[PATCHv2 2/4] pci: fix slot reset device locking

[Keith Busch <kbusch@meta.com>]

From: Keith Busch <kbusch@kernel.org>

Like pci_bus_lock, pci_slot_lock needs to lock the bridge device to
prevent warnings like:

  pcieport 0000:e2:05.0: unlocked secondary bus reset via: pciehp_reset_slot+0x55/0xa0

Take and release the lock for the bridge providing the slot for the
lock/trylock and unlock routines.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/pci/pci.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 59319e08fca61..57a5b205175f1 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5290,10 +5290,9 @@ static int pci_bus_trylock(struct pci_bus *bus)
 /* Do any devices on or below this slot prevent a bus reset? */
 static bool pci_slot_resettable(struct pci_slot *slot)
 {
-	struct pci_dev *dev;
+	struct pci_dev *dev, *bridge = slot->bus->self;
 
-	if (slot->bus->self &&
-	    (slot->bus->self->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET))
+	if (bridge && (bridge->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET))
 		return false;
 
 	list_for_each_entry(dev, &slot->bus->devices, bus_list) {
@@ -5310,7 +5309,10 @@ static bool pci_slot_resettable(struct pci_slot *slot)
 /* Lock devices from the top of the tree down */
 static void pci_slot_lock(struct pci_slot *slot)
 {
-	struct pci_dev *dev;
+	struct pci_dev *dev, *bridge = slot->bus->self;
+
+	if (bridge)
+		pci_dev_lock(bridge);
 
 	list_for_each_entry(dev, &slot->bus->devices, bus_list) {
 		if (!dev->slot || dev->slot != slot)
@@ -5325,7 +5327,7 @@ static void pci_slot_lock(struct pci_slot *slot)
 /* Unlock devices from the bottom of the tree up */
 static void pci_slot_unlock(struct pci_slot *slot)
 {
-	struct pci_dev *dev;
+	struct pci_dev *dev, *bridge = slot->bus->self;
 
 	list_for_each_entry(dev, &slot->bus->devices, bus_list) {
 		if (!dev->slot || dev->slot != slot)
@@ -5335,12 +5337,18 @@ static void pci_slot_unlock(struct pci_slot *slot)
 		else
 			pci_dev_unlock(dev);
 	}
+
+	if (bridge)
+		pci_dev_unlock(bridge);
 }
 
 /* Return 1 on successful lock, 0 on contention */
 static int pci_slot_trylock(struct pci_slot *slot)
 {
-	struct pci_dev *dev;
+	struct pci_dev *dev, *bridge = slot->bus->self;
+
+	if (bridge && !pci_dev_trylock(bridge))
+		return 0;
 
 	list_for_each_entry(dev, &slot->bus->devices, bus_list) {
 		if (!dev->slot || dev->slot != slot)
@@ -5363,6 +5371,9 @@ static int pci_slot_trylock(struct pci_slot *slot)
 		else
 			pci_dev_unlock(dev);
 	}
+
+	if (bridge)
+		pci_dev_unlock(bridge);
 	return 0;
 }
 
-- 
2.47.3