (hso_dev->usb->state != USB_STATE_CONFIGURED)
		return -EAGAIN;

here's the window.

	usb_mark_last_busy(hso_dev->usb);

	return 0;
}

CPU A							CPU B

run until the window
								autosuspend of device
submitting URB to suspended device

You get an unnecessary error.

	Regards
		Oliver
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