From 10a3b461a258f52b17fb8e35edf3625726eca9a8 Mon Sep 17 00:00:00 2001 From: Bob Moore Date: Thu, 21 May 2009 10:02:34 +0800 Subject: ACPICA: Mutex support: Fix release ordering issue and current sync level Fixes a problem where if multiple mutexes of the same sync level are acquired but then not released in strict opposite order, the current sync level becomes confused and can cause errors. ACPICA BZ 471. http://acpica.org/bugzilla/show_bug.cgi?id=471 Signed-off-by: Bob Moore Signed-off-by: Lin Ming Signed-off-by: Len Brown --- drivers/acpi/acpica/exmutex.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/drivers/acpi/acpica/exmutex.c b/drivers/acpi/acpica/exmutex.c index d7cb030a21f8..77a592aa53c0 100644 --- a/drivers/acpi/acpica/exmutex.c +++ b/drivers/acpi/acpica/exmutex.c @@ -83,6 +83,15 @@ void acpi_ex_unlink_mutex(union acpi_operand_object *obj_desc) if (obj_desc->mutex.prev) { (obj_desc->mutex.prev)->mutex.next = obj_desc->mutex.next; + + /* + * Migrate the previous sync level associated with this mutex to the + * previous mutex on the list so that it may be preserved. This handles + * the case where several mutexes have been acquired at the same level, + * but are not released in opposite order. + */ + (obj_desc->mutex.prev)->mutex.original_sync_level = + obj_desc->mutex.original_sync_level; } else { thread->acquired_mutex_list = obj_desc->mutex.next; } @@ -349,6 +358,7 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc, struct acpi_walk_state *walk_state) { acpi_status status = AE_OK; + u8 previous_sync_level; ACPI_FUNCTION_TRACE(ex_release_mutex); @@ -404,14 +414,21 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc, return_ACPI_STATUS(AE_AML_MUTEX_ORDER); } + /* + * Get the previous sync_level from the head of the acquired mutex list. + * This handles the case where several mutexes at the same level have been + * acquired, but are not released in reverse order. + */ + previous_sync_level = + walk_state->thread->acquired_mutex_list->mutex.original_sync_level; + status = acpi_ex_release_mutex_object(obj_desc); if (obj_desc->mutex.acquisition_depth == 0) { /* Restore the original sync_level */ - walk_state->thread->current_sync_level = - obj_desc->mutex.original_sync_level; + walk_state->thread->current_sync_level = previous_sync_level; } return_ACPI_STATUS(status); } -- cgit v1.2.3