rtems: Avoid Giant lock for signals

Update #2555.

4 files changed, 89 insertions, 80 deletions

diff --git a/cpukit/rtems/src/signalcatch.c b/cpukit/rtems/src/signalcatch.c
index 7bf298d1d6..73138a1015 100644
--- a/cpukit/rtems/src/signalcatch.c
+++ b/cpukit/rtems/src/signalcatch.c
@@ -22,8 +22,6 @@
 #include <rtems/rtems/signalimpl.h>
 #include <rtems/rtems/asrimpl.h>
 #include <rtems/rtems/tasks.h>
-#include <rtems/score/isrlevel.h>
-#include <rtems/score/threaddispatch.h>
 #include <rtems/score/threadimpl.h>
 
 void _Signal_Action_handler(
@@ -52,8 +50,9 @@ void _Signal_Action_handler(
   asr = &api->Signal;
   signal_set = _ASR_Get_posted_signals( asr );
 
-  if ( !signal_set ) /* similar to _ASR_Are_signals_pending( asr ) */
+  if ( signal_set == 0 ) {
     return;
+  }
 
   asr->nest_level += 1;
   rtems_task_mode( asr->mode_set, RTEMS_ALL_MODE_MASKS, &prev_mode );
@@ -74,11 +73,12 @@ rtems_status_code rtems_signal_catch(
   ASR_Information    *asr;
   ISR_lock_Context    lock_context;
 
-  executing = _Thread_Get_executing();
-  api = (RTEMS_API_Control*)executing->API_Extensions[ THREAD_API_RTEMS ];
+  _ISR_lock_ISR_disable( &lock_context );
+  executing = _Thread_Executing;
+  api = executing->API_Extensions[ THREAD_API_RTEMS ];
   asr = &api->Signal;
 
-  _ASR_Acquire( asr, &lock_context );
+  _ASR_Acquire_critical( asr, &lock_context );
 
   if ( !_ASR_Is_null_handler( asr_handler ) ) {
     asr->mode_set = mode_set;
diff --git a/cpukit/rtems/src/signalmp.c b/cpukit/rtems/src/signalmp.c
index 8c63c2f790..cd89e9f0dd 100644
--- a/cpukit/rtems/src/signalmp.c
+++ b/cpukit/rtems/src/signalmp.c
@@ -24,13 +24,36 @@
 #include <rtems/score/threadimpl.h>
 #include <rtems/score/threadqimpl.h>
 
+/**
+ *  The following enumerated type defines the list of
+ *  remote signal operations.
+ */
+typedef enum {
+  SIGNAL_MP_SEND_REQUEST  = 0,
+  SIGNAL_MP_SEND_RESPONSE = 1
+}   Signal_MP_Remote_operations;
+
+/**
+ *  The following data structure defines the packet used to perform
+ *  remote signal operations.
+ */
+typedef struct {
+  rtems_packet_prefix          Prefix;
+  Signal_MP_Remote_operations  operation;
+  rtems_signal_set             signal_set;
+}   Signal_MP_Packet;
+
 RTEMS_STATIC_ASSERT(
   sizeof(Signal_MP_Packet) <= MP_PACKET_MINIMUM_PACKET_SIZE,
   Signal_MP_Packet
 );
 
-static Signal_MP_Packet *_Signal_MP_Get_packet( void )
+static Signal_MP_Packet *_Signal_MP_Get_packet( Objects_Id id )
 {
+  if ( !_Thread_MP_Is_remote( id ) ) {
+    return NULL;
+  }
+
   return (Signal_MP_Packet *) _MPCI_Get_packet();
 }
 
@@ -42,43 +65,31 @@ static Signal_MP_Packet *_Signal_MP_Get_packet( void )
  *
  */
 
-rtems_status_code _Signal_MP_Send_request_packet (
-  Signal_MP_Remote_operations operation,
-  Objects_Id                  task_id,
-  rtems_signal_set            signal_in
+rtems_status_code _Signal_MP_Send(
+  rtems_id         id,
+  rtems_signal_set signal_set
 )
 {
   Signal_MP_Packet *the_packet;
 
-  switch ( operation ) {
-
-    case SIGNAL_MP_SEND_REQUEST:
-
-      the_packet                    = _Signal_MP_Get_packet();
-      the_packet->Prefix.the_class  = MP_PACKET_SIGNAL;
-      the_packet->Prefix.length     = sizeof ( Signal_MP_Packet );
-      the_packet->Prefix.to_convert = sizeof ( Signal_MP_Packet );
-      the_packet->operation         = operation;
-      the_packet->Prefix.id         = task_id;
-      the_packet->signal_in         = signal_in;
-
-      return _MPCI_Send_request_packet(
-        _Objects_Get_node( task_id ),
-        &the_packet->Prefix,
-        STATES_READY,  /* Not used */
-        RTEMS_TIMEOUT
-      );
-      break;
-
-    case SIGNAL_MP_SEND_RESPONSE:
-      break;
-
+  the_packet = _Signal_MP_Get_packet( id );
+  if ( the_packet == NULL ) {
+    return RTEMS_INVALID_ID;
   }
-  /*
-   *  The following line is included to satisfy compilers which
-   *  produce warnings when a function does not end with a return.
-   */
-  return RTEMS_INTERNAL_ERROR;
+
+  the_packet->Prefix.the_class  = MP_PACKET_SIGNAL;
+  the_packet->Prefix.length     = sizeof( *the_packet );
+  the_packet->Prefix.to_convert = sizeof( *the_packet );
+  the_packet->operation         = SIGNAL_MP_SEND_REQUEST;
+  the_packet->Prefix.id         = id;
+  the_packet->signal_set        = signal_set;
+
+  return (rtems_status_code) _MPCI_Send_request_packet(
+    _Objects_Get_node( id ),
+    &the_packet->Prefix,
+    STATES_READY,
+    RTEMS_TIMEOUT
+  );
 }
 
 static void _Signal_MP_Send_response_packet (
@@ -127,7 +138,7 @@ void _Signal_MP_Process_packet (
 
       the_packet->Prefix.return_code = rtems_signal_send(
         the_packet->Prefix.id,
-        the_packet->signal_in
+        the_packet->signal_set
       );
 
       _Signal_MP_Send_response_packet(
diff --git a/cpukit/rtems/src/signalsend.c b/cpukit/rtems/src/signalsend.c
index 4153e407f4..162de5c7c8 100644
--- a/cpukit/rtems/src/signalsend.c
+++ b/cpukit/rtems/src/signalsend.c
@@ -21,7 +21,7 @@
 #include <rtems/rtems/signalimpl.h>
 #include <rtems/rtems/asrimpl.h>
 #include <rtems/rtems/tasks.h>
-#include <rtems/score/isr.h>
+#include <rtems/score/threaddispatch.h>
 #include <rtems/score/threadimpl.h>
 
 rtems_status_code rtems_signal_send(
@@ -29,50 +29,48 @@ rtems_status_code rtems_signal_send(
   rtems_signal_set  signal_set
 )
 {
-  Thread_Control          *the_thread;
-  Objects_Locations        location;
-  RTEMS_API_Control       *api;
-  ASR_Information         *asr;
+  Thread_Control    *the_thread;
+  ISR_lock_Context   lock_context;
+  RTEMS_API_Control *api;
+  ASR_Information   *asr;
 
-  if ( !signal_set )
+  if ( signal_set == 0 ) {
     return RTEMS_INVALID_NUMBER;
+  }
 
-  the_thread = _Thread_Get( id, &location );
-  switch ( location ) {
-
-    case OBJECTS_LOCAL:
-      api = the_thread->API_Extensions[ THREAD_API_RTEMS ];
-      asr = &api->Signal;
-
-      if ( ! _ASR_Is_null_handler( asr->handler ) ) {
-        if ( asr->is_enabled ) {
-          _ASR_Post_signals( asr, signal_set, &asr->signals_posted );
-          _Thread_Add_post_switch_action(
-            the_thread,
-            &api->Signal_action,
-            _Signal_Action_handler
-          );
-        } else {
-          _ASR_Post_signals( asr, signal_set, &asr->signals_pending );
-        }
-        _Objects_Put( &the_thread->Object );
-        return RTEMS_SUCCESSFUL;
-      }
-      _Objects_Put( &the_thread->Object );
-      return RTEMS_NOT_DEFINED;
+  the_thread = _Thread_Get_interrupt_disable( id, &lock_context );
 
+  if ( the_thread == NULL ) {
 #if defined(RTEMS_MULTIPROCESSING)
-    case OBJECTS_REMOTE:
-      return _Signal_MP_Send_request_packet(
-        SIGNAL_MP_SEND_REQUEST,
-        id,
-        signal_set
-      );
+    return _Signal_MP_Send( id, signal_set );
+#else
+    return RTEMS_INVALID_ID;
 #endif
+  }
+
+  api = the_thread->API_Extensions[ THREAD_API_RTEMS ];
+  asr = &api->Signal;
+
+  _ASR_Acquire_critical( asr, &lock_context );
+
+  if ( _ASR_Is_null_handler( asr->handler ) ) {
+    _ASR_Release( asr, &lock_context );
+    return RTEMS_NOT_DEFINED;
+  }
 
-    case OBJECTS_ERROR:
-      break;
+  if ( asr->is_enabled ) {
+    _ASR_Post_signals( signal_set, &asr->signals_posted );
+    _ASR_Release( asr, &lock_context );
+    _Thread_Add_post_switch_action(
+      the_thread,
+      &api->Signal_action,
+      _Signal_Action_handler
+    );
+    _Thread_Dispatch();
+  } else {
+    _ASR_Post_signals( signal_set, &asr->signals_pending );
+    _ASR_Release( asr, &lock_context );
   }
 
-  return RTEMS_INVALID_ID;
+  return RTEMS_SUCCESSFUL;
 }
diff --git a/cpukit/rtems/src/taskmode.c b/cpukit/rtems/src/taskmode.c
index 0fc0924993..e2dc7ed9d8 100644
--- a/cpukit/rtems/src/taskmode.c
+++ b/cpukit/rtems/src/taskmode.c
@@ -99,8 +99,8 @@ rtems_status_code rtems_task_mode(
 
     if ( is_asr_enabled != asr->is_enabled ) {
       asr->is_enabled = is_asr_enabled;
-      _ASR_Swap_signals( asr );
-      if ( _ASR_Are_signals_pending( asr ) ) {
+
+      if ( _ASR_Swap_signals( asr ) != 0 ) {
         needs_asr_dispatching = true;
         _Thread_Add_post_switch_action(
           executing,