Commit a5f76d5e authored Jun 21, 2011 by Rafael J. Wysocki

PCI / PM: Block races between runtime PM and system sleep



After commit e8665002
(PM: Allow pm_runtime_suspend() to succeed during system suspend) it
is possible that a device resumed by the pm_runtime_resume(dev) in
pci_pm_prepare() will be suspended immediately from a work item,
timer function or otherwise, defeating the very purpose of calling
pm_runtime_resume(dev) from there.  To prevent that from happening
it is necessary to increment the runtime PM usage counter of the
device by replacing pm_runtime_resume() with pm_runtime_get_sync().
Moreover, the incremented runtime PM usage counter has to be
decremented by the corresponding pci_pm_complete(), via
pm_runtime_put_sync().

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: stable@kernel.org
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>

parent ca9c6890

drivers/pci/pci-driver.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -624,7 +624,7 @@ static int pci_pm_prepare(struct device *dev)
		* system from the sleep state, we'll have to prevent it from signaling
		* wake-up.
		*/
		pm_runtime_resume(dev);
		pm_runtime_get_sync(dev);

		if (drv && drv->pm && drv->pm->prepare)
		error = drv->pm->prepare(dev);
		@@ -638,6 +638,8 @@ static void pci_pm_complete(struct device *dev)

		if (drv && drv->pm && drv->pm->complete)
		drv->pm->complete(dev);

		pm_runtime_put_sync(dev);
		}

		#else /* !CONFIG_PM_SLEEP */

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