score: Rework ask for help requests

Process ask for help requests on the current processor.  This avoids
using inter-processor interrupts to make the system behaviour a bit more
predictable.

Update #4531.

1 files changed, 11 insertions, 18 deletions

diff --git a/cpukit/score/src/schedulersmp.c b/cpukit/score/src/schedulersmp.c
index cc566180b7..3bb2638139 100644
--- a/cpukit/score/src/schedulersmp.c
+++ b/cpukit/score/src/schedulersmp.c
@@ -21,28 +21,21 @@
 
 #include <rtems/score/schedulersmpimpl.h>
 
-void _Scheduler_Request_ask_for_help( Thread_Control *the_thread )
+void _Scheduler_SMP_Remove_ask_for_help_from_processor(
+  Thread_Control  *thread,
+  Per_CPU_Control *cpu
+)
 {
-  ISR_lock_Context scheduler_lock_context;
+  ISR_lock_Context lock_context;
 
-  _Thread_Scheduler_acquire_critical( the_thread, &scheduler_lock_context );
+  _Assert( _ISR_lock_Is_owner( &thread->Scheduler.Lock ) );
 
-  if ( _Chain_Is_node_off_chain( &the_thread->Scheduler.Help_node ) ) {
-    Per_CPU_Control  *cpu;
-    ISR_lock_Context  per_cpu_lock_context;
+  _Per_CPU_Acquire( cpu, &lock_context );
 
-    cpu = _Thread_Get_CPU( the_thread );
-    _Per_CPU_Acquire( cpu, &per_cpu_lock_context );
-
-    _Chain_Append_unprotected(
-      &cpu->Threads_in_need_for_help,
-      &the_thread->Scheduler.Help_node
-    );
-
-    _Per_CPU_Release( cpu, &per_cpu_lock_context );
-
-    _Thread_Dispatch_request( _Per_CPU_Get(), cpu );
+  if ( thread->Scheduler.ask_for_help_cpu == cpu ) {
+    _Chain_Extract_unprotected( &thread->Scheduler.Help_node );
+    thread->Scheduler.ask_for_help_cpu = NULL;
   }
 
-  _Thread_Scheduler_release_critical( the_thread, &scheduler_lock_context );
+  _Per_CPU_Release( cpu, &lock_context );
 }