linux-kernel - Re: [PATCH net] r8152: use cancel_delayed

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Date:	Sat, 18 Oct 2014 21:48:19 +0200
From:	Oliver Neukum <oliver@...kum.org>
To:	Hayes Wang <hayeswang@...ltek.com>
Cc:	netdev@...r.kernel.org, nic_swsd@...ltek.com,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH net] r8152: use cancel_delayed_work for runtime suspend

On Fri, 2014-10-17 at 13:55 +0800, Hayes Wang wrote:
> It would cause dead lock for runtime suspend, when the workqueue
> is running and runtime suspend occurs before the workqueue wakes
> up the device. The rtl8152_suspend() waits the workqueue to finish
> because of calling cancel_delayed_work_sync(). The workqueue waits
> the suspend function to finish for waking up the device because of
> calling usb_autopm_get_interface().

The diagnosis is good, the fix is not good. It opens a race
during which the queued work can touch a suspended device.

	Regards
		Oliver


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