PCI: Consolidate pci_bus/slot_lock/unlock/trylock()

pci_bus/slot_lock/unlock/trylock() largely duplicate the bus iteration loop
with variation only due to slot filter handling. The only differences in
the loops is where the struct bus is found (directly in the argument vs in
slot->bus) and whether slot filter is applied. Those differences are simple
to handle using function parameters.

Consolidate the bus iteration loop to one place by creating
__pci_bus_{lock,unlock,trylock}() and call them from the non-underscore
locking functions.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20260304122139.1479-1-ilpo.jarvinen@linux.intel.com

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 5984ad9ef6c46eaf93d09dcff69100780f95e838..0090b4034ec6d44d1984e6143feb369cd9166993 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5292,13 +5292,21 @@ static bool pci_bus_resettable(struct pci_bus *bus)
        return true;
 }
 
+static void pci_bus_lock(struct pci_bus *bus);
+static void pci_bus_unlock(struct pci_bus *bus);
+static int pci_bus_trylock(struct pci_bus *bus);
+
 /* Lock devices from the top of the tree down */
-static void pci_bus_lock(struct pci_bus *bus)
+static void __pci_bus_lock(struct pci_bus *bus, struct pci_slot *slot)
 {
-       struct pci_dev *dev;
+       struct pci_dev *dev, *bridge = bus->self;
+
+       if (bridge)
+               pci_dev_lock(bridge);
 
-       pci_dev_lock(bus->self);
        list_for_each_entry(dev, &bus->devices, bus_list) {
+               if (slot && (!dev->slot || dev->slot != slot))
+                       continue;
                if (dev->subordinate)
                        pci_bus_lock(dev->subordinate);
                else
@@ -5307,28 +5315,34 @@ static void pci_bus_lock(struct pci_bus *bus)
 }
 
 /* Unlock devices from the bottom of the tree up */
-static void pci_bus_unlock(struct pci_bus *bus)
+static void __pci_bus_unlock(struct pci_bus *bus, struct pci_slot *slot)
 {
-       struct pci_dev *dev;
+       struct pci_dev *dev, *bridge = bus->self;
 
        list_for_each_entry(dev, &bus->devices, bus_list) {
+               if (slot && (!dev->slot || dev->slot != slot))
+                       continue;
                if (dev->subordinate)
                        pci_bus_unlock(dev->subordinate);
                else
                        pci_dev_unlock(dev);
        }
-       pci_dev_unlock(bus->self);
+
+       if (bridge)
+               pci_dev_unlock(bridge);
 }
 
 /* Return 1 on successful lock, 0 on contention */
-static int pci_bus_trylock(struct pci_bus *bus)
+static int __pci_bus_trylock(struct pci_bus *bus, struct pci_slot *slot)
 {
-       struct pci_dev *dev;
+       struct pci_dev *dev, *bridge = bus->self;
 
-       if (!pci_dev_trylock(bus->self))
+       if (bridge && !pci_dev_trylock(bridge))
                return 0;
 
        list_for_each_entry(dev, &bus->devices, bus_list) {
+               if (slot && (!dev->slot || dev->slot != slot))
+                       continue;
                if (dev->subordinate) {
                        if (!pci_bus_trylock(dev->subordinate))
                                goto unlock;
@@ -5339,15 +5353,37 @@ static int pci_bus_trylock(struct pci_bus *bus)
 
 unlock:
        list_for_each_entry_continue_reverse(dev, &bus->devices, bus_list) {
+               if (slot && (!dev->slot || dev->slot != slot))
+                       continue;
                if (dev->subordinate)
                        pci_bus_unlock(dev->subordinate);
                else
                        pci_dev_unlock(dev);
        }
-       pci_dev_unlock(bus->self);
+
+       if (bridge)
+               pci_dev_unlock(bridge);
        return 0;
 }
 
+/* Lock devices from the top of the tree down */
+static void pci_bus_lock(struct pci_bus *bus)
+{
+       __pci_bus_lock(bus, NULL);
+}
+
+/* Unlock devices from the bottom of the tree up */
+static void pci_bus_unlock(struct pci_bus *bus)
+{
+       __pci_bus_unlock(bus, NULL);
+}
+
+/* Return 1 on successful lock, 0 on contention */
+static int pci_bus_trylock(struct pci_bus *bus)
+{
+       return __pci_bus_trylock(bus, NULL);
+}
+
 /* Do any devices on or below this slot prevent a bus reset? */
 static bool pci_slot_resettable(struct pci_slot *slot)
 {
@@ -5370,72 +5406,19 @@ 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, *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)
-                       continue;
-               if (dev->subordinate)
-                       pci_bus_lock(dev->subordinate);
-               else
-                       pci_dev_lock(dev);
-       }
+       __pci_bus_lock(slot->bus, slot);
 }
 
 /* Unlock devices from the bottom of the tree up */
 static void pci_slot_unlock(struct pci_slot *slot)
 {
-       struct pci_dev *dev, *bridge = slot->bus->self;
-
-       list_for_each_entry(dev, &slot->bus->devices, bus_list) {
-               if (!dev->slot || dev->slot != slot)
-                       continue;
-               if (dev->subordinate)
-                       pci_bus_unlock(dev->subordinate);
-               else
-                       pci_dev_unlock(dev);
-       }
-
-       if (bridge)
-               pci_dev_unlock(bridge);
+       __pci_bus_unlock(slot->bus, slot);
 }
 
 /* Return 1 on successful lock, 0 on contention */
 static int pci_slot_trylock(struct pci_slot *slot)
 {
-       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)
-                       continue;
-               if (dev->subordinate) {
-                       if (!pci_bus_trylock(dev->subordinate))
-                               goto unlock;
-               } else if (!pci_dev_trylock(dev))
-                       goto unlock;
-       }
-       return 1;
-
-unlock:
-       list_for_each_entry_continue_reverse(dev,
-                                            &slot->bus->devices, bus_list) {
-               if (!dev->slot || dev->slot != slot)
-                       continue;
-               if (dev->subordinate)
-                       pci_bus_unlock(dev->subordinate);
-               else
-                       pci_dev_unlock(dev);
-       }
-
-       if (bridge)
-               pci_dev_unlock(bridge);
-       return 0;
+       return __pci_bus_trylock(slot->bus, slot);
 }
 
 /*