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/acglobal.h b/drivers/acpi/acpica/acglobal.h
index f3e87ba..f431b99 100644
--- a/drivers/acpi/acpica/acglobal.h
+++ b/drivers/acpi/acpica/acglobal.h
@@ -165,6 +165,10 @@
ACPI_EXTERN u8 acpi_gbl_integer_byte_width;
ACPI_EXTERN u8 acpi_gbl_integer_nybble_width;
+/* Reader/Writer lock is used for namespace walk and dynamic table unload */
+
+ACPI_EXTERN struct acpi_rw_lock acpi_gbl_namespace_rw_lock;
+
/*****************************************************************************
*
* Mutual exlusion within ACPICA subsystem