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

Alan Stern
2009-12-07T15:51:21Z

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.

Alan Stern

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;
}