ACPICA: fix AML mutex re-entrancy

ACPI AML supports "serialized" methods which are protected
by an implicit mutex.  The mutex is re-entrant for that AML thread
to allow recursion.

However, Linux implements notify() by creating a new AML thread.
So for systems where notify() re-enters a serialized method,
deadlock results.

The fix is to use the Linux thread_id as the key to allowing
re-entrancy, not the AML thread pointer.

http://bugzilla.kernel.org/show_bug.cgi?id=5534

Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 17 insertions, 21 deletions

diff --git a/drivers/acpi/executer/exdump.c b/drivers/acpi/executer/exdump.c
index 68d283fd60e7..1a73c14df2c5 100644
--- a/drivers/acpi/executer/exdump.c
+++ b/drivers/acpi/executer/exdump.c
@@ -134,7 +134,7 @@ static struct acpi_exdump_info acpi_ex_dump_method[8] = {
 static struct acpi_exdump_info acpi_ex_dump_mutex[5] = {
         {ACPI_EXD_INIT, ACPI_EXD_TABLE_SIZE(acpi_ex_dump_mutex), NULL},
         {ACPI_EXD_UINT8, ACPI_EXD_OFFSET(mutex.sync_level), "Sync Level"},
-        {ACPI_EXD_POINTER, ACPI_EXD_OFFSET(mutex.owner_thread), "Owner Thread"},
+        {ACPI_EXD_POINTER, ACPI_EXD_OFFSET(mutex.owner_thread_id), "Owner Thread"},
         {ACPI_EXD_UINT16, ACPI_EXD_OFFSET(mutex.acquisition_depth),
          "Acquire Depth"},
         {ACPI_EXD_POINTER, ACPI_EXD_OFFSET(mutex.os_mutex), "OsMutex"}
diff --git a/drivers/acpi/executer/exmutex.c b/drivers/acpi/executer/exmutex.c
index 5101bad5baf8..4eb883bda6ae 100644
--- a/drivers/acpi/executer/exmutex.c
+++ b/drivers/acpi/executer/exmutex.c
@@ -66,10 +66,9 @@ acpi_ex_link_mutex(union acpi_operand_object *obj_desc,
  *
  ******************************************************************************/
 
-void acpi_ex_unlink_mutex(union acpi_operand_object *obj_desc)
+void acpi_ex_unlink_mutex(union acpi_operand_object *obj_desc,
+                          struct acpi_thread_state *thread)
 {
-        struct acpi_thread_state *thread = obj_desc->mutex.owner_thread;
-
         if (!thread) {
                 return;
         }
@@ -174,16 +173,13 @@ acpi_ex_acquire_mutex(union acpi_operand_object *time_desc,
 
         /* Support for multiple acquires by the owning thread */
 
-        if (obj_desc->mutex.owner_thread) {
-                if (obj_desc->mutex.owner_thread->thread_id ==
-                    walk_state->thread->thread_id) {
-                        /*
-                         * The mutex is already owned by this thread, just increment the
-                         * acquisition depth
-                         */
-                        obj_desc->mutex.acquisition_depth++;
-                        return_ACPI_STATUS(AE_OK);
-                }
+        if (obj_desc->mutex.owner_thread_id == acpi_os_get_thread_id()) {
+                /*
+                 * The mutex is already owned by this thread, just increment the
+                 * acquisition depth
+                 */
+                obj_desc->mutex.acquisition_depth++;
+                return_ACPI_STATUS(AE_OK);
         }
 
         /* Acquire the mutex, wait if necessary. Special case for Global Lock */
@@ -206,7 +202,7 @@ acpi_ex_acquire_mutex(union acpi_operand_object *time_desc,
 
         /* Have the mutex: update mutex and walk info and save the sync_level */
 
-        obj_desc->mutex.owner_thread = walk_state->thread;
+        obj_desc->mutex.owner_thread_id = acpi_os_get_thread_id();
         obj_desc->mutex.acquisition_depth = 1;
         obj_desc->mutex.original_sync_level =
             walk_state->thread->current_sync_level;
@@ -246,7 +242,7 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
 
         /* The mutex must have been previously acquired in order to release it */
 
-        if (!obj_desc->mutex.owner_thread) {
+        if (!obj_desc->mutex.owner_thread_id) {
                 ACPI_ERROR((AE_INFO,
                             "Cannot release Mutex [%4.4s], not acquired",
                             acpi_ut_get_node_name(obj_desc->mutex.node)));
@@ -266,14 +262,14 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
          * The Mutex is owned, but this thread must be the owner.
          * Special case for Global Lock, any thread can release
          */
-        if ((obj_desc->mutex.owner_thread->thread_id !=
+        if ((obj_desc->mutex.owner_thread_id !=
              walk_state->thread->thread_id)
             && (obj_desc->mutex.os_mutex != acpi_gbl_global_lock_mutex)) {
                 ACPI_ERROR((AE_INFO,
                             "Thread %lX cannot release Mutex [%4.4s] acquired by thread %lX",
                             (unsigned long)walk_state->thread->thread_id,
                             acpi_ut_get_node_name(obj_desc->mutex.node),
-                            (unsigned long)obj_desc->mutex.owner_thread->thread_id));
+                            (unsigned long)obj_desc->mutex.owner_thread_id));
                 return_ACPI_STATUS(AE_AML_NOT_OWNER);
         }
 
@@ -300,7 +296,7 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
 
         /* Unlink the mutex from the owner's list */
 
-        acpi_ex_unlink_mutex(obj_desc);
+        acpi_ex_unlink_mutex(obj_desc, walk_state->thread);
 
         /* Release the mutex, special case for Global Lock */
 
@@ -312,7 +308,7 @@ acpi_ex_release_mutex(union acpi_operand_object *obj_desc,
 
         /* Update the mutex and restore sync_level */
 
-        obj_desc->mutex.owner_thread = NULL;
+        obj_desc->mutex.owner_thread_id = ACPI_MUTEX_NOT_ACQUIRED;
         walk_state->thread->current_sync_level =
             obj_desc->mutex.original_sync_level;
 
@@ -367,7 +363,7 @@ void acpi_ex_release_all_mutexes(struct acpi_thread_state *thread)
 
                 /* Mark mutex unowned */
 
-                obj_desc->mutex.owner_thread = NULL;
+                obj_desc->mutex.owner_thread_id = ACPI_MUTEX_NOT_ACQUIRED;
 
                 /* Update Thread sync_level (Last mutex is the important one) */