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

Rafael J. Wysocki
2009-12-07T20:26:49Z

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;
> }
>
>
>