From f27383a518836881b7b9b88e88d2e31d5b23d048 Mon Sep 17 00:00:00 2001
From: Sebastian Huber <sebastian.huber@embedded-brains.de>
Date: Wed, 20 Apr 2016 14:01:02 +0200
Subject: score: Avoid Giant lock for barriers

Use _Thread_queue_Flush_critical() to atomically release the barrier.

Update #2555.
---
 cpukit/score/src/corebarrierrelease.c | 36 +++++++++---------------
 cpukit/score/src/corebarrierwait.c    | 53 ++++++++++++++++++-----------------
 2 files changed, 40 insertions(+), 49 deletions(-)

(limited to 'cpukit/score/src')

diff --git a/cpukit/score/src/corebarrierrelease.c b/cpukit/score/src/corebarrierrelease.c
index 6d72203e7e..e6ef335abc 100644
--- a/cpukit/score/src/corebarrierrelease.c
+++ b/cpukit/score/src/corebarrierrelease.c
@@ -20,34 +20,24 @@
 #endif
 
 #include <rtems/score/corebarrierimpl.h>
-#include <rtems/score/objectimpl.h>
-#include <rtems/score/threadqimpl.h>
 
 uint32_t _CORE_barrier_Do_surrender(
-  CORE_barrier_Control    *the_barrier
+  CORE_barrier_Control      *the_barrier,
+  Thread_queue_Flush_filter  filter,
 #if defined(RTEMS_MULTIPROCESSING)
-  ,
-  Thread_queue_MP_callout  mp_callout,
-  Objects_Id               mp_id
+  Thread_queue_MP_callout    mp_callout,
+  Objects_Id                 mp_id,
 #endif
+  ISR_lock_Context          *lock_context
 )
 {
-  Thread_Control *the_thread;
-  uint32_t        count;
-
-  count = 0;
-  while (
-    (
-      the_thread = _Thread_queue_Dequeue(
-        &the_barrier->Wait_queue,
-        CORE_BARRIER_TQ_OPERATIONS,
-        mp_callout,
-        mp_id
-      )
-    )
-  ) {
-    count++;
-  }
   the_barrier->number_of_waiting_threads = 0;
-  return count;
+  return _Thread_queue_Flush_critical(
+    &the_barrier->Wait_queue.Queue,
+    CORE_BARRIER_TQ_OPERATIONS,
+    filter,
+    mp_callout,
+    mp_id,
+    lock_context
+  );
 }
diff --git a/cpukit/score/src/corebarrierwait.c b/cpukit/score/src/corebarrierwait.c
index 11495e5e69..4a924b28dd 100644
--- a/cpukit/score/src/corebarrierwait.c
+++ b/cpukit/score/src/corebarrierwait.c
@@ -19,44 +19,45 @@
 #endif
 
 #include <rtems/score/corebarrierimpl.h>
-#include <rtems/score/isrlevel.h>
 #include <rtems/score/statesimpl.h>
-#include <rtems/score/threadqimpl.h>
 
 void _CORE_barrier_Do_seize(
   CORE_barrier_Control    *the_barrier,
   Thread_Control          *executing,
   bool                     wait,
-  Watchdog_Interval        timeout
+  Watchdog_Interval        timeout,
 #if defined(RTEMS_MULTIPROCESSING)
-  ,
   Thread_queue_MP_callout  mp_callout,
-  Objects_Id               mp_id
+  Objects_Id               mp_id,
 #endif
+  ISR_lock_Context        *lock_context
 )
 {
-  ISR_lock_Context lock_context;
+  uint32_t number_of_waiting_threads;
 
   executing->Wait.return_code = CORE_BARRIER_STATUS_SUCCESSFUL;
-  _Thread_queue_Acquire( &the_barrier->Wait_queue, &lock_context );
-  the_barrier->number_of_waiting_threads++;
-  if ( _CORE_barrier_Is_automatic( &the_barrier->Attributes ) ) {
-    if ( the_barrier->number_of_waiting_threads ==
-	 the_barrier->Attributes.maximum_count) {
-      executing->Wait.return_code = CORE_BARRIER_STATUS_AUTOMATICALLY_RELEASED;
-      _Thread_queue_Release( &the_barrier->Wait_queue, &lock_context );
-      _CORE_barrier_Surrender( the_barrier, mp_callout, mp_id );
-      return;
-    }
-  }
 
-  _Thread_queue_Enqueue_critical(
-    &the_barrier->Wait_queue.Queue,
-    CORE_BARRIER_TQ_OPERATIONS,
-    executing,
-    STATES_WAITING_FOR_BARRIER,
-    timeout,
-    CORE_BARRIER_TIMEOUT,
-    &lock_context
-  );
+  _CORE_barrier_Acquire_critical( the_barrier, lock_context );
+
+  number_of_waiting_threads = the_barrier->number_of_waiting_threads;
+  ++number_of_waiting_threads;
+
+  if (
+    _CORE_barrier_Is_automatic( &the_barrier->Attributes )
+      && number_of_waiting_threads == the_barrier->Attributes.maximum_count
+  ) {
+    executing->Wait.return_code = CORE_BARRIER_STATUS_AUTOMATICALLY_RELEASED;
+    _CORE_barrier_Surrender( the_barrier, mp_callout, mp_id, lock_context );
+  } else {
+    the_barrier->number_of_waiting_threads = number_of_waiting_threads;
+    _Thread_queue_Enqueue_critical(
+      &the_barrier->Wait_queue.Queue,
+      CORE_BARRIER_TQ_OPERATIONS,
+      executing,
+      STATES_WAITING_FOR_BARRIER,
+      timeout,
+      CORE_BARRIER_TIMEOUT,
+      lock_context
+    );
+  }
 }
-- 
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