linux-stable/drivers/pci/hotplug/s390_pci_hpc.c
Lukas Wunner 125450f814 PCI: hotplug: Embed hotplug_slot
When the PCI hotplug core and its first user, cpqphp, were introduced in
February 2002 with historic commit a8a2069f432c, cpqphp allocated a slot
struct for its internal use plus a hotplug_slot struct to be registered
with the hotplug core and linked the two with pointers:
https://git.kernel.org/tglx/history/c/a8a2069f432c

Nowadays, the predominant pattern in the tree is to embed ("subclass")
such structures in one another and cast to the containing struct with
container_of().  But it wasn't until July 2002 that container_of() was
introduced with historic commit ec4f214232cf:
https://git.kernel.org/tglx/history/c/ec4f214232cf

pnv_php, introduced in 2016, did the right thing and embedded struct
hotplug_slot in its internal struct pnv_php_slot, but all other drivers
cargo-culted cpqphp's design and linked separate structs with pointers.

Embedding structs is preferrable to linking them with pointers because
it requires fewer allocations, thereby reducing overhead and simplifying
error paths.  Casting an embedded struct to the containing struct
becomes a cheap subtraction rather than a dereference.  And having fewer
pointers reduces the risk of them pointing nowhere either accidentally
or due to an attack.

Convert all drivers to embed struct hotplug_slot in their internal slot
struct.  The "private" pointer in struct hotplug_slot thereby becomes
unused, so drop it.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>  # drivers/pci/hotplug/rpa*
Acked-by: Sebastian Ott <sebott@linux.ibm.com>        # drivers/pci/hotplug/s390*
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> # drivers/platform/x86
Cc: Len Brown <lenb@kernel.org>
Cc: Scott Murray <scott@spiteful.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Oliver OHalloran <oliveroh@au1.ibm.com>
Cc: Gavin Shan <gwshan@linux.vnet.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Corentin Chary <corentin.chary@gmail.com>
Cc: Darren Hart <dvhart@infradead.org>
2018-09-18 17:52:15 -05:00

188 lines
3.7 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* PCI Hot Plug Controller Driver for System z
*
* Copyright 2012 IBM Corp.
*
* Author(s):
* Jan Glauber <jang@linux.vnet.ibm.com>
*/
#define KMSG_COMPONENT "zpci"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/pci_hotplug.h>
#include <asm/pci_debug.h>
#include <asm/sclp.h>
#define SLOT_NAME_SIZE 10
static LIST_HEAD(s390_hotplug_slot_list);
static int zpci_fn_configured(enum zpci_state state)
{
return state == ZPCI_FN_STATE_CONFIGURED ||
state == ZPCI_FN_STATE_ONLINE;
}
/*
* struct slot - slot information for each *physical* slot
*/
struct slot {
struct list_head slot_list;
struct hotplug_slot hotplug_slot;
struct zpci_dev *zdev;
};
static inline struct slot *to_slot(struct hotplug_slot *hotplug_slot)
{
return container_of(hotplug_slot, struct slot, hotplug_slot);
}
static inline int slot_configure(struct slot *slot)
{
int ret = sclp_pci_configure(slot->zdev->fid);
zpci_dbg(3, "conf fid:%x, rc:%d\n", slot->zdev->fid, ret);
if (!ret)
slot->zdev->state = ZPCI_FN_STATE_CONFIGURED;
return ret;
}
static inline int slot_deconfigure(struct slot *slot)
{
int ret = sclp_pci_deconfigure(slot->zdev->fid);
zpci_dbg(3, "deconf fid:%x, rc:%d\n", slot->zdev->fid, ret);
if (!ret)
slot->zdev->state = ZPCI_FN_STATE_STANDBY;
return ret;
}
static int enable_slot(struct hotplug_slot *hotplug_slot)
{
struct slot *slot = to_slot(hotplug_slot);
int rc;
if (slot->zdev->state != ZPCI_FN_STATE_STANDBY)
return -EIO;
rc = slot_configure(slot);
if (rc)
return rc;
rc = zpci_enable_device(slot->zdev);
if (rc)
goto out_deconfigure;
pci_scan_slot(slot->zdev->bus, ZPCI_DEVFN);
pci_lock_rescan_remove();
pci_bus_add_devices(slot->zdev->bus);
pci_unlock_rescan_remove();
return rc;
out_deconfigure:
slot_deconfigure(slot);
return rc;
}
static int disable_slot(struct hotplug_slot *hotplug_slot)
{
struct slot *slot = to_slot(hotplug_slot);
struct pci_dev *pdev;
int rc;
if (!zpci_fn_configured(slot->zdev->state))
return -EIO;
pdev = pci_get_slot(slot->zdev->bus, ZPCI_DEVFN);
if (pdev) {
pci_stop_and_remove_bus_device_locked(pdev);
pci_dev_put(pdev);
}
rc = zpci_disable_device(slot->zdev);
if (rc)
return rc;
return slot_deconfigure(slot);
}
static int get_power_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
struct slot *slot = to_slot(hotplug_slot);
switch (slot->zdev->state) {
case ZPCI_FN_STATE_STANDBY:
*value = 0;
break;
default:
*value = 1;
break;
}
return 0;
}
static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
/* if the slot exits it always contains a function */
*value = 1;
return 0;
}
static const struct hotplug_slot_ops s390_hotplug_slot_ops = {
.enable_slot = enable_slot,
.disable_slot = disable_slot,
.get_power_status = get_power_status,
.get_adapter_status = get_adapter_status,
};
int zpci_init_slot(struct zpci_dev *zdev)
{
char name[SLOT_NAME_SIZE];
struct slot *slot;
int rc;
if (!zdev)
return 0;
slot = kzalloc(sizeof(*slot), GFP_KERNEL);
if (!slot)
goto error;
slot->zdev = zdev;
slot->hotplug_slot.ops = &s390_hotplug_slot_ops;
snprintf(name, SLOT_NAME_SIZE, "%08x", zdev->fid);
rc = pci_hp_register(&slot->hotplug_slot, zdev->bus,
ZPCI_DEVFN, name);
if (rc)
goto error_reg;
list_add(&slot->slot_list, &s390_hotplug_slot_list);
return 0;
error_reg:
kfree(slot);
error:
return -ENOMEM;
}
void zpci_exit_slot(struct zpci_dev *zdev)
{
struct slot *slot, *next;
list_for_each_entry_safe(slot, next, &s390_hotplug_slot_list,
slot_list) {
if (slot->zdev != zdev)
continue;
list_del(&slot->slot_list);
pci_hp_deregister(&slot->hotplug_slot);
kfree(slot);
}
}