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

After commit e866500247
(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>
This commit is contained in:
Rafael J. Wysocki 2011-06-21 23:47:15 +02:00
parent ca9c6890b5
commit a5f76d5eba
1 changed files with 3 additions and 1 deletions
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4
drivers/pci/pci-driver.c
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@ -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 * system from the sleep state, we'll have to prevent it from signaling
* wake-up. * wake-up.
*/ */
pm_runtime_resume(dev); pm_runtime_get_sync(dev);
if (drv && drv->pm && drv->pm->prepare) if (drv && drv->pm && drv->pm->prepare)
error = drv->pm->prepare(dev); error = drv->pm->prepare(dev);
@ -638,6 +638,8 @@ static void pci_pm_complete(struct device *dev)
if (drv && drv->pm && drv->pm->complete) if (drv && drv->pm && drv->pm->complete)
drv->pm->complete(dev); drv->pm->complete(dev);
pm_runtime_put_sync(dev);
} }
#else /* !CONFIG_PM_SLEEP */ #else /* !CONFIG_PM_SLEEP */