Revert "Resolve deadlock conditions in deferred work queue."

This reverts commit aaadc0e5955551542ddc5fc84cc54dd32f8d9788.

Change-Id: Ia92dcb307efbacea6a7afbee00b1e881f995cfa2
Reviewed-on: http://gfw160.aus.stglabs.ibm.com:8080/gerrit/12181
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>
Tested-by: Daniel M. Crowell <dcrowell@us.ibm.com>

1 files changed, 5 insertions, 18 deletions

diff --git a/src/kernel/deferred.C b/src/kernel/deferred.C
index 2e77a125d..ffa16d742 100644
--- a/src/kernel/deferred.C
+++ b/src/kernel/deferred.C
@@ -31,20 +31,10 @@
     reinterpret_cast<DeferredWork*>((item)->iv_cpus_and_next & 0xFFFFFFFF)
 
 /** Set the DeferredWork pointer part of a iv_cpus_and_next instance var. */
-#define DEFERRED_QUEUE_SET_NEXT_PTR(tail,item) \
-    { \
-        uint64_t old_value = 0; \
-        uint64_t new_value = 0; \
-        do \
-        { \
-            old_value = (tail)->iv_cpus_and_next; \
-            new_value = (old_value & 0xFFFFFFFF00000000ull) | \
-                        reinterpret_cast<uint64_t>(item); \
-        } \
-        while (!__sync_bool_compare_and_swap(&(tail)->iv_cpus_and_next, \
-                                             old_value, \
-                                             new_value)); \
-    }
+#define DEFERRED_QUEUE_SET_NEXT_PTR(item) \
+    (item)->iv_cpus_and_next = \
+            ((item)->iv_cpus_and_next & 0xFFFFFFFF00000000ull) | \
+            reinterpret_cast<uint64_t>(item)
 
 /** Extract the CPU count portion of a iv_cpus_and_next instance var. */
 #define DEFERRED_QUEUE_GET_CPU_COUNT(item) (item)->iv_cpus_and_next >> 32
@@ -89,7 +79,7 @@ void DeferredQueue::_insert(DeferredWork* i_work)
         }
 
         // Add work item to the end of the list.
-        DEFERRED_QUEUE_SET_NEXT_PTR(tail, i_work);
+        DEFERRED_QUEUE_SET_NEXT_PTR(i_work);
     }
 
     lock.unlock();
@@ -135,9 +125,6 @@ void DeferredQueue::_complete(DeferredWork* i_work)
         old_ptr = iv_cpus_and_next;
     } while(!__sync_bool_compare_and_swap(&iv_cpus_and_next, old_ptr, new_ptr));
 
-    // Clean up our own queue pointer.
-    DEFERRED_QUEUE_SET_NEXT_PTR(i_work, (DeferredWork*)NULL);
-
     // Get the CPU count from the old object pointer and wait until those
     // CPUs get into i_work.
     old_ptr >>= 32;