PCI PM: Restore standard config registers of all devices early

There is a problem in our handling of suspend-resume of PCI devices that
many of them have their standard config registers restored with
interrupts enabled and they are put into the full power state with
interrupts enabled as well.  This may lead to the following scenario:
  * an interrupt vector is shared between two or more devices
  * one device is resumed earlier and generates an interrupt
  * the interrupt handler of another device tries to handle it and
    attempts to access the device the config space of which hasn't been
    restored yet and/or which still is in a low power state
  * the system crashes as a result

To prevent this from happening we should restore the standard
configuration registers of all devices with interrupts disabled and we
should put them into the D0 power state right after that.
Unfortunately, this cannot be done using the existing
pci_set_power_state(), because it can sleep.  Also, to do it we have to
make sure that the config spaces of all devices were actually saved
during suspend.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 27 insertions, 64 deletions

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index c697f26..9de07b7 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -355,17 +355,27 @@ static int pci_legacy_suspend(struct device *dev, pm_message_t state)
 	int i = 0;
 
 	if (drv && drv->suspend) {
+		pci_dev->state_saved = false;
+
 		i = drv->suspend(pci_dev, state);
 		suspend_report_result(drv->suspend, i);
-	} else {
-		pci_save_state(pci_dev);
-		/*
-		 * This is for compatibility with existing code with legacy PM
-		 * support.
-		 */
-		pci_pm_set_unknown_state(pci_dev);
+		if (i)
+			return i;
+
+		if (pci_dev->state_saved)
+			goto Fixup;
+
+		if (WARN_ON_ONCE(pci_dev->current_state != PCI_D0))
+			goto Fixup;
 	}
 
+	pci_save_state(pci_dev);
+	/*
+	 * This is for compatibility with existing code with legacy PM support.
+	 */
+	pci_pm_set_unknown_state(pci_dev);
+
+ Fixup:
 	pci_fixup_device(pci_fixup_suspend, pci_dev);
 
 	return i;
@@ -386,81 +396,34 @@ static int pci_legacy_suspend_late(struct device *dev, pm_message_t state)
 
 static int pci_legacy_resume_early(struct device *dev)
 {
-	int error = 0;
 	struct pci_dev * pci_dev = to_pci_dev(dev);
 	struct pci_driver * drv = pci_dev->driver;
 
-	pci_fixup_device(pci_fixup_resume_early, pci_dev);
-
-	if (drv && drv->resume_early)
-		error = drv->resume_early(pci_dev);
-	return error;
+	return drv && drv->resume_early ?
+			drv->resume_early(pci_dev) : 0;
 }
 
 static int pci_legacy_resume(struct device *dev)
 {
-	int error;
 	struct pci_dev * pci_dev = to_pci_dev(dev);
 	struct pci_driver * drv = pci_dev->driver;
 
 	pci_fixup_device(pci_fixup_resume, pci_dev);
 
-	if (drv && drv->resume) {
-		error = drv->resume(pci_dev);
-	} else {
-		/* restore the PCI config space */
-		pci_restore_state(pci_dev);
-		error = pci_pm_reenable_device(pci_dev);
-	}
-	return error;
+	return drv && drv->resume ?
+			drv->resume(pci_dev) : pci_pm_reenable_device(pci_dev);
 }
 
 /* Auxiliary functions used by the new power management framework */
 
-static int pci_restore_standard_config(struct pci_dev *pci_dev)
-{
-	struct pci_dev *parent = pci_dev->bus->self;
-	int error = 0;
-
-	/* Check if the device's bus is operational */
-	if (!parent || parent->current_state == PCI_D0) {
-		pci_restore_state(pci_dev);
-		pci_update_current_state(pci_dev, PCI_D0);
-	} else {
-		dev_warn(&pci_dev->dev, "unable to restore config, "
-			"bridge %s in low power state D%d\n", pci_name(parent),
-			parent->current_state);
-		pci_dev->current_state = PCI_UNKNOWN;
-		error = -EAGAIN;
-	}
-
-	return error;
-}
-
-static bool pci_is_bridge(struct pci_dev *pci_dev)
-{
-	return !!(pci_dev->subordinate);
-}
-
 static void pci_pm_default_resume_noirq(struct pci_dev *pci_dev)
 {
-	if (pci_restore_standard_config(pci_dev))
-		pci_fixup_device(pci_fixup_resume_early, pci_dev);
+	pci_restore_standard_config(pci_dev);
+	pci_fixup_device(pci_fixup_resume_early, pci_dev);
 }
 
 static int pci_pm_default_resume(struct pci_dev *pci_dev)
 {
-	/*
-	 * pci_restore_standard_config() should have been called once already,
-	 * but it would have failed if the device's parent bridge had not been
-	 * in power state D0 at that time.  Check it and try again if necessary.
-	 */
-	if (pci_dev->current_state == PCI_UNKNOWN) {
-		int error = pci_restore_standard_config(pci_dev);
-		if (error)
-			return error;
-	}
-
 	pci_fixup_device(pci_fixup_resume, pci_dev);
 
 	if (!pci_is_bridge(pci_dev))
@@ -575,11 +538,11 @@ static int pci_pm_resume_noirq(struct device *dev)
 	struct device_driver *drv = dev->driver;
 	int error = 0;
 
+	pci_pm_default_resume_noirq(pci_dev);
+
 	if (pci_has_legacy_pm_support(pci_dev))
 		return pci_legacy_resume_early(dev);
 
-	pci_pm_default_resume_noirq(pci_dev);
-
 	if (drv && drv->pm && drv->pm->resume_noirq)
 		error = drv->pm->resume_noirq(dev);
 
@@ -730,11 +693,11 @@ static int pci_pm_restore_noirq(struct device *dev)
 	struct device_driver *drv = dev->driver;
 	int error = 0;
 
+	pci_pm_default_resume_noirq(pci_dev);
+
 	if (pci_has_legacy_pm_support(pci_dev))
 		return pci_legacy_resume_early(dev);
 
-	pci_pm_default_resume_noirq(pci_dev);
-
 	if (drv && drv->pm && drv->pm->restore_noirq)
 		error = drv->pm->restore_noirq(dev);