From: Lv Zheng <zetalog@gmail.com>
Date: Wed, 26 Oct 2016 07:40:12 +0000 (+0800)
Subject: ACPICA: Dispatcher: Fix order issue of method termination
X-Git-Tag: v4.9-rc3~9^2~3
X-Git-Url: http://git.cascardo.eti.br/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=25ccd2429fd0af5b9c2c136c8c593491aeabf162

ACPICA: Dispatcher: Fix order issue of method termination

The last step of the method termination should be the end of the method
serialization. Otherwise, the steps happening after it will face the race
issues that cannot be protected by the method serialization mechanism.

This patch fixes this issue by moving the per-method-object deletion code
prior than the end of the method serialization. Otherwise, the possible
race issues may result in AE_ALREADY_EXISTS error in a parallel
environment.

Fixes: 74f51b80a0c4 (ACPICA: Namespace: Fix dynamic table loading issues)
Reported-and-tested-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

diff --git a/drivers/acpi/acpica/dsmethod.c b/drivers/acpi/acpica/dsmethod.c
index 32e9ddc0cf2b..c4028a8dacd5 100644
--- a/drivers/acpi/acpica/dsmethod.c
+++ b/drivers/acpi/acpica/dsmethod.c
@@ -730,26 +730,6 @@ acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
 
 		acpi_ds_method_data_delete_all(walk_state);
 
-		/*
-		 * If method is serialized, release the mutex and restore the
-		 * current sync level for this thread
-		 */
-		if (method_desc->method.mutex) {
-
-			/* Acquisition Depth handles recursive calls */
-
-			method_desc->method.mutex->mutex.acquisition_depth--;
-			if (!method_desc->method.mutex->mutex.acquisition_depth) {
-				walk_state->thread->current_sync_level =
-				    method_desc->method.mutex->mutex.
-				    original_sync_level;
-
-				acpi_os_release_mutex(method_desc->method.
-						      mutex->mutex.os_mutex);
-				method_desc->method.mutex->mutex.thread_id = 0;
-			}
-		}
-
 		/*
 		 * Delete any namespace objects created anywhere within the
 		 * namespace by the execution of this method. Unless:
@@ -786,6 +766,26 @@ acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
 				    ~ACPI_METHOD_MODIFIED_NAMESPACE;
 			}
 		}
+
+		/*
+		 * If method is serialized, release the mutex and restore the
+		 * current sync level for this thread
+		 */
+		if (method_desc->method.mutex) {
+
+			/* Acquisition Depth handles recursive calls */
+
+			method_desc->method.mutex->mutex.acquisition_depth--;
+			if (!method_desc->method.mutex->mutex.acquisition_depth) {
+				walk_state->thread->current_sync_level =
+				    method_desc->method.mutex->mutex.
+				    original_sync_level;
+
+				acpi_os_release_mutex(method_desc->method.
+						      mutex->mutex.os_mutex);
+				method_desc->method.mutex->mutex.thread_id = 0;
+			}
+		}
 	}
 
 	/* Decrement the thread count on the method */