linux-kernel - Re: [PATCH 2/2] PM/runtime: handle ->runtime

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Date:	Sun, 11 Sep 2011 16:44:31 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Ming Lei <tom.leiming@...il.com>
cc:	rjw@...k.pl, <linux-pm@...ts.linux-foundation.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] PM/runtime: handle ->runtime_suspend failure correctly

On Sat, 10 Sep 2011 tom.leiming@...il.com wrote:

> From: Ming Lei <tom.leiming@...il.com>
> 
> If ->runtime_suspend returns -EAGAIN or -EBUSY, the device should
> still be in ACTIVE state, so it is not needed to handle defered
> resume and idle notification to its parent; if ->runtime_suspend
> returns other fatal failure, it doesn't make sense to process defered
> resume and send idle notification to its parent.

> @@ -422,6 +425,9 @@ static int rpm_suspend(struct device *dev, int rpmflags)
>  	}
>  	wake_up_all(&dev->power.wait_queue);
>  
> +	if (retval)
> +		goto out;
> +
>  	if (dev->power.deferred_resume) {
>  		rpm_resume(dev, 0);
>  		retval = -EAGAIN;

If there's a suspend failure, the deferred_resume flag gets turned off 
anyway.  But skipping this test won't hurt, and skipping the parent 
notification is a good idea.

In fact, it might be even better to put a copy of the wake_up_all() in
the "if (retval)" branch after the suspend callback and then go
directly to out.  The "else" branch could then become part of the
straight-through code, not indented.

Alan Stern

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