[RFC PATCH v5 5/8] PCI, ACPI: hook PCI bus notifications to create/destroy PCI slots

[Jiang Liu]

Currently the pci_slot driver doesn't update PCI slot information
when PCI device hotplug event happens, which may cause memory leak
and returning stale information to user.

By hooking PCI bus notifications, this patch unifies the way to
create/destroy PCI slots when:
1) create PCI hierarchy at boot time
2) create PCI hierarchy for PCI root bridge hot-adding
3) create PCI hierarchy for PCI device hotplug hot-adding
4) destroy PCI hierarchy for PCI root bridge hot-removal
4) destroy PCI hierarchy for PCI device hot-removal

Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
---
 drivers/acpi/pci_slot.c |  197 +++++++++++++----------------------------------
 1 file changed, 54 insertions(+), 143 deletions(-)

diff --git a/drivers/acpi/pci_slot.c b/drivers/acpi/pci_slot.c
index a7d7e77..2b38f4d 100644
--- a/drivers/acpi/pci_slot.c
+++ b/drivers/acpi/pci_slot.c
@@ -9,6 +9,9 @@
  *  Copyright (C) 2007-2008 Hewlett-Packard Development Company, L.P.
  *  	Alex Chiang <achiang@xxxxxx>
  *
+ *  Copyright (C) 2013 Huawei Tech. Co., Ltd.
+ *	Jiang Liu <jiang.liu@xxxxxxxxxx>
+ *
  *  This program is free software; you can redistribute it and/or modify it
  *  under the terms and conditions of the GNU General Public License,
  *  version 2, as published by the Free Software Foundation.
@@ -28,10 +31,9 @@
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/types.h>
+#include <linux/list.h>
 #include <linux/pci.h>
 #include <linux/acpi.h>
-#include <acpi/acpi_bus.h>
-#include <acpi/acpi_drivers.h>
 #include <linux/dmi.h>
 
 static bool debug;
@@ -62,20 +64,12 @@ ACPI_MODULE_NAME("pci_slot");
 #define SLOT_NAME_SIZE 21		/* Inspired by #define in acpiphp.h */
 
 struct acpi_pci_slot {
-	acpi_handle root_handle;	/* handle of the root bridge */
 	struct pci_slot *pci_slot;	/* corresponding pci_slot */
 	struct list_head list;		/* node in the list of slots */
 };
 
-static int acpi_pci_slot_add(struct acpi_pci_root *root);
-static void acpi_pci_slot_remove(struct acpi_pci_root *root);
-
 static LIST_HEAD(slot_list);
 static DEFINE_MUTEX(slot_list_lock);
-static struct acpi_pci_driver acpi_pci_slot_driver = {
-	.add = acpi_pci_slot_add,
-	.remove = acpi_pci_slot_remove,
-};
 
 static int
 check_slot(acpi_handle handle, unsigned long long *sun)
@@ -114,21 +108,8 @@ out:
 	return device;
 }
 
-struct callback_args {
-	acpi_walk_callback	user_function;	/* only for walk_p2p_bridge */
-	struct pci_bus		*pci_bus;
-	acpi_handle		root_handle;
-};
-
 /*
- * register_slot
- *
- * Called once for each SxFy object in the namespace. Don't worry about
- * calling pci_create_slot multiple times for the same pci_bus:device,
- * since each subsequent call simply bumps the refcount on the pci_slot.
- *
- * The number of calls to pci_destroy_slot from unregister_slot is
- * symmetrical.
+ * Check whether handle has an associated slot and create PCI slot if it has.
  */
 static acpi_status
 register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
@@ -138,13 +119,23 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
 	char name[SLOT_NAME_SIZE];
 	struct acpi_pci_slot *slot;
 	struct pci_slot *pci_slot;
-	struct callback_args *parent_context = context;
-	struct pci_bus *pci_bus = parent_context->pci_bus;
+	struct pci_bus *pci_bus = context;
 
 	device = check_slot(handle, &sun);
 	if (device < 0)
 		return AE_OK;
 
+	/*
+	 * There may be multiple PCI functions associated with the same slot.
+	 * Check whether PCI slot has already been created for this PCI device.
+	 */
+	list_for_each_entry(slot, &slot_list, list) {
+		pci_slot = slot->pci_slot;
+		if (pci_slot->bus == pci_bus && pci_slot->number == device) {
+			return AE_OK;
+		}
+	}
+
 	slot = kmalloc(sizeof(*slot), GFP_KERNEL);
 	if (!slot) {
 		err("%s: cannot allocate memory\n", __func__);
@@ -159,12 +150,9 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
 		return AE_OK;
 	}
 
-	slot->root_handle = parent_context->root_handle;
 	slot->pci_slot = pci_slot;
 	INIT_LIST_HEAD(&slot->list);
-	mutex_lock(&slot_list_lock);
 	list_add(&slot->list, &slot_list);
-	mutex_unlock(&slot_list_lock);
 
 	get_device(&pci_bus->dev);
 
@@ -174,137 +162,60 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
 	return AE_OK;
 }
 
-/*
- * walk_p2p_bridge - discover and walk p2p bridges
- * @handle: points to an acpi_pci_root
- * @context: p2p_bridge_context pointer
- *
- * Note that when we call ourselves recursively, we pass a different
- * value of pci_bus in the child_context.
- */
-static acpi_status
-walk_p2p_bridge(acpi_handle handle, u32 lvl, void *context, void **rv)
-{
-	int device, function;
-	unsigned long long adr;
-	acpi_status status;
-	acpi_handle dummy_handle;
-	acpi_walk_callback user_function;
-
-	struct pci_dev *dev;
-	struct pci_bus *pci_bus;
-	struct callback_args child_context;
-	struct callback_args *parent_context = context;
-
-	pci_bus = parent_context->pci_bus;
-	user_function = parent_context->user_function;
-
-	status = acpi_get_handle(handle, "_ADR", &dummy_handle);
-	if (ACPI_FAILURE(status))
-		return AE_OK;
-
-	status = acpi_evaluate_integer(handle, "_ADR", NULL, &adr);
-	if (ACPI_FAILURE(status))
-		return AE_OK;
-
-	device = (adr >> 16) & 0xffff;
-	function = adr & 0xffff;
-
-	dev = pci_get_slot(pci_bus, PCI_DEVFN(device, function));
-	if (!dev || !dev->subordinate)
-		goto out;
-
-	child_context.pci_bus = dev->subordinate;
-	child_context.user_function = user_function;
-	child_context.root_handle = parent_context->root_handle;
-
-	dbg("p2p bridge walk, pci_bus = %x\n", dev->subordinate->number);
-	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
-				     user_function, NULL, &child_context, NULL);
-	if (ACPI_FAILURE(status))
-		goto out;
-
-	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
-				     walk_p2p_bridge, NULL, &child_context, NULL);
-out:
-	pci_dev_put(dev);
-	return AE_OK;
-}
-
-/*
- * walk_root_bridge - generic root bridge walker
- * @root: poiner of an acpi_pci_root
- * @user_function: user callback for slot objects
- *
- * Call user_function for all objects underneath this root bridge.
- * Walk p2p bridges underneath us and call user_function on those too.
- */
-static int
-walk_root_bridge(struct acpi_pci_root *root, acpi_walk_callback user_function)
+static void acpi_pci_slot_notify_add(struct pci_bus *bus)
 {
-	acpi_status status;
-	acpi_handle handle = root->device->handle;
-	struct pci_bus *pci_bus = root->bus;
-	struct callback_args context;
-
-	context.pci_bus = pci_bus;
-	context.user_function = user_function;
-	context.root_handle = handle;
-
-	dbg("root bridge walk, pci_bus = %x\n", pci_bus->number);
-	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
-				     user_function, NULL, &context, NULL);
-	if (ACPI_FAILURE(status))
-		return status;
-
-	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
-				     walk_p2p_bridge, NULL, &context, NULL);
-	if (ACPI_FAILURE(status))
-		err("%s: walk_p2p_bridge failure - %d\n", __func__, status);
-
-	return status;
-}
+	acpi_handle handle = NULL;
 
-/*
- * acpi_pci_slot_add
- * @handle: points to an acpi_pci_root
- */
-static int
-acpi_pci_slot_add(struct acpi_pci_root *root)
-{
-	acpi_status status;
-
-	status = walk_root_bridge(root, register_slot);
-	if (ACPI_FAILURE(status))
-		err("%s: register_slot failure - %d\n", __func__, status);
+	if (bus->bridge)
+		handle = DEVICE_ACPI_HANDLE(bus->bridge);
+	if (!handle)
+		return;
 
-	return status;
+	mutex_lock(&slot_list_lock);
+	acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
+			    register_slot, NULL, bus, NULL);
+	mutex_unlock(&slot_list_lock);
 }
 
-/*
- * acpi_pci_slot_remove
- * @handle: points to an acpi_pci_root
- */
-static void
-acpi_pci_slot_remove(struct acpi_pci_root *root)
+static void acpi_pci_slot_notify_del(struct pci_bus *bus)
 {
 	struct acpi_pci_slot *slot, *tmp;
-	struct pci_bus *pbus;
-	acpi_handle handle = root->device->handle;
 
 	mutex_lock(&slot_list_lock);
 	list_for_each_entry_safe(slot, tmp, &slot_list, list) {
-		if (slot->root_handle == handle) {
+		if (slot->pci_slot->bus == bus) {
 			list_del(&slot->list);
-			pbus = slot->pci_slot->bus;
 			pci_destroy_slot(slot->pci_slot);
-			put_device(&pbus->dev);
+			put_device(&bus->dev);
 			kfree(slot);
 		}
 	}
 	mutex_unlock(&slot_list_lock);
 }
 
+static int acpi_pci_slot_notify_fn(struct notifier_block *nb,
+				   unsigned long event, void *data)
+{
+	struct pci_bus *bus = data;
+
+	switch (event) {
+	case PCI_NOTIFY_POST_BUS_ADD:
+		acpi_pci_slot_notify_add(bus);
+		break;
+	case PCI_NOTIFY_PRE_BUS_DEL:
+		acpi_pci_slot_notify_del(bus);
+		break;
+	default:
+		return NOTIFY_DONE;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block acpi_pci_slot_notifier = {
+	.notifier_call = &acpi_pci_slot_notify_fn,
+};
+
 static int do_sta_before_sun(const struct dmi_system_id *d)
 {
 	info("%s detected: will evaluate _STA before calling _SUN\n", d->ident);
@@ -333,5 +244,5 @@ static struct dmi_system_id acpi_pci_slot_dmi_table[] __initdata = {
 void __init acpi_pci_slot_init(void)
 {
 	dmi_check_system(acpi_pci_slot_dmi_table);
-	acpi_pci_register_driver(&acpi_pci_slot_driver);
+	pci_bus_register_notifier(&acpi_pci_slot_notifier);
 }
-- 
1.7.9.5

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