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/dsinit.c b/drivers/acpi/acpica/dsinit.c
index eb144b1..3aae13f 100644
--- a/drivers/acpi/acpica/dsinit.c
+++ b/drivers/acpi/acpica/dsinit.c
@@ -180,11 +180,23 @@
/* Walk entire namespace from the supplied root */
- status = acpi_walk_namespace(ACPI_TYPE_ANY, start_node, ACPI_UINT32_MAX,
- acpi_ds_init_one_object, &info, NULL);
+ status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
+ if (ACPI_FAILURE(status)) {
+ return_ACPI_STATUS(status);
+ }
+
+ /*
+ * We don't use acpi_walk_namespace since we do not want to acquire
+ * the namespace reader lock.
+ */
+ status =
+ acpi_ns_walk_namespace(ACPI_TYPE_ANY, start_node, ACPI_UINT32_MAX,
+ ACPI_NS_WALK_UNLOCK, acpi_ds_init_one_object,
+ &info, NULL);
if (ACPI_FAILURE(status)) {
ACPI_EXCEPTION((AE_INFO, status, "During WalkNamespace"));
}
+ (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
status = acpi_get_table_by_index(table_index, &table);
if (ACPI_FAILURE(status)) {