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linux/drivers/pci/hotplug/acpiphp_core.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

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// SPDX-License-Identifier: GPL-2.0+
/*
* ACPI PCI Hot Plug Controller Driver
*
* Copyright (C) 1995,2001 Compaq Computer Corporation
* Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
* Copyright (C) 2001 IBM Corp.
* Copyright (C) 2002 Hiroshi Aono (h-aono@ap.jp.nec.com)
* Copyright (C) 2002,2003 Takayoshi Kochi (t-kochi@bq.jp.nec.com)
* Copyright (C) 2002,2003 NEC Corporation
* Copyright (C) 2003-2005 Matthew Wilcox (matthew.wilcox@hp.com)
* Copyright (C) 2003-2005 Hewlett Packard
*
* All rights reserved.
*
* Send feedback to <kristen.c.accardi@intel.com>
*
*/
#define pr_fmt(fmt) "acpiphp: " fmt
#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/pci-acpi.h>
#include <linux/pci_hotplug.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include "acpiphp.h"
/* name size which is used for entries in pcihpfs */
#define SLOT_NAME_SIZE 21 /* {_SUN} */
bool acpiphp_disabled;
/* local variables */
static struct acpiphp_attention_info *attention_info;
#define DRIVER_VERSION "0.5"
#define DRIVER_AUTHOR "Greg Kroah-Hartman <gregkh@us.ibm.com>, Takayoshi Kochi <t-kochi@bq.jp.nec.com>, Matthew Wilcox <willy@hp.com>"
#define DRIVER_DESC "ACPI Hot Plug PCI Controller Driver"
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
MODULE_PARM_DESC(disable, "disable acpiphp driver");
module_param_named(disable, acpiphp_disabled, bool, 0444);
static int enable_slot(struct hotplug_slot *slot);
static int disable_slot(struct hotplug_slot *slot);
static int set_attention_status(struct hotplug_slot *slot, u8 value);
static int get_power_status(struct hotplug_slot *slot, u8 *value);
static int get_attention_status(struct hotplug_slot *slot, u8 *value);
static int get_latch_status(struct hotplug_slot *slot, u8 *value);
static int get_adapter_status(struct hotplug_slot *slot, u8 *value);
static const struct hotplug_slot_ops acpi_hotplug_slot_ops = {
.enable_slot = enable_slot,
.disable_slot = disable_slot,
.set_attention_status = set_attention_status,
.get_power_status = get_power_status,
.get_attention_status = get_attention_status,
.get_latch_status = get_latch_status,
.get_adapter_status = get_adapter_status,
};
/**
* acpiphp_register_attention - set attention LED callback
* @info: must be completely filled with LED callbacks
*
* Description: This is used to register a hardware specific ACPI
* driver that manipulates the attention LED. All the fields in
* info must be set.
*/
int acpiphp_register_attention(struct acpiphp_attention_info *info)
{
int retval = -EINVAL;
if (info && info->owner && info->set_attn &&
info->get_attn && !attention_info) {
retval = 0;
attention_info = info;
}
return retval;
}
EXPORT_SYMBOL_GPL(acpiphp_register_attention);
/**
* acpiphp_unregister_attention - unset attention LED callback
* @info: must match the pointer used to register
*
* Description: This is used to un-register a hardware specific acpi
* driver that manipulates the attention LED. The pointer to the
* info struct must be the same as the one used to set it.
*/
int acpiphp_unregister_attention(struct acpiphp_attention_info *info)
{
int retval = -EINVAL;
if (info && attention_info == info) {
attention_info = NULL;
retval = 0;
}
return retval;
}
EXPORT_SYMBOL_GPL(acpiphp_unregister_attention);
/**
* enable_slot - power on and enable a slot
* @hotplug_slot: slot to enable
*
* Actual tasks are done in acpiphp_enable_slot()
*/
static int enable_slot(struct hotplug_slot *hotplug_slot)
{
struct slot *slot = to_slot(hotplug_slot);
pr_debug("%s - physical_slot = %s\n", __func__, slot_name(slot));
/* enable the specified slot */
return acpiphp_enable_slot(slot->acpi_slot);
}
/**
* disable_slot - disable and power off a slot
* @hotplug_slot: slot to disable
*
* Actual tasks are done in acpiphp_disable_slot()
*/
static int disable_slot(struct hotplug_slot *hotplug_slot)
{
struct slot *slot = to_slot(hotplug_slot);
pr_debug("%s - physical_slot = %s\n", __func__, slot_name(slot));
/* disable the specified slot */
return acpiphp_disable_slot(slot->acpi_slot);
}
/**
* set_attention_status - set attention LED
* @hotplug_slot: slot to set attention LED on
* @status: value to set attention LED to (0 or 1)
*
* attention status LED, so we use a callback that
* was registered with us. This allows hardware specific
* ACPI implementations to blink the light for us.
*/
static int set_attention_status(struct hotplug_slot *hotplug_slot, u8 status)
{
int retval = -ENODEV;
pr_debug("%s - physical_slot = %s\n", __func__,
hotplug_slot_name(hotplug_slot));
if (attention_info && try_module_get(attention_info->owner)) {
retval = attention_info->set_attn(hotplug_slot, status);
module_put(attention_info->owner);
} else
attention_info = NULL;
return retval;
}
/**
* get_power_status - get power status of a slot
* @hotplug_slot: slot to get status
* @value: pointer to store status
*
* Some platforms may not implement _STA method properly.
* In that case, the value returned may not be reliable.
*/
static int get_power_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
struct slot *slot = to_slot(hotplug_slot);
pr_debug("%s - physical_slot = %s\n", __func__, slot_name(slot));
*value = acpiphp_get_power_status(slot->acpi_slot);
return 0;
}
/**
* get_attention_status - get attention LED status
* @hotplug_slot: slot to get status from
* @value: returns with value of attention LED
*
* ACPI doesn't have known method to determine the state
* of the attention status LED, so we use a callback that
* was registered with us. This allows hardware specific
* ACPI implementations to determine its state.
*/
static int get_attention_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
int retval = -EINVAL;
pr_debug("%s - physical_slot = %s\n", __func__,
hotplug_slot_name(hotplug_slot));
if (attention_info && try_module_get(attention_info->owner)) {
retval = attention_info->get_attn(hotplug_slot, value);
module_put(attention_info->owner);
} else
attention_info = NULL;
return retval;
}
/**
* get_latch_status - get latch status of a slot
* @hotplug_slot: slot to get status
* @value: pointer to store status
*
* ACPI doesn't provide any formal means to access latch status.
* Instead, we fake latch status from _STA.
*/
static int get_latch_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
struct slot *slot = to_slot(hotplug_slot);
pr_debug("%s - physical_slot = %s\n", __func__, slot_name(slot));
*value = acpiphp_get_latch_status(slot->acpi_slot);
return 0;
}
/**
* get_adapter_status - get adapter status of a slot
* @hotplug_slot: slot to get status
* @value: pointer to store status
*
* ACPI doesn't provide any formal means to access adapter status.
* Instead, we fake adapter status from _STA.
*/
static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
struct slot *slot = to_slot(hotplug_slot);
pr_debug("%s - physical_slot = %s\n", __func__, slot_name(slot));
*value = acpiphp_get_adapter_status(slot->acpi_slot);
return 0;
}
/* callback routine to initialize 'struct slot' for each slot */
int acpiphp_register_hotplug_slot(struct acpiphp_slot *acpiphp_slot,
unsigned int sun)
{
struct slot *slot;
int retval = -ENOMEM;
char name[SLOT_NAME_SIZE];
slot = kzalloc(sizeof(*slot), GFP_KERNEL);
if (!slot)
goto error;
slot->hotplug_slot.ops = &acpi_hotplug_slot_ops;
slot->acpi_slot = acpiphp_slot;
acpiphp_slot->slot = slot;
slot->sun = sun;
snprintf(name, SLOT_NAME_SIZE, "%u", sun);
retval = pci_hp_register(&slot->hotplug_slot, acpiphp_slot->bus,
acpiphp_slot->device, name);
if (retval == -EBUSY)
goto error_slot;
if (retval) {
pr_err("pci_hp_register failed with error %d\n", retval);
goto error_slot;
}
pr_info("Slot [%s] registered\n", slot_name(slot));
return 0;
error_slot:
kfree(slot);
error:
return retval;
}
void acpiphp_unregister_hotplug_slot(struct acpiphp_slot *acpiphp_slot)
{
struct slot *slot = acpiphp_slot->slot;
pr_info("Slot [%s] unregistered\n", slot_name(slot));
pci_hp_deregister(&slot->hotplug_slot);
kfree(slot);
}
void __init acpiphp_init(void)
{
pr_info(DRIVER_DESC " version: " DRIVER_VERSION "%s\n",
acpiphp_disabled ? ", disabled by user; please report a bug"
: "");
}
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