File mvapich2-openpa-add-memory-barriers.patch of Package mvapich2

commit 68c4106b2a8d8fdb9ba4e2bab90e90e3392b6bbd
Author: Nicolas Morey <nmorey@suse.com>
Date:   Thu Oct 26 12:39:20 2023 +0200

    mvapich2: openpa: add memory barriers
    
    Backport from openPA:
    commit 28d602b620b5d7ec8ca1a7f3ad8ab27d439b1751
    Author: Neil Fortner <nfortne2@hdfgroup.org>
    Date:   Wed Dec 19 13:14:57 2012 -0600
    
        Add more memory barriers to LL/SC ABA tests.  This should fix the recent errors
        on POWER7.
    
        Reviewed by goodell.
    
    Signed-off-by: Nicolas Morey <nmorey@suse.com>

diff --git src/openpa/test/test_primitives.c src/openpa/test/test_primitives.c
index a83b95e00578..4533c643d581 100644
--- src/openpa/test/test_primitives.c
+++ src/openpa/test/test_primitives.c
@@ -3783,12 +3783,18 @@ static int threaded_llsc_int_aba_helper_0(llsc_int_aba_t *udata)
             nerrors++;
         } /* end if */
 
+        /* Make sure shared_val is initialized before passing point 0 */
+        OPA_write_barrier();
+
         /* Point 0 */
         OPA_store_int(&udata->pass_point_0, 1);
 
         /* Wait until thread 1 passes point 1 */
         while(!OPA_load_int(&udata->pass_point_1));
 
+        /* Make sure that change_val is loaded after passing point 1 */
+        OPA_read_barrier();
+
         /* Store conditional 1 to the shared value */
         if(OPA_SC_int(&udata->shared_val, 1)) {
             /* SC succeeded, make sure that the shared value was not changed by
@@ -3870,12 +3876,12 @@ static void *threaded_llsc_int_aba_helper_1(void *_udata)
              * of this test */
             OPA_store_int(&udata->shared_val, 1);
             OPA_store_int(&udata->shared_val, 0);
-
-            /* Write barrier to make sure the shared value was actually updated
-             * before we mark point 1 as passed */
-            OPA_write_barrier();
         } /* end if */
 
+        /* Write barrier to make sure the shared_val (if appropriate) and
+         * change_val are actually updated before we mark point 1 as passed */
+        OPA_write_barrier();
+
         /* Point 1 */
         OPA_store_int(&udata->pass_point_1, 1);
 
@@ -4012,12 +4018,18 @@ static int threaded_llsc_ptr_aba_helper_0(llsc_ptr_aba_t *udata)
             nerrors++;
         } /* end if */
 
+        /* Make sure shared_val is initialized before passing point 0 */
+        OPA_write_barrier();
+
         /* Point 0 */
         OPA_store_int(&udata->pass_point_0, 1);
 
         /* Wait until thread 1 passes point 1 */
         while(!OPA_load_int(&udata->pass_point_1));
 
+        /* Make sure that change_val is loaded after passing point 1 */
+        OPA_read_barrier();
+
         /* Store conditional 1 to the shared value */
         if(OPA_SC_ptr(&udata->shared_val, (void *) ((int *) 0 + 1))) {
             /* SC succeeded, make sure that the shared value was not changed by
@@ -4099,12 +4111,12 @@ static void *threaded_llsc_ptr_aba_helper_1(void *_udata)
              * of this test */
             OPA_store_ptr(&udata->shared_val, (void *) ((int *) 0 + 1));
             OPA_store_ptr(&udata->shared_val, (void *) 0);
-
-            /* Write barrier to make sure the shared value was actually updated
-             * before we mark point 1 as passed */
-            OPA_write_barrier();
         } /* end if */
 
+        /* Write barrier to make sure the shared_val (if appropriate) and
+         * change_val are actually updated before we mark point 1 as passed */
+        OPA_write_barrier();
+
         /* Point 1 */
         OPA_store_int(&udata->pass_point_1, 1);