[PATCH 2/2] rtems: Fix task restart within interrupt context

[Sebastian Huber]

rtems_task_restart() may be called from within interrupt context.  So
checking only that the thread to restart is equal to the executing
thread is insufficient to determine a self restart.  We have to also
check that no ISR is in progress.  Merge _Thread_Restart_other() and
_Thread_Restart_self() into one _Thread_Restart() since they share a lot
of common code.

Close #4412.
---
 cpukit/include/rtems/score/threadimpl.h | 15 +-----
 cpukit/rtems/src/taskrestart.c          |  8 +--
 cpukit/score/src/threadrestart.c        | 68 ++++++-------------------
 3 files changed, 17 insertions(+), 74 deletions(-)

diff --git a/cpukit/include/rtems/score/threadimpl.h b/cpukit/include/rtems/score/threadimpl.h
index 8674a3f2b3..44785cd937 100644
--- a/cpukit/include/rtems/score/threadimpl.h
+++ b/cpukit/include/rtems/score/threadimpl.h
@@ -270,19 +270,6 @@ Status_Control _Thread_Start(
   ISR_lock_Context               *lock_context
 );
 
-/**
- * @brief Restarts the currently executing thread.
- *
- * @param[in, out] executing The currently executing thread.
- * @param entry The start entry information for @a executing.
- * @param lock_context The lock context.
- */
-RTEMS_NO_RETURN void _Thread_Restart_self(
-  Thread_Control                 *executing,
-  const Thread_Entry_information *entry,
-  ISR_lock_Context               *lock_context
-);
-
 /**
  * @brief Restarts the thread.
  *
@@ -296,7 +283,7 @@ RTEMS_NO_RETURN void _Thread_Restart_self(
  *
  * @retval STATUS_INCORRECT_STATE The thread was dormant.
  */
-Status_Control _Thread_Restart_other(
+Status_Control _Thread_Restart(
   Thread_Control                 *the_thread,
   const Thread_Entry_information *entry,
   ISR_lock_Context               *lock_context
diff --git a/cpukit/rtems/src/taskrestart.c b/cpukit/rtems/src/taskrestart.c
index 00b0635cef..6bf7358384 100644
--- a/cpukit/rtems/src/taskrestart.c
+++ b/cpukit/rtems/src/taskrestart.c
@@ -48,13 +48,7 @@ rtems_status_code rtems_task_restart(
 
   entry = the_thread->Start.Entry;
   entry.Kinds.Numeric.argument = argument;
-
-  if ( the_thread == _Thread_Executing ) {
-    _Thread_Restart_self( the_thread, &entry, &lock_context );
-    RTEMS_UNREACHABLE();
-  }
-
-  status = _Thread_Restart_other( the_thread, &entry, &lock_context );
+  status = _Thread_Restart( the_thread, &entry, &lock_context );
 
   return _Status_Get( status );
 }
diff --git a/cpukit/score/src/threadrestart.c b/cpukit/score/src/threadrestart.c
index d99c14afc0..7b8c481b80 100644
--- a/cpukit/score/src/threadrestart.c
+++ b/cpukit/score/src/threadrestart.c
@@ -5,8 +5,7 @@
  *
  * @brief This source file contains the implementation of _Thread_Cancel(),
  *   _Thread_Change_life(), _Thread_Close(), _Thread_Exit(), _Thread_Join(),
- *   _Thread_Kill_zombies(), _Thread_Restart_other(), _Thread_Restart_self(),
- *   and _Thread_Set_life_protection().
+ *   _Thread_Kill_zombies(), _Thread_Restart(), and _Thread_Set_life_protection().
  */
 
 /*
@@ -517,7 +516,7 @@ void _Thread_Exit(
   _Thread_State_release( executing, &lock_context );
 }
 
-Status_Control _Thread_Restart_other(
+Status_Control _Thread_Restart(
   Thread_Control                 *the_thread,
   const Thread_Entry_information *entry,
   ISR_lock_Context               *lock_context
@@ -525,6 +524,7 @@ Status_Control _Thread_Restart_other(
 {
   Thread_Life_state    previous;
   Per_CPU_Control     *cpu_self;
+  Thread_Life_state    ignore;
   Thread_queue_Context queue_context;
 
   _Thread_State_acquire_critical( the_thread, lock_context );
@@ -534,16 +534,25 @@ Status_Control _Thread_Restart_other(
     return STATUS_INCORRECT_STATE;
   }
 
+  cpu_self = _Thread_Dispatch_disable_critical( lock_context );
+
+  if (
+    the_thread == _Per_CPU_Get_executing( cpu_self ) &&
+    !_ISR_Is_in_progress()
+  ) {
+    ignore = THREAD_LIFE_PROTECTED | THREAD_LIFE_CHANGE_DEFERRED;
+  } else {
+    ignore = 0;
+  }
+
   the_thread->Start.Entry = *entry;
   previous = _Thread_Change_life_locked(
     the_thread,
     0,
     THREAD_LIFE_RESTARTING,
-    0
+    ignore
   );
 
-  cpu_self = _Thread_Dispatch_disable_critical( lock_context );
-
   if ( _Thread_Is_life_change_allowed( previous ) ) {
     _Thread_Add_life_change_request( the_thread );
     _Thread_State_release( the_thread, lock_context );
@@ -573,53 +582,6 @@ Status_Control _Thread_Restart_other(
   return STATUS_SUCCESSFUL;
 }
 
-void _Thread_Restart_self(
-  Thread_Control                 *executing,
-  const Thread_Entry_information *entry,
-  ISR_lock_Context               *lock_context
-)
-{
-  Per_CPU_Control      *cpu_self;
-  Thread_queue_Context  queue_context;
-
-  _Assert(
-    _Watchdog_Get_state( &executing->Timer.Watchdog ) == WATCHDOG_INACTIVE
-  );
-  _Assert(
-    executing->current_state == STATES_READY
-      || executing->current_state == STATES_SUSPENDED
-  );
-
-  _Thread_queue_Context_initialize( &queue_context );
-  _Thread_queue_Context_clear_priority_updates( &queue_context );
-  _Thread_State_acquire_critical( executing, lock_context );
-
-  executing->Start.Entry = *entry;
-  _Thread_Change_life_locked(
-    executing,
-    0,
-    THREAD_LIFE_RESTARTING,
-    THREAD_LIFE_PROTECTED | THREAD_LIFE_CHANGE_DEFERRED
-  );
-
-  cpu_self = _Thread_Dispatch_disable_critical( lock_context );
-  _Thread_State_release( executing, lock_context );
-
-  _Thread_Wait_acquire_default( executing, lock_context );
-  _Thread_Priority_change(
-    executing,
-    &executing->Real_priority,
-    executing->Start.initial_priority,
-    false,
-    &queue_context
-  );
-  _Thread_Wait_release_default( executing, lock_context );
-
-  _Thread_Priority_update( &queue_context );
-  _Thread_Dispatch_direct_no_return( cpu_self );
-  RTEMS_UNREACHABLE();
-}
-
 Thread_Life_state _Thread_Change_life(
   Thread_Life_state clear,
   Thread_Life_state set,
-- 
2.26.2