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PCI: Introduce PCI_SLOT_PLACEHOLDER constant for slot_nr placeholder value

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Introduce a constant for placeholder value and update the kerneldoc for
pci_create_slot() to reference PCI_SLOT_PLACEHOLDER instead of -1
throughout. No functional change.

Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Tyrel Datwyler <tyreld@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://patch.msgid.link/20260805165518.794-2-alifm@linux.ibm.com
This commit is contained in:
Farhan Ali 2026-08-05 09:55:14 -07:00 committed by Bjorn Helgaas
parent dc59e4fea9
commit c243e6c470
4 changed files with 16 additions and 12 deletions
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2
drivers/pci/hotplug/pnv_php.c
View File

@ -808,7 +808,7 @@ static struct pnv_php_slot *pnv_php_alloc_slot(struct device_node *dn)
if (dn->child && PCI_DN(dn->child))
php_slot->slot_no = PCI_SLOT(PCI_DN(dn->child)->devfn);
else
php_slot->slot_no = -1; /* Placeholder slot */
php_slot->slot_no = PCI_SLOT_PLACEHOLDER; /* Placeholder slot */
kref_init(&php_slot->kref);
php_slot->state = PNV_PHP_STATE_INITIALIZED;

2
drivers/pci/hotplug/rpaphp_slot.c
View File

@ -84,7 +84,7 @@ int rpaphp_register_slot(struct slot *slot)
struct hotplug_slot *php_slot = &slot->hotplug_slot;
u32 my_index;
int retval;
int slotno = -1;
int slotno = PCI_SLOT_PLACEHOLDER;
dbg("%s registering slot:path[%pOF] index[%x], name[%s] pdomain[%x] type[%d]\n",
__func__, slot->dn, slot->index, slot->name,

21
drivers/pci/slot.c
View File

@ -37,7 +37,7 @@ static const struct sysfs_ops pci_slot_sysfs_ops = {
static ssize_t address_read_file(struct pci_slot *slot, char *buf)
{
if (slot->number == 0xff)
if (slot->number == PCI_SLOT_PLACEHOLDER)
return sysfs_emit(buf, "%04x:%02x\n",
pci_domain_nr(slot->bus),
slot->bus->number);
@ -210,7 +210,7 @@ static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
/**
* pci_create_slot - create or increment refcount for physical PCI slot
* @parent: struct pci_bus of parent bridge
* @slot_nr: PCI_SLOT(pci_dev->devfn), -1 for placeholder, or
* @slot_nr: PCI_SLOT(pci_dev->devfn), PCI_SLOT_PLACEHOLDER for placeholder, or
* PCI_SLOT_ALL_DEVICES
* @name: user visible string presented in /sys/bus/pci/slots/<name>
* @hotplug: set if caller is hotplug driver, NULL otherwise
@ -236,15 +236,16 @@ static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
* In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
* a slot. There is one notable exception - pSeries (rpaphp), where the
* @slot_nr cannot be determined until a device is actually inserted into
* the slot. In this scenario, the caller may pass -1 for @slot_nr.
* the slot. In this scenario, the caller may pass PCI_SLOT_PLACEHOLDER for @slot_nr.
*
* The following semantics are imposed when the caller passes @slot_nr ==
* -1. First, we no longer check for an existing %struct pci_slot, as there
* may be many slots with @slot_nr of -1. The other change in semantics is
* user-visible, which is the 'address' parameter presented in sysfs will
* consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
* %struct pci_bus and bb is the bus number. In other words, the devfn of
* the 'placeholder' slot will not be displayed.
* PCI_SLOT_PLACEHOLDER. First, we no longer check for an existing %struct
* pci_slot, as there may be many slots with @slot_nr of
* PCI_SLOT_PLACEHOLDER. The other change in semantics is user-visible,
* which is the 'address' parameter presented in sysfs will consist solely
* of a dddd:bb tuple, where dddd is the PCI domain of the %struct pci_bus
* and bb is the bus number. In other words, the devfn of the 'placeholder'
* slot will not be displayed.
*
* Bus-wide slots:
* For PCIe hotplug, the physical slot encompasses the entire secondary
@ -267,7 +268,7 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
mutex_lock(&pci_slot_mutex);
if (slot_nr == -1)
if (slot_nr == PCI_SLOT_PLACEHOLDER)
goto placeholder;
/*

3
include/linux/pci.h
View File

@ -81,6 +81,9 @@
*/
#define PCI_SLOT_ALL_DEVICES 0xfe
/* Used to identify a slot as a placeholder */
#define PCI_SLOT_PLACEHOLDER 0xff
/* pci_slot represents a physical slot */
struct pci_slot {
struct pci_bus *bus; /* Bus this slot is on */