linux-kernel - [PATCH 17/24][Resend] ACPICA: Introduce acpi_get_data_full() and rework acpi_get

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Date:	Tue, 04 Feb 2014 00:34:19 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Cc:	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Aaron Lu <aaron.lu@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>
Subject: [PATCH 17/24][Resend] ACPICA: Introduce acpi_get_data_full() and rework acpi_get_data()

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Introduce a new function, acpi_get_data_full(), working in analogy
with acpi_get_data() except that it can execute a callback provided
as its 4th argument right after acpi_ns_get_attached_data() has
returned a success.

That will allow Linux to reference count the object pointed to by
*data before the namespace mutex is released so as to ensure that it
will not be freed going forward until the reference to it acquired
by acpi_get_data_full() is dropped.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Tested-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
---
 drivers/acpi/acpica/nsxfeval.c |   33 ++++++++++++++++++++++++++++++---
 include/acpi/acpixf.h          |    4 ++++
 2 files changed, 34 insertions(+), 3 deletions(-)

Index: linux-pm/drivers/acpi/acpica/nsxfeval.c
===================================================================
--- linux-pm.orig/drivers/acpi/acpica/nsxfeval.c
+++ linux-pm/drivers/acpi/acpica/nsxfeval.c
@@ -923,19 +923,22 @@ ACPI_EXPORT_SYMBOL(acpi_detach_data)
 
 /*******************************************************************************
  *
- * FUNCTION:    acpi_get_data
+ * FUNCTION:    acpi_get_data_full
  *
  * PARAMETERS:  obj_handle          - Namespace node
  *              handler             - Handler used in call to attach_data
  *              data                - Where the data is returned
+ *              callback            - function to execute before returning
  *
  * RETURN:      Status
  *
- * DESCRIPTION: Retrieve data that was previously attached to a namespace node.
+ * DESCRIPTION: Retrieve data that was previously attached to a namespace node
+ *              and execute a callback before returning.
  *
  ******************************************************************************/
 acpi_status
-acpi_get_data(acpi_handle obj_handle, acpi_object_handler handler, void **data)
+acpi_get_data_full(acpi_handle obj_handle, acpi_object_handler handler,
+		   void **data, void (*callback)(void *))
 {
 	struct acpi_namespace_node *node;
 	acpi_status status;
@@ -960,10 +963,34 @@ acpi_get_data(acpi_handle obj_handle, ac
 	}
 
 	status = acpi_ns_get_attached_data(node, handler, data);
+	if (ACPI_SUCCESS(status) && callback) {
+		callback(*data);
+	}
 
 unlock_and_exit:
 	(void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
 	return (status);
 }
 
+ACPI_EXPORT_SYMBOL(acpi_get_data_full)
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_get_data
+ *
+ * PARAMETERS:  obj_handle          - Namespace node
+ *              handler             - Handler used in call to attach_data
+ *              data                - Where the data is returned
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Retrieve data that was previously attached to a namespace node.
+ *
+ ******************************************************************************/
+acpi_status
+acpi_get_data(acpi_handle obj_handle, acpi_object_handler handler, void **data)
+{
+	return acpi_get_data_full(obj_handle, handler, data, NULL);
+}
+
 ACPI_EXPORT_SYMBOL(acpi_get_data)
Index: linux-pm/include/acpi/acpixf.h
===================================================================
--- linux-pm.orig/include/acpi/acpixf.h
+++ linux-pm/include/acpi/acpixf.h
@@ -230,6 +230,10 @@ acpi_attach_data(acpi_handle object, acp
 acpi_status acpi_detach_data(acpi_handle object, acpi_object_handler handler);
 
 acpi_status
+acpi_get_data_full(acpi_handle object, acpi_object_handler handler, void **data,
+		   void (*callback)(void *));
+
+acpi_status
 acpi_get_data(acpi_handle object, acpi_object_handler handler, void **data);
 
 acpi_status
--
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