ACPI / hotplug / PCI: Hotplug context objects for bridges and functions

When either a new hotplug bridge or a new hotplug function is added
by the ACPI-based PCI hotplug (ACPIPHP) code, attach a context object
to its ACPI handle to store hotplug-related information in it.  To
start with, put the handle's bridge and function pointers into that
object.  Count references to the context objects and drop them when
they are not needed any more.

First of all, this makes it possible to find out if the given bridge
has been registered as a function already in a much more
straightforward way and acpiphp_bridge_handle_to_function() can be
dropped (Yay!).

This also will allow some more simplifications to be made going
forward.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/pci/hotplug/acpiphp.h

@@ -49,6 +49,7 @@
 #define info(format, arg...) printk(KERN_INFO "%s: " format, MY_NAME , ## arg)
 #define warn(format, arg...) printk(KERN_WARNING "%s: " format, MY_NAME , ## arg)
 
+struct acpiphp_context;
 struct acpiphp_bridge;
 struct acpiphp_slot;
 
@@ -77,6 +78,7 @@ struct acpiphp_bridge {
 	struct kref ref;
 	acpi_handle handle;
 
+	struct acpiphp_context *context;
 	/* Ejectable PCI-to-PCI bridge (PCI bridge and PCI function) */
 	struct acpiphp_func *func;
 
@@ -119,6 +121,7 @@ struct acpiphp_slot {
  * typically 8 objects per slot (i.e. for each PCI function)
  */
 struct acpiphp_func {
+	struct acpiphp_context *context;
 	struct acpiphp_slot *slot;	/* parent */
 
 	struct list_head sibling;
@@ -128,6 +131,13 @@ struct acpiphp_func {
 	u32		flags;		/* see below */
 };
 
+struct acpiphp_context {
+	acpi_handle handle;
+	struct acpiphp_func *func;
+	struct acpiphp_bridge *bridge;
+	unsigned int refcount;
+};
+
 /*
  * struct acpiphp_attention_info - device specific attention registration
  *

drivers/pci/hotplug/acpiphp_glue.c

@@ -55,6 +55,7 @@
 
 static LIST_HEAD(bridge_list);
 static DEFINE_MUTEX(bridge_mutex);
+static DEFINE_MUTEX(acpiphp_context_lock);
 
 #define MY_NAME "acpiphp_glue"
 
@@ -79,6 +80,74 @@ is_pci_dock_device(acpi_handle handle, u32 lvl, void *context, void **rv)
 	}
 }
 
+static void acpiphp_context_handler(acpi_handle handle, void *context)
+{
+	/* Intentionally empty. */
+}
+
+/**
+ * acpiphp_init_context - Create hotplug context and grab a reference to it.
+ * @handle: ACPI object handle to create the context for.
+ *
+ * Call under acpiphp_context_lock.
+ */
+static struct acpiphp_context *acpiphp_init_context(acpi_handle handle)
+{
+	struct acpiphp_context *context;
+	acpi_status status;
+
+	context = kzalloc(sizeof(*context), GFP_KERNEL);
+	if (!context)
+		return NULL;
+
+	context->handle = handle;
+	context->refcount = 1;
+	status = acpi_attach_data(handle, acpiphp_context_handler, context);
+	if (ACPI_FAILURE(status)) {
+		kfree(context);
+		return NULL;
+	}
+	return context;
+}
+
+/**
+ * acpiphp_get_context - Get hotplug context and grab a reference to it.
+ * @handle: ACPI object handle to get the context for.
+ *
+ * Call under acpiphp_context_lock.
+ */
+static struct acpiphp_context *acpiphp_get_context(acpi_handle handle)
+{
+	struct acpiphp_context *context = NULL;
+	acpi_status status;
+	void *data;
+
+	status = acpi_get_data(handle, acpiphp_context_handler, &data);
+	if (ACPI_SUCCESS(status)) {
+		context = data;
+		context->refcount++;
+	}
+	return context;
+}
+
+/**
+ * acpiphp_put_context - Drop a reference to ACPI hotplug context.
+ * @handle: ACPI object handle to put the context for.
+ *
+ * The context object is removed if there are no more references to it.
+ *
+ * Call under acpiphp_context_lock.
+ */
+static void acpiphp_put_context(struct acpiphp_context *context)
+{
+	if (--context->refcount)
+		return;
+
+	WARN_ON(context->func || context->bridge);
+	acpi_detach_data(context->handle, acpiphp_context_handler);
+	kfree(context);
+}
+
 static inline void get_bridge(struct acpiphp_bridge *bridge)
 {
 	kref_get(&bridge->ref);
@@ -91,25 +160,37 @@ static inline void put_bridge(struct acpiphp_bridge *bridge)
 
 static void free_bridge(struct kref *kref)
 {
+	struct acpiphp_context *context;
 	struct acpiphp_bridge *bridge;
 	struct acpiphp_slot *slot, *next;
 	struct acpiphp_func *func, *tmp;
 
+	mutex_lock(&acpiphp_context_lock);
+
 	bridge = container_of(kref, struct acpiphp_bridge, ref);
 
 	list_for_each_entry_safe(slot, next, &bridge->slots, node) {
 		list_for_each_entry_safe(func, tmp, &slot->funcs, sibling) {
+			context = func->context;
+			context->func = NULL;
+			acpiphp_put_context(context);
 			kfree(func);
 		}
 		kfree(slot);
 	}
 
-	/* Release reference acquired by acpiphp_bridge_handle_to_function() */
+	/* Release the reference acquired by acpiphp_enumerate_slots(). */
 	if ((bridge->flags & BRIDGE_HAS_EJ0) && bridge->func)
 		put_bridge(bridge->func->slot->bridge);
+
 	put_device(&bridge->pci_bus->dev);
 	pci_dev_put(bridge->pci_dev);
+	context = bridge->context;
+	context->bridge = NULL;
+	acpiphp_put_context(context);
 	kfree(bridge);
+
+	mutex_unlock(&acpiphp_context_lock);
 }
 
 /*
@@ -194,10 +275,11 @@ static void acpiphp_dock_release(void *data)
 }
 
 /* callback routine to register each ACPI PCI slot object */
-static acpi_status
-register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
+static acpi_status register_slot(acpi_handle handle, u32 lvl, void *data,
+				 void **rv)
 {
-	struct acpiphp_bridge *bridge = (struct acpiphp_bridge *)context;
+	struct acpiphp_bridge *bridge = data;
+	struct acpiphp_context *context;
 	struct acpiphp_slot *slot;
 	struct acpiphp_func *newfunc;
 	acpi_status status = AE_OK;
@@ -230,6 +312,18 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
 	newfunc->handle = handle;
 	newfunc->function = function;
 
+	mutex_lock(&acpiphp_context_lock);
+	context = acpiphp_init_context(handle);
+	if (!context) {
+		mutex_unlock(&acpiphp_context_lock);
+		acpi_handle_err(handle, "No hotplug context\n");
+		kfree(newfunc);
+		return AE_NOT_EXIST;
+	}
+	newfunc->context = context;
+	context->func = newfunc;
+	mutex_unlock(&acpiphp_context_lock);
+
 	if (acpi_has_method(handle, "_EJ0"))
 		newfunc->flags = FUNC_HAS_EJ0;
 
@@ -266,8 +360,8 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
 	if (!found) {
 		slot = kzalloc(sizeof(struct acpiphp_slot), GFP_KERNEL);
 		if (!slot) {
-			kfree(newfunc);
-			return AE_NO_MEMORY;
+			status = AE_NO_MEMORY;
+			goto err_out;
 		}
 
 		slot->bridge = bridge;
@@ -291,7 +385,9 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
 			else
 				warn("acpiphp_register_hotplug_slot failed "
 					"(err code = 0x%x)\n", retval);
-			goto err_exit;
+
+			status = AE_OK;
+			goto err;
 		}
 	}
 
@@ -329,15 +425,20 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
 
 	return AE_OK;
 
- err_exit:
+ err:
 	bridge->nr_slots--;
 	mutex_lock(&bridge_mutex);
 	list_del(&slot->node);
 	mutex_unlock(&bridge_mutex);
 	kfree(slot);
-	kfree(newfunc);
 
-	return AE_OK;
+ err_out:
+	mutex_lock(&acpiphp_context_lock);
+	context->func = NULL;
+	acpiphp_put_context(context);
+	mutex_unlock(&acpiphp_context_lock);
+	kfree(newfunc);
+	return status;
 }
 
 
@@ -352,32 +453,6 @@ static int detect_ejectable_slots(acpi_handle handle)
 	return found;
 }
 
-
-/* find acpiphp_func from acpiphp_bridge */
-static struct acpiphp_func *acpiphp_bridge_handle_to_function(acpi_handle handle)
-{
-	struct acpiphp_bridge *bridge;
-	struct acpiphp_slot *slot;
-	struct acpiphp_func *func = NULL;
-
-	mutex_lock(&bridge_mutex);
-	list_for_each_entry(bridge, &bridge_list, list) {
-		list_for_each_entry(slot, &bridge->slots, node) {
-			list_for_each_entry(func, &slot->funcs, sibling) {
-				if (func->handle == handle) {
-					get_bridge(func->slot->bridge);
-					mutex_unlock(&bridge_mutex);
-					return func;
-				}
-			}
-		}
-	}
-	mutex_unlock(&bridge_mutex);
-
-	return NULL;
-}
-
-
 static struct acpiphp_bridge *acpiphp_handle_to_bridge(acpi_handle handle)
 {
 	struct acpiphp_bridge *bridge;
@@ -1108,6 +1183,7 @@ static void handle_hotplug_event_func(acpi_handle handle, u32 type,
  */
 void acpiphp_enumerate_slots(struct pci_bus *bus)
 {
+	struct acpiphp_context *context;
 	struct acpiphp_bridge *bridge;
 	acpi_handle handle;
 	acpi_status status;
@@ -1120,8 +1196,8 @@ void acpiphp_enumerate_slots(struct pci_bus *bus)
 		return;
 
 	bridge = kzalloc(sizeof(struct acpiphp_bridge), GFP_KERNEL);
-	if (bridge == NULL) {
-		err("out of memory\n");
+	if (!bridge) {
+		acpi_handle_err(handle, "No memory for bridge object\n");
 		return;
 	}
 
@@ -1131,6 +1207,21 @@ void acpiphp_enumerate_slots(struct pci_bus *bus)
 	bridge->pci_dev = pci_dev_get(bus->self);
 	bridge->pci_bus = bus;
 
+	mutex_lock(&acpiphp_context_lock);
+	context = acpiphp_get_context(handle);
+	if (!context) {
+		context = acpiphp_init_context(handle);
+		if (!context) {
+			mutex_unlock(&acpiphp_context_lock);
+			acpi_handle_err(handle, "No hotplug context\n");
+			kfree(bridge);
+			return;
+		}
+	}
+	bridge->context = context;
+	context->bridge = bridge;
+	mutex_unlock(&acpiphp_context_lock);
+
 	/*
 	 * Grab a ref to the subordinate PCI bus in case the bus is
 	 * removed via PCI core logical hotplug. The ref pins the bus
@@ -1169,13 +1260,15 @@ void acpiphp_enumerate_slots(struct pci_bus *bus)
 
 	dbg("found ejectable p2p bridge\n");
 	bridge->flags |= BRIDGE_HAS_EJ0;
-	bridge->func = acpiphp_bridge_handle_to_function(bridge->handle);
-	if (bridge->func) {
-		status = acpi_remove_notify_handler(bridge->func->handle,
-						    ACPI_SYSTEM_NOTIFY,
+	if (context->func) {
+		get_bridge(context->func->slot->bridge);
+		bridge->func = context->func;
+		handle = context->handle;
+		WARN_ON(bridge->handle != handle);
+		status = acpi_remove_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
 						    handle_hotplug_event_func);
 		if (ACPI_FAILURE(status))
-			acpi_handle_err(bridge->func->handle,
+			acpi_handle_err(handle,
 					"failed to remove notify handler\n");
 	}
 	return;