ACPICA: Fix AcpiWalkNamespace race condition with table unload
Added a reader/writer locking mechanism to allow multiple
concurrent namespace walks (readers), but a dynamic table unload
will have exclusive access to the namespace. This fixes a problem
where a table unload could delete the portion of the namespace that
is currently being examined by a walk. Adds a new file, utlock.c
that implements the reader/writer lock mechanism. ACPICA BZ 749.
http://www.acpica.org/bugzilla/show_bug.cgi?id=749
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/acpica/utmutex.c b/drivers/acpi/acpica/utmutex.c
index 14eb52c..26c93a7 100644
--- a/drivers/acpi/acpica/utmutex.c
+++ b/drivers/acpi/acpica/utmutex.c
@@ -60,7 +60,8 @@
*
* RETURN: Status
*
- * DESCRIPTION: Create the system mutex objects.
+ * DESCRIPTION: Create the system mutex objects. This includes mutexes,
+ * spin locks, and reader/writer locks.
*
******************************************************************************/
@@ -71,9 +72,8 @@
ACPI_FUNCTION_TRACE(ut_mutex_initialize);
- /*
- * Create each of the predefined mutex objects
- */
+ /* Create each of the predefined mutex objects */
+
for (i = 0; i < ACPI_NUM_MUTEX; i++) {
status = acpi_ut_create_mutex(i);
if (ACPI_FAILURE(status)) {
@@ -86,6 +86,9 @@
spin_lock_init(acpi_gbl_gpe_lock);
spin_lock_init(acpi_gbl_hardware_lock);
+ /* Create the reader/writer lock for namespace access */
+
+ status = acpi_ut_create_rw_lock(&acpi_gbl_namespace_rw_lock);
return_ACPI_STATUS(status);
}
@@ -97,7 +100,8 @@
*
* RETURN: None.
*
- * DESCRIPTION: Delete all of the system mutex objects.
+ * DESCRIPTION: Delete all of the system mutex objects. This includes mutexes,
+ * spin locks, and reader/writer locks.
*
******************************************************************************/
@@ -107,9 +111,8 @@
ACPI_FUNCTION_TRACE(ut_mutex_terminate);
- /*
- * Delete each predefined mutex object
- */
+ /* Delete each predefined mutex object */
+
for (i = 0; i < ACPI_NUM_MUTEX; i++) {
(void)acpi_ut_delete_mutex(i);
}
@@ -118,6 +121,10 @@
acpi_os_delete_lock(acpi_gbl_gpe_lock);
acpi_os_delete_lock(acpi_gbl_hardware_lock);
+
+ /* Delete the reader/writer lock */
+
+ acpi_ut_delete_rw_lock(&acpi_gbl_namespace_rw_lock);
return_VOID;
}