Re: [PATCH ver. 3] PM: allow for usage_count > 0 in pm_runtime_get()

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Monday 07 December 2009, Alan Stern wrote:
> This patch (as1308c) fixes __pm_runtime_get().  Currently the routine
> will resume a device if the prior usage count was 0.  But this isn't
> right; thanks to pm_runtime_get_noresume() the usage count can be
> positive even while the device is suspended.
> 
> Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
> 
> ---
> 
> Rafael:
> 
> This patch contains the most important part of the patch you rejected
> last week, leaving out the semantic changes you didn't like.  It really
> does fix a bug, and it should be sent to Linus before the merge window
> closes.

Thanks, I'll include it into the next pull request.

Rafael


> Index: usb-2.6/drivers/base/power/runtime.c
> ===================================================================
> --- usb-2.6.orig/drivers/base/power/runtime.c
> +++ usb-2.6/drivers/base/power/runtime.c
> @@ -699,15 +699,15 @@ EXPORT_SYMBOL_GPL(pm_request_resume);
>   * @dev: Device to handle.
>   * @sync: If set and the device is suspended, resume it synchronously.
>   *
> - * Increment the usage count of the device and if it was zero previously,
> - * resume it or submit a resume request for it, depending on the value of @sync.
> + * Increment the usage count of the device and resume it or submit a resume
> + * request for it, depending on the value of @sync.
>   */
>  int __pm_runtime_get(struct device *dev, bool sync)
>  {
> -	int retval = 1;
> +	int retval;
>  
> -	if (atomic_add_return(1, &dev->power.usage_count) == 1)
> -		retval = sync ? pm_runtime_resume(dev) : pm_request_resume(dev);
> +	atomic_inc(&dev->power.usage_count);
> +	retval = sync ? pm_runtime_resume(dev) : pm_request_resume(dev);
>  
>  	return retval;
>  }
> 
> 
>