From 246a6c7ab9f72b4e2f51a8ff955624b0aaa1c9af Mon Sep 17 00:00:00 2001
From: khizmax <libcds.dev@gmail.com>
Date: Mon, 24 Apr 2017 22:57:58 +0300
Subject: [PATCH] Fixed uRCU barriers on read-side entry/exit

---
 cds/urcu/details/gp.h | 8 +-------
 cds/urcu/details/sh.h | 9 ++-------
 2 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/cds/urcu/details/gp.h b/cds/urcu/details/gp.h
index eb43fc5f..512a0b2b 100644
--- a/cds/urcu/details/gp.h
+++ b/cds/urcu/details/gp.h
@@ -70,13 +70,7 @@ namespace cds { namespace urcu { namespace details {
             pRec->m_nAccessControl.store( gp_singleton<RCUtag>::instance()->global_control_word(atomics::memory_order_relaxed),
                 atomics::memory_order_relaxed );
 
-#   if CDS_COMPILER == CDS_COMPILER_CLANG && CDS_COMPILER_VERSION < 30800
-            // Seems, CLang 3.6-3.7 cannot handle acquire barrier correctly
-            CDS_COMPILER_RW_BARRIER;
-#   else
-            // acquire barrier
-            pRec->m_nAccessControl.load( atomics::memory_order_acquire );
-#   endif
+            atomics::atomic_thread_fence( atomics::memory_order_seq_cst );
         }
         else {
             // nested lock
diff --git a/cds/urcu/details/sh.h b/cds/urcu/details/sh.h
index f02c37a4..03ae2be6 100644
--- a/cds/urcu/details/sh.h
+++ b/cds/urcu/details/sh.h
@@ -74,13 +74,7 @@ namespace cds { namespace urcu { namespace details {
             pRec->m_nAccessControl.store( sh_singleton<RCUtag>::instance()->global_control_word(atomics::memory_order_relaxed),
                 atomics::memory_order_relaxed );
 
-#   if CDS_COMPILER == CDS_COMPILER_CLANG && CDS_COMPILER_VERSION < 30800
-            // Seems, CLang 3.6-3.7 cannot handle acquire barrier correctly
             CDS_COMPILER_RW_BARRIER;
-#   else
-            // acquire barrier
-            pRec->m_nAccessControl.load( atomics::memory_order_acquire );
-#   endif
         }
         else {
             // nested lock
@@ -97,7 +91,8 @@ namespace cds { namespace urcu { namespace details {
         uint32_t tmp = pRec->m_nAccessControl.load( atomics::memory_order_relaxed );
         assert( ( tmp & rcu_class::c_nNestMask ) > 0 );
 
-        pRec->m_nAccessControl.store( tmp - 1, atomics::memory_order_release );
+        CDS_COMPILER_RW_BARRIER;
+        pRec->m_nAccessControl.store( tmp - 1, atomics::memory_order_relaxed );
     }
 
     template <typename RCUtag>
-- 
2.34.1