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/tbinstal.c b/drivers/acpi/acpica/tbinstal.c
index c379930..f865d5a 100644
--- a/drivers/acpi/acpica/tbinstal.c
+++ b/drivers/acpi/acpica/tbinstal.c
@@ -434,27 +434,56 @@
*
* PARAMETERS: table_index - Table index
*
- * RETURN: None
+ * RETURN: Status
*
* DESCRIPTION: Delete all namespace objects created when this table was loaded.
*
******************************************************************************/
-void acpi_tb_delete_namespace_by_owner(u32 table_index)
+acpi_status acpi_tb_delete_namespace_by_owner(u32 table_index)
{
acpi_owner_id owner_id;
+ acpi_status status;
- (void)acpi_ut_acquire_mutex(ACPI_MTX_TABLES);
- if (table_index < acpi_gbl_root_table_list.count) {
- owner_id =
- acpi_gbl_root_table_list.tables[table_index].owner_id;
- } else {
- (void)acpi_ut_release_mutex(ACPI_MTX_TABLES);
- return;
+ ACPI_FUNCTION_TRACE(tb_delete_namespace_by_owner);
+
+ status = acpi_ut_acquire_mutex(ACPI_MTX_TABLES);
+ if (ACPI_FAILURE(status)) {
+ return_ACPI_STATUS(status);
}
+ if (table_index >= acpi_gbl_root_table_list.count) {
+
+ /* The table index does not exist */
+
+ (void)acpi_ut_release_mutex(ACPI_MTX_TABLES);
+ return_ACPI_STATUS(AE_NOT_EXIST);
+ }
+
+ /* Get the owner ID for this table, used to delete namespace nodes */
+
+ owner_id = acpi_gbl_root_table_list.tables[table_index].owner_id;
(void)acpi_ut_release_mutex(ACPI_MTX_TABLES);
+
+ /*
+ * Need to acquire the namespace writer lock to prevent interference
+ * with any concurrent namespace walks. The interpreter must be
+ * released during the deletion since the acquisition of the deletion
+ * lock may block, and also since the execution of a namespace walk
+ * must be allowed to use the interpreter.
+ */
+ acpi_ut_release_mutex(ACPI_MTX_INTERPRETER);
+ status = acpi_ut_acquire_write_lock(&acpi_gbl_namespace_rw_lock);
+
acpi_ns_delete_namespace_by_owner(owner_id);
+ if (ACPI_FAILURE(status)) {
+ return_ACPI_STATUS(status);
+ }
+
+ acpi_ut_release_write_lock(&acpi_gbl_namespace_rw_lock);
+
+ status = acpi_ut_acquire_mutex(ACPI_MTX_INTERPRETER);
+ return_ACPI_STATUS(status);
}
/*******************************************************************************