Revert "Recursive lock"

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 38e2ac14084a26442fdafa19581f5843ec1dc897..ecc53580716e26ee1b3134baac8dd4e4b6f38ea3 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1851,25 +1851,10 @@ namespace {
 
       assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
 
-      if (TM.thread_should_stop(threadID))
-      {
-          lock_grab(&(sp->lock));
-          break;
-      }
-
       // New best move?
       if (value > sp->bestValue) // Less then 2% of cases
       {
-          // Recursive locking, lock current split point and its ancestors to
-          // guarantee thread_should_stop() and sp_update_pv() are race free.
-          SplitPoint* spChain[MAX_THREADS * ACTIVE_SPLIT_POINTS_MAX];
-          int cnt = 0;
-          for (spChain[cnt] = sp; spChain[cnt]; )
-          {
-              lock_grab(&(spChain[cnt++]->lock));
-              spChain[cnt] = spChain[cnt - 1]->parent;
-          }
-
+          lock_grab(&(sp->lock));
           if (value > sp->bestValue && !TM.thread_should_stop(threadID))
           {
               sp->bestValue = value;
@@ -1879,10 +1864,7 @@ namespace {
                   sp_update_pv(sp->parentSstack, ss, sp->ply);
               }
           }
-
-          // Release locks in reverse order
-          while (cnt > 0)
-              lock_release(&(spChain[--cnt]->lock));
+          lock_release(&(sp->lock));
       }
     }
 
@@ -1978,25 +1960,10 @@ namespace {
 
       assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
 
-      if (TM.thread_should_stop(threadID))
-      {
-          lock_grab(&(sp->lock));
-          break;
-      }
-
       // New best move?
       if (value > sp->bestValue) // Less then 2% of cases
       {
-          // Recursive locking, lock current split point and its ancestors to
-          // guarantee thread_should_stop() and sp_update_pv() are race free.
-          SplitPoint* spChain[MAX_THREADS * ACTIVE_SPLIT_POINTS_MAX];
-          int cnt = 0;
-          for (spChain[cnt] = sp; spChain[cnt]; )
-          {
-              lock_grab(&(spChain[cnt++]->lock));
-              spChain[cnt] = spChain[cnt - 1]->parent;
-          }
-
+          lock_grab(&(sp->lock));
           if (value > sp->bestValue && !TM.thread_should_stop(threadID))
           {
               sp->bestValue = value;
@@ -2013,10 +1980,7 @@ namespace {
                       ss[sp->ply].mateKiller = move;
               }
           }
-
-          // Release locks in reverse order
-          while (cnt > 0)
-              lock_release(&(spChain[--cnt]->lock));
+          lock_release(&(sp->lock));
       }
     }
 
@@ -2650,6 +2614,8 @@ namespace {
         // If this thread has been assigned work, launch a search
         if (threads[threadID].state == THREAD_WORKISWAITING)
         {
+            assert(!AllThreadsShouldExit);
+
             threads[threadID].state = THREAD_SEARCHING;
 
             if (threads[threadID].splitPoint->pvNode)
@@ -2659,13 +2625,7 @@ namespace {
 
             assert(threads[threadID].state == THREAD_SEARCHING);
 
-            // If this is a slave thread reset to available, instead
-            // if it is a master thread and all slaves have finished
-            // then leave as is to avoid booking by another master,
-            // we will leave idle loop shortly anyhow.
-            if (   !AllThreadsShouldExit
-                && (!waitSp || waitSp->cpus > 0))
-                threads[threadID].state = THREAD_AVAILABLE;
+            threads[threadID].state = THREAD_AVAILABLE;
         }
 
         // If this thread is the master of a split point and all threads have