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3757b94802
linux_dsm_epyc7002/drivers/pci/hotplug/sgi_hotplug.c
Rafael J. Wysocki 3757b94802 ACPI / hotplug: Fix concurrency issues and memory leaks 
This changeset is aimed at fixing a few different but related
problems in the ACPI hotplug infrastructure.

First of all, since notify handlers may be run in parallel with
acpi_bus_scan(), acpi_bus_trim() and acpi_bus_hot_remove_device()
and some of them are installed for ACPI handles that have no struct
acpi_device objects attached (i.e. before those objects are created),
those notify handlers have to take acpi_scan_lock to prevent races
from taking place (e.g. a struct acpi_device is found to be present
for the given ACPI handle, but right after that it is removed by
acpi_bus_trim() running in parallel to the given notify handler).
Moreover, since some of them call acpi_bus_scan() and
acpi_bus_trim(), this leads to the conclusion that acpi_scan_lock
should be acquired by the callers of these two funtions rather by
these functions themselves.

For these reasons, make all notify handlers that can handle device
addition and eject events take acpi_scan_lock and remove the
acpi_scan_lock locking from acpi_bus_scan() and acpi_bus_trim().
Accordingly, update all of their users to make sure that they
are always called under acpi_scan_lock.

Furthermore, since eject operations are carried out asynchronously
with respect to the notify events that trigger them, with the help
of acpi_bus_hot_remove_device(), even if notify handlers take the
ACPI scan lock, it still is possible that, for example,
acpi_bus_trim() will run between acpi_bus_hot_remove_device() and
the notify handler that scheduled its execution and that
acpi_bus_trim() will remove the device node passed to
acpi_bus_hot_remove_device() for ejection.  In that case, the struct
acpi_device object obtained by acpi_bus_hot_remove_device() will be
invalid and not-so-funny things will ensue.  To protect agaist that,
make the users of acpi_bus_hot_remove_device() run get_device() on
ACPI device node objects that are about to be passed to it and make
acpi_bus_hot_remove_device() run put_device() on them and check if
their ACPI handles are not NULL (make acpi_device_unregister() clear
the device nodes' ACPI handles for that check to work).

Finally, observe that acpi_os_hotplug_execute() actually can fail,
in which case its caller ought to free memory allocated for the
context object to prevent leaks from happening.  It also needs to
run put_device() on the device node that it ran get_device() on
previously in that case.  Modify the code accordingly.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
2013-02-13 14:36:47 +01:00

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2005-2006 Silicon Graphics, Inc. All rights reserved.
*
* This work was based on the 2.4/2.6 kernel development by Dick Reigner.
* Work to add BIOS PROM support was completed by Mike Habeck.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/pci_hotplug.h>
#include <linux/proc_fs.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/mutex.h>
#include <asm/sn/addrs.h>
#include <asm/sn/geo.h>
#include <asm/sn/l1.h>
#include <asm/sn/module.h>
#include <asm/sn/pcibr_provider.h>
#include <asm/sn/pcibus_provider_defs.h>
#include <asm/sn/pcidev.h>
#include <asm/sn/sn_feature_sets.h>
#include <asm/sn/sn_sal.h>
#include <asm/sn/types.h>
#include <linux/acpi.h>
#include <asm/sn/acpi.h>
#include "../pci.h"
MODULE_LICENSE("GPL");
MODULE_AUTHOR("SGI (prarit@sgi.com, dickie@sgi.com, habeck@sgi.com)");
MODULE_DESCRIPTION("SGI Altix Hot Plug PCI Controller Driver");
/* SAL call error codes. Keep in sync with prom header io/include/pcibr.h */
#define PCI_SLOT_ALREADY_UP 2 /* slot already up */
#define PCI_SLOT_ALREADY_DOWN 3 /* slot already down */
#define PCI_L1_ERR 7 /* L1 console command error */
#define PCI_EMPTY_33MHZ 15 /* empty 33 MHz bus */
#define PCIIO_ASIC_TYPE_TIOCA 4
#define PCI_L1_QSIZE 128 /* our L1 message buffer size */
#define SN_MAX_HP_SLOTS 32 /* max hotplug slots */
#define SN_SLOT_NAME_SIZE 33 /* size of name string */
/* internal list head */
static struct list_head sn_hp_list;
/* hotplug_slot struct's private pointer */
struct slot {
int device_num;
struct pci_bus *pci_bus;
/* this struct for glue internal only */
struct hotplug_slot *hotplug_slot;
struct list_head hp_list;
char physical_path[SN_SLOT_NAME_SIZE];
};
struct pcibr_slot_enable_resp {
int resp_sub_errno;
char resp_l1_msg[PCI_L1_QSIZE + 1];
};
struct pcibr_slot_disable_resp {
int resp_sub_errno;
char resp_l1_msg[PCI_L1_QSIZE + 1];
};
enum sn_pci_req_e {
PCI_REQ_SLOT_ELIGIBLE,
PCI_REQ_SLOT_DISABLE
};
static int enable_slot(struct hotplug_slot *slot);
static int disable_slot(struct hotplug_slot *slot);
static inline int get_power_status(struct hotplug_slot *slot, u8 *value);
static struct hotplug_slot_ops sn_hotplug_slot_ops = {
.enable_slot = enable_slot,
.disable_slot = disable_slot,
.get_power_status = get_power_status,
};
static DEFINE_MUTEX(sn_hotplug_mutex);
static ssize_t path_show(struct pci_slot *pci_slot, char *buf)
{
int retval = -ENOENT;
struct slot *slot = pci_slot->hotplug->private;
if (!slot)
return retval;
retval = sprintf (buf, "%s\n", slot->physical_path);
return retval;
}
static struct pci_slot_attribute sn_slot_path_attr = __ATTR_RO(path);
static int sn_pci_slot_valid(struct pci_bus *pci_bus, int device)
{
struct pcibus_info *pcibus_info;
u16 busnum, segment, ioboard_type;
pcibus_info = SN_PCIBUS_BUSSOFT_INFO(pci_bus);
/* Check to see if this is a valid slot on 'pci_bus' */
if (!(pcibus_info->pbi_valid_devices & (1 << device)))
return -EPERM;
ioboard_type = sn_ioboard_to_pci_bus(pci_bus);
busnum = pcibus_info->pbi_buscommon.bs_persist_busnum;
segment = pci_domain_nr(pci_bus) & 0xf;
/* Do not allow hotplug operations on base I/O cards */
if ((ioboard_type == L1_BRICKTYPE_IX ||
ioboard_type == L1_BRICKTYPE_IA) &&
(segment == 1 && busnum == 0 && device != 1))
return -EPERM;
return 1;
}
static int sn_pci_bus_valid(struct pci_bus *pci_bus)
{
struct pcibus_info *pcibus_info;
u32 asic_type;
u16 ioboard_type;
/* Don't register slots hanging off the TIOCA bus */
pcibus_info = SN_PCIBUS_BUSSOFT_INFO(pci_bus);
asic_type = pcibus_info->pbi_buscommon.bs_asic_type;
if (asic_type == PCIIO_ASIC_TYPE_TIOCA)
return -EPERM;
/* Only register slots in I/O Bricks that support hotplug */
ioboard_type = sn_ioboard_to_pci_bus(pci_bus);
switch (ioboard_type) {
case L1_BRICKTYPE_IX:
case L1_BRICKTYPE_PX:
case L1_BRICKTYPE_IA:
case L1_BRICKTYPE_PA:
case L1_BOARDTYPE_PCIX3SLOT:
return 1;
break;
default:
return -EPERM;
break;
}
return -EIO;
}
static int sn_hp_slot_private_alloc(struct hotplug_slot *bss_hotplug_slot,
struct pci_bus *pci_bus, int device,
char *name)
{
struct pcibus_info *pcibus_info;
struct slot *slot;
pcibus_info = SN_PCIBUS_BUSSOFT_INFO(pci_bus);
slot = kzalloc(sizeof(*slot), GFP_KERNEL);
if (!slot)
return -ENOMEM;
bss_hotplug_slot->private = slot;
slot->device_num = device;
slot->pci_bus = pci_bus;
sprintf(name, "%04x:%02x:%02x",
pci_domain_nr(pci_bus),
((u16)pcibus_info->pbi_buscommon.bs_persist_busnum),
device + 1);
sn_generate_path(pci_bus, slot->physical_path);
slot->hotplug_slot = bss_hotplug_slot;
list_add(&slot->hp_list, &sn_hp_list);
return 0;
}
static struct hotplug_slot * sn_hp_destroy(void)
{
struct slot *slot;
struct pci_slot *pci_slot;
struct hotplug_slot *bss_hotplug_slot = NULL;
list_for_each_entry(slot, &sn_hp_list, hp_list) {
bss_hotplug_slot = slot->hotplug_slot;
pci_slot = bss_hotplug_slot->pci_slot;
list_del(&((struct slot *)bss_hotplug_slot->private)->
hp_list);
sysfs_remove_file(&pci_slot->kobj,
&sn_slot_path_attr.attr);
break;
}
return bss_hotplug_slot;
}
static void sn_bus_free_data(struct pci_dev *dev)
{
struct pci_bus *subordinate_bus;
struct pci_dev *child;
/* Recursively clean up sn_irq_info structs */
if (dev->subordinate) {
subordinate_bus = dev->subordinate;
list_for_each_entry(child, &subordinate_bus->devices, bus_list)
sn_bus_free_data(child);
}
/*
* Some drivers may use dma accesses during the
* driver remove function. We release the sysdata
* areas after the driver remove functions have
* been called.
*/
sn_bus_store_sysdata(dev);
sn_pci_unfixup_slot(dev);
}
static int sn_slot_enable(struct hotplug_slot *bss_hotplug_slot,
int device_num, char **ssdt)
{
struct slot *slot = bss_hotplug_slot->private;
struct pcibus_info *pcibus_info;
struct pcibr_slot_enable_resp resp;
int rc;
pcibus_info = SN_PCIBUS_BUSSOFT_INFO(slot->pci_bus);
/*
* Power-on and initialize the slot in the SN
* PCI infrastructure.
*/
rc = sal_pcibr_slot_enable(pcibus_info, device_num, &resp, ssdt);
if (rc == PCI_SLOT_ALREADY_UP) {
dev_dbg(&slot->pci_bus->self->dev, "is already active\n");
return 1; /* return 1 to user */
}
if (rc == PCI_L1_ERR) {
dev_dbg(&slot->pci_bus->self->dev,
"L1 failure %d with message: %s",
resp.resp_sub_errno, resp.resp_l1_msg);
return -EPERM;
}
if (rc) {
dev_dbg(&slot->pci_bus->self->dev,
"insert failed with error %d sub-error %d\n",
rc, resp.resp_sub_errno);
return -EIO;
}
pcibus_info = SN_PCIBUS_BUSSOFT_INFO(slot->pci_bus);
pcibus_info->pbi_enabled_devices |= (1 << device_num);
return 0;
}
static int sn_slot_disable(struct hotplug_slot *bss_hotplug_slot,
int device_num, int action)
{
struct slot *slot = bss_hotplug_slot->private;
struct pcibus_info *pcibus_info;
struct pcibr_slot_disable_resp resp;
int rc;
pcibus_info = SN_PCIBUS_BUSSOFT_INFO(slot->pci_bus);
rc = sal_pcibr_slot_disable(pcibus_info, device_num, action, &resp);
if ((action == PCI_REQ_SLOT_ELIGIBLE) &&
(rc == PCI_SLOT_ALREADY_DOWN)) {
dev_dbg(&slot->pci_bus->self->dev, "Slot %s already inactive\n", slot->physical_path);
return 1; /* return 1 to user */
}
if ((action == PCI_REQ_SLOT_ELIGIBLE) && (rc == PCI_EMPTY_33MHZ)) {
dev_dbg(&slot->pci_bus->self->dev,
"Cannot remove last 33MHz card\n");
return -EPERM;
}
if ((action == PCI_REQ_SLOT_ELIGIBLE) && (rc == PCI_L1_ERR)) {
dev_dbg(&slot->pci_bus->self->dev,
"L1 failure %d with message \n%s\n",
resp.resp_sub_errno, resp.resp_l1_msg);
return -EPERM;
}
if ((action == PCI_REQ_SLOT_ELIGIBLE) && rc) {
dev_dbg(&slot->pci_bus->self->dev,
"remove failed with error %d sub-error %d\n",
rc, resp.resp_sub_errno);
return -EIO;
}
if ((action == PCI_REQ_SLOT_ELIGIBLE) && !rc)
return 0;
if ((action == PCI_REQ_SLOT_DISABLE) && !rc) {
pcibus_info = SN_PCIBUS_BUSSOFT_INFO(slot->pci_bus);
pcibus_info->pbi_enabled_devices &= ~(1 << device_num);
dev_dbg(&slot->pci_bus->self->dev, "remove successful\n");
return 0;
}
if ((action == PCI_REQ_SLOT_DISABLE) && rc) {
dev_dbg(&slot->pci_bus->self->dev,"remove failed rc = %d\n", rc);
}
return rc;
}
/*
* Power up and configure the slot via a SAL call to PROM.
* Scan slot (and any children), do any platform specific fixup,
* and find device driver.
*/
static int enable_slot(struct hotplug_slot *bss_hotplug_slot)
{
struct slot *slot = bss_hotplug_slot->private;
struct pci_bus *new_bus = NULL;
struct pci_dev *dev;
int func, num_funcs;
int new_ppb = 0;
int rc;
char *ssdt = NULL;
void pcibios_fixup_device_resources(struct pci_dev *);
/* Serialize the Linux PCI infrastructure */
mutex_lock(&sn_hotplug_mutex);
/*
* Power-on and initialize the slot in the SN
* PCI infrastructure. Also, retrieve the ACPI SSDT
* table for the slot (if ACPI capable PROM).
*/
rc = sn_slot_enable(bss_hotplug_slot, slot->device_num, &ssdt);
if (rc) {
mutex_unlock(&sn_hotplug_mutex);
return rc;
}
if (ssdt)
ssdt = __va(ssdt);
/* Add the new SSDT for the slot to the ACPI namespace */
if (SN_ACPI_BASE_SUPPORT() && ssdt) {
acpi_status ret;
ret = acpi_load_table((struct acpi_table_header *)ssdt);
if (ACPI_FAILURE(ret)) {
printk(KERN_ERR "%s: acpi_load_table failed (0x%x)\n",
__func__, ret);
/* try to continue on */
}
}
num_funcs = pci_scan_slot(slot->pci_bus,
PCI_DEVFN(slot->device_num + 1, 0));
if (!num_funcs) {
dev_dbg(&slot->pci_bus->self->dev, "no device in slot\n");
mutex_unlock(&sn_hotplug_mutex);
return -ENODEV;
}
/*
* Map SN resources for all functions on the card
* to the Linux PCI interface and tell the drivers
* about them.
*/
for (func = 0; func < num_funcs; func++) {
dev = pci_get_slot(slot->pci_bus,
PCI_DEVFN(slot->device_num + 1,
PCI_FUNC(func)));
if (dev) {
/* Need to do slot fixup on PPB before fixup of children
* (PPB's pcidev_info needs to be in pcidev_info list
* before child's SN_PCIDEV_INFO() call to setup
* pdi_host_pcidev_info).
*/
pcibios_fixup_device_resources(dev);
if (SN_ACPI_BASE_SUPPORT())
sn_acpi_slot_fixup(dev);
else
sn_io_slot_fixup(dev);
if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
pci_hp_add_bridge(dev);
if (dev->subordinate) {
new_bus = dev->subordinate;
new_ppb = 1;
}
}
pci_dev_put(dev);
}
}
/*
* Add the slot's devices to the ACPI infrastructure */
if (SN_ACPI_BASE_SUPPORT() && ssdt) {
unsigned long long adr;
struct acpi_device *pdevice;
acpi_handle phandle;
acpi_handle chandle = NULL;
acpi_handle rethandle;
acpi_status ret;
phandle = PCI_CONTROLLER(slot->pci_bus)->acpi_handle;
if (acpi_bus_get_device(phandle, &pdevice)) {
dev_dbg(&slot->pci_bus->self->dev,
"no parent device, assuming NULL\n");
pdevice = NULL;
}
acpi_scan_lock_acquire();
/*
* Walk the rootbus node's immediate children looking for
* the slot's device node(s). There can be more than
* one for multifunction devices.
*/
for (;;) {
rethandle = NULL;
ret = acpi_get_next_object(ACPI_TYPE_DEVICE,
phandle, chandle,
&rethandle);
if (ret == AE_NOT_FOUND || rethandle == NULL)
break;
chandle = rethandle;
ret = acpi_evaluate_integer(chandle, METHOD_NAME__ADR,
NULL, &adr);
if (ACPI_SUCCESS(ret) &&
(adr>>16) == (slot->device_num + 1)) {
ret = acpi_bus_scan(chandle);
if (ACPI_FAILURE(ret)) {
printk(KERN_ERR "%s: acpi_bus_scan "
"failed (0x%x) for slot %d "
"func %d\n", __func__,
ret, (int)(adr>>16),
(int)(adr&0xffff));
/* try to continue on */
}
}
}
acpi_scan_lock_release();
}
/* Call the driver for the new device */
pci_bus_add_devices(slot->pci_bus);
/* Call the drivers for the new devices subordinate to PPB */
if (new_ppb)
pci_bus_add_devices(new_bus);
mutex_unlock(&sn_hotplug_mutex);
if (rc == 0)
dev_dbg(&slot->pci_bus->self->dev,
"insert operation successful\n");
else
dev_dbg(&slot->pci_bus->self->dev,
"insert operation failed rc = %d\n", rc);
return rc;
}
static int disable_slot(struct hotplug_slot *bss_hotplug_slot)
{
struct slot *slot = bss_hotplug_slot->private;
struct pci_dev *dev;
int func;
int rc;
acpi_owner_id ssdt_id = 0;
/* Acquire update access to the bus */
mutex_lock(&sn_hotplug_mutex);
/* is it okay to bring this slot down? */
rc = sn_slot_disable(bss_hotplug_slot, slot->device_num,
PCI_REQ_SLOT_ELIGIBLE);
if (rc)
goto leaving;
/* free the ACPI resources for the slot */
if (SN_ACPI_BASE_SUPPORT() &&
PCI_CONTROLLER(slot->pci_bus)->acpi_handle) {
unsigned long long adr;
struct acpi_device *device;
acpi_handle phandle;
acpi_handle chandle = NULL;
acpi_handle rethandle;
acpi_status ret;
/* Get the rootbus node pointer */
phandle = PCI_CONTROLLER(slot->pci_bus)->acpi_handle;
acpi_scan_lock_acquire();
/*
* Walk the rootbus node's immediate children looking for
* the slot's device node(s). There can be more than
* one for multifunction devices.
*/
for (;;) {
rethandle = NULL;
ret = acpi_get_next_object(ACPI_TYPE_DEVICE,
phandle, chandle,
&rethandle);
if (ret == AE_NOT_FOUND || rethandle == NULL)
break;
chandle = rethandle;
ret = acpi_evaluate_integer(chandle,
METHOD_NAME__ADR,
NULL, &adr);
if (ACPI_SUCCESS(ret) &&
(adr>>16) == (slot->device_num + 1)) {
/* retain the owner id */
acpi_get_id(chandle, &ssdt_id);
ret = acpi_bus_get_device(chandle,
&device);
if (ACPI_SUCCESS(ret))
acpi_bus_trim(device);
}
}
acpi_scan_lock_release();
}
/* Free the SN resources assigned to the Linux device.*/
for (func = 0; func < 8; func++) {
dev = pci_get_slot(slot->pci_bus,
PCI_DEVFN(slot->device_num + 1,
PCI_FUNC(func)));
if (dev) {
sn_bus_free_data(dev);
pci_stop_and_remove_bus_device(dev);
pci_dev_put(dev);
}
}
/* Remove the SSDT for the slot from the ACPI namespace */
if (SN_ACPI_BASE_SUPPORT() && ssdt_id) {
acpi_status ret;
ret = acpi_unload_table_id(ssdt_id);
if (ACPI_FAILURE(ret)) {
printk(KERN_ERR "%s: acpi_unload_table_id "
"failed (0x%x) for id %d\n",
__func__, ret, ssdt_id);
/* try to continue on */
}
}
/* free the collected sysdata pointers */
sn_bus_free_sysdata();
/* Deactivate slot */
rc = sn_slot_disable(bss_hotplug_slot, slot->device_num,
PCI_REQ_SLOT_DISABLE);
leaving:
/* Release the bus lock */
mutex_unlock(&sn_hotplug_mutex);
return rc;
}
static inline int get_power_status(struct hotplug_slot *bss_hotplug_slot,
u8 *value)
{
struct slot *slot = bss_hotplug_slot->private;
struct pcibus_info *pcibus_info;
u32 power;
pcibus_info = SN_PCIBUS_BUSSOFT_INFO(slot->pci_bus);
mutex_lock(&sn_hotplug_mutex);
power = pcibus_info->pbi_enabled_devices & (1 << slot->device_num);
*value = power ? 1 : 0;
mutex_unlock(&sn_hotplug_mutex);
return 0;
}
static void sn_release_slot(struct hotplug_slot *bss_hotplug_slot)
{
kfree(bss_hotplug_slot->info);
kfree(bss_hotplug_slot->private);
kfree(bss_hotplug_slot);
}
static int sn_hotplug_slot_register(struct pci_bus *pci_bus)
{
int device;
struct pci_slot *pci_slot;
struct hotplug_slot *bss_hotplug_slot;
char name[SN_SLOT_NAME_SIZE];
int rc = 0;
/*
* Currently only four devices are supported,
* in the future there maybe more -- up to 32.
*/
for (device = 0; device < SN_MAX_HP_SLOTS ; device++) {
if (sn_pci_slot_valid(pci_bus, device) != 1)
continue;
bss_hotplug_slot = kzalloc(sizeof(*bss_hotplug_slot),
GFP_KERNEL);
if (!bss_hotplug_slot) {
rc = -ENOMEM;
goto alloc_err;
}
bss_hotplug_slot->info =
kzalloc(sizeof(struct hotplug_slot_info),
GFP_KERNEL);
if (!bss_hotplug_slot->info) {
rc = -ENOMEM;
goto alloc_err;
}
if (sn_hp_slot_private_alloc(bss_hotplug_slot,
pci_bus, device, name)) {
rc = -ENOMEM;
goto alloc_err;
}
bss_hotplug_slot->ops = &sn_hotplug_slot_ops;
bss_hotplug_slot->release = &sn_release_slot;
rc = pci_hp_register(bss_hotplug_slot, pci_bus, device, name);
if (rc)
goto register_err;
pci_slot = bss_hotplug_slot->pci_slot;
rc = sysfs_create_file(&pci_slot->kobj,
&sn_slot_path_attr.attr);
if (rc)
goto register_err;
}
dev_dbg(&pci_bus->self->dev, "Registered bus with hotplug\n");
return rc;
register_err:
dev_dbg(&pci_bus->self->dev, "bus failed to register with err = %d\n",
rc);
alloc_err:
if (rc == -ENOMEM)
dev_dbg(&pci_bus->self->dev, "Memory allocation error\n");
/* destroy THIS element */
if (bss_hotplug_slot)
sn_release_slot(bss_hotplug_slot);
/* destroy anything else on the list */
while ((bss_hotplug_slot = sn_hp_destroy()))
pci_hp_deregister(bss_hotplug_slot);
return rc;
}
static int __init sn_pci_hotplug_init(void)
{
struct pci_bus *pci_bus = NULL;
int rc;
int registered = 0;
if (!sn_prom_feature_available(PRF_HOTPLUG_SUPPORT)) {
printk(KERN_ERR "%s: PROM version does not support hotplug.\n",
__func__);
return -EPERM;
}
INIT_LIST_HEAD(&sn_hp_list);
while ((pci_bus = pci_find_next_bus(pci_bus))) {
if (!pci_bus->sysdata)
continue;
rc = sn_pci_bus_valid(pci_bus);
if (rc != 1) {
dev_dbg(&pci_bus->self->dev, "not a valid hotplug bus\n");
continue;
}
dev_dbg(&pci_bus->self->dev, "valid hotplug bus\n");
rc = sn_hotplug_slot_register(pci_bus);
if (!rc) {
registered = 1;
} else {
registered = 0;
break;
}
}
return registered == 1 ? 0 : -ENODEV;
}
static void __exit sn_pci_hotplug_exit(void)
{
struct hotplug_slot *bss_hotplug_slot;
while ((bss_hotplug_slot = sn_hp_destroy()))
pci_hp_deregister(bss_hotplug_slot);
if (!list_empty(&sn_hp_list))
printk(KERN_ERR "%s: internal list is not empty\n", __FILE__);
}
module_init(sn_pci_hotplug_init);
module_exit(sn_pci_hotplug_exit);
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