[PATCH 6.19 333/844] PCI: Fix pci_slot_lock () device locking

[Sasha Levin]

From: Keith Busch <kbusch@xxxxxxxxxx>

[ Upstream commit 1f5e57c622b4dc9b8e7d291d560138d92cfbe5bf ]

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.

Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Link: https://patch.msgid.link/20260130165953.751063-3-kbusch@xxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 a05978f5cf2c7..41596bc72f1dc 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5293,10 +5293,9 @@ 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) {
@@ -5313,7 +5312,10 @@ 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)
@@ -5328,7 +5330,7 @@ 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)
@@ -5338,12 +5340,18 @@ 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)
@@ -5368,6 +5376,9 @@ static int pci_slot_trylock(struct pci_slot *slot)
 		else
 			pci_dev_unlock(dev);
 	}
+
+	if (bridge)
+		pci_dev_unlock(bridge);
 	return 0;
 }
 
-- 
2.51.0