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Subject[RFC PATCH 1/2] ACPICA: Dispatcher: Ignore SyncLevel for auto-serialization mechanism.
Date
From: Robert Moore <robert.moore@intel.com>

It is reported that the auto-serialization mechanism has broken some
machine. This patch fixes the issues by igoring the SyncLevel
attribute of the marked Method.

References: http://www.spinics.net/lists/linux-acpi/msg49496.html
Reported-by: Valdis Kletnieks <validis.kletnieks@vt.edu>
Reported-by: Sabrina Dubroka <sd@queasysnail.net>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
---
drivers/acpi/acpica/acobject.h | 3 ++-
drivers/acpi/acpica/dsmethod.c | 24 +++++++++++++++++++-----
2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/acpi/acpica/acobject.h b/drivers/acpi/acpica/acobject.h
index 1a4d618..22fb644 100644
--- a/drivers/acpi/acpica/acobject.h
+++ b/drivers/acpi/acpica/acobject.h
@@ -193,7 +193,8 @@ struct acpi_object_method {
#define ACPI_METHOD_INTERNAL_ONLY 0x02 /* Method is implemented internally (_OSI) */
#define ACPI_METHOD_SERIALIZED 0x04 /* Method is serialized */
#define ACPI_METHOD_SERIALIZED_PENDING 0x08 /* Method is to be marked serialized */
-#define ACPI_METHOD_MODIFIED_NAMESPACE 0x10 /* Method modified the namespace */
+#define ACPI_METHOD_IGNORE_SYNC_LEVEL 0x10 /* Method was auto-serialized at table load time */
+#define ACPI_METHOD_MODIFIED_NAMESPACE 0x20 /* Method modified the namespace */

/******************************************************************************
*
diff --git a/drivers/acpi/acpica/dsmethod.c b/drivers/acpi/acpica/dsmethod.c
index 73764c7..3c7f737 100644
--- a/drivers/acpi/acpica/dsmethod.c
+++ b/drivers/acpi/acpica/dsmethod.c
@@ -175,8 +175,15 @@ acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
* At this point, we know we have a Named object opcode.
* Mark the method as serialized. Later code will create a mutex for
* this method to enforce serialization.
+ *
+ * Note, ACPI_METHOD_IGNORE_SYNC_LEVEL flag means that we will ignore the
+ * Sync Level mechanism for this method, even though it is now serialized.
+ * Otherwise, there can be conflicts with existing ASL code that actually
+ * uses sync levels.
*/
- walk_state->method_desc->method.info_flags |= ACPI_METHOD_SERIALIZED;
+ walk_state->method_desc->method.sync_level = 0;
+ walk_state->method_desc->method.info_flags |=
+ (ACPI_METHOD_SERIALIZED | ACPI_METHOD_IGNORE_SYNC_LEVEL);

ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"Method serialized [%4.4s] %p - [%s] (%4.4X)\n",
@@ -349,13 +356,19 @@ acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
/*
* The current_sync_level (per-thread) must be less than or equal to
* the sync level of the method. This mechanism provides some
- * deadlock prevention
+ * deadlock prevention.
+ *
+ * If the method was auto-serialized, we just ignore the sync level
+ * mechanism, because auto-serialization of methods can interfere
+ * with ASL code that actually uses sync levels.
*
* Top-level method invocation has no walk state at this point
*/
if (walk_state &&
- (walk_state->thread->current_sync_level >
- obj_desc->method.mutex->mutex.sync_level)) {
+ (!(obj_desc->method.
+ info_flags & ACPI_METHOD_IGNORE_SYNC_LEVEL))
+ && (walk_state->thread->current_sync_level >
+ obj_desc->method.mutex->mutex.sync_level)) {
ACPI_ERROR((AE_INFO,
"Cannot acquire Mutex for method [%4.4s], current SyncLevel is too large (%u)",
acpi_ut_get_node_name(method_node),
@@ -800,7 +813,8 @@ acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
method_desc->method.info_flags &=
~ACPI_METHOD_SERIALIZED_PENDING;
method_desc->method.info_flags |=
- ACPI_METHOD_SERIALIZED;
+ (ACPI_METHOD_SERIALIZED |
+ ACPI_METHOD_IGNORE_SYNC_LEVEL);
method_desc->method.sync_level = 0;
}

--
1.7.10


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