linux-kernel - Re: [PATCH] PM: Prevent waiting forever on asynchronous suspend after abort

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Date:	Thu, 21 Jun 2012 22:43:28 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	mandeep.baines@...il.com
Cc:	linux-kernel@...r.kernel.org,
	Mandeep Singh Baines <msb@...omium.org>,
	linux-pm@...r.kernel.org, stable@...nel.org,
	Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
	Kevin Hilman <khilman@...com>,
	Alan Stern <stern@...land.harvard.edu>,
	Colin Cross <ccross@...roid.com>,
	Sameer Nanda <snanda@...omium.org>,
	Olof Johansson <olofj@...omium.org>
Subject: Re: [PATCH] PM: Prevent waiting forever on asynchronous suspend after abort

On Wednesday, June 20, 2012, mandeep.baines@...il.com wrote:
> From: Mandeep Singh Baines <msb@...omium.org>
> 
> __device_suspend() must always send a completion. Otherwise, parent
> devices will wait forever.
> 
> Commit 1e2ef05b, "PM: Limit race conditions between runtime PM and
> system sleep (v2)", introduced a regression by short-circuiting the
> complete_all() for certain error cases.
> 
> This patch fixes the bug by always signalling a completion.
> 
> Addresses http://crosbug.com/31972
> 
> Tested by injecting an abort.
> 
> Signed-off-by: Mandeep Singh Baines <msb@...omium.org>
> Cc: Rafael J. Wysocki <rjw@...k.pl>
> Cc: linux-pm@...r.kernel.org
> Cc: stable@...nel.org
> Cc: Pavel Machek <pavel@....cz>
> Cc: Len Brown <len.brown@...el.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Kevin Hilman <khilman@...com>
> Cc: Alan Stern <stern@...land.harvard.edu>
> Cc: Colin Cross <ccross@...roid.com>
> Cc: Sameer Nanda <snanda@...omium.org>
> Cc: Olof Johansson <olofj@...omium.org>

Applied to linux-pm/linux-next, will be pushed to Linus in a couple of days.

Thanks,
Rafael


> ---
>  drivers/base/power/main.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index e0fb5b0..9cb845e 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -1031,7 +1031,7 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
>  	dpm_wait_for_children(dev, async);
>  
>  	if (async_error)
> -		return 0;
> +		goto Complete;
>  
>  	pm_runtime_get_noresume(dev);
>  	if (pm_runtime_barrier(dev) && device_may_wakeup(dev))
> @@ -1040,7 +1040,7 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
>  	if (pm_wakeup_pending()) {
>  		pm_runtime_put_sync(dev);
>  		async_error = -EBUSY;
> -		return 0;
> +		goto Complete;
>  	}
>  
>  	device_lock(dev);
> @@ -1097,6 +1097,8 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
>  	}
>  
>  	device_unlock(dev);
> +
> + Complete:
>  	complete_all(&dev->power.completion);
>  
>  	if (error) {
> 

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