star-enclosures-2d

commit 31f5a4c86245f4c9446190fd7a2f71fe4a57014a
parent b3fa344203d933d15e6e28dd09d244b066b86474
Author: Christophe Coustet <christophe.coustet@meso-star.com>
Date:   Fri, 20 Apr 2018 14:40:46 +0200

 BugFix: possible omp runtime error.

Race condition could lead to some threads not involved in some omp constructs.

Diffstat:
M
src/senc2d_scene_analyze.c
 | 
64
++++++++++++++++++++++++++++++++++------------------------------

1 file changed, 34 insertions(+), 30 deletions(-)
diff --git a/src/senc2d_scene_analyze.c b/src/senc2d_scene_analyze.c
@@ -510,11 +510,11 @@ extract_connex_components
     if(s2d_scn) S2D(scene_ref_put(s2d_scn));
     if(s2d_shp) S2D(shape_ref_put(s2d_shp));
   }
-  if(*res != RES_OK) return;
 
 #ifndef NDEBUG
   /* Need to wait for all threads done to be able to check stuff */
   #pragma omp barrier
+  if(*res != RES_OK) return;
   #pragma omp single
   {
     ASSERT(*component_count ==
@@ -1077,6 +1077,7 @@ senc2d_scene_analyze
   /* Used as args to have shared vars between threads in functions */
   struct cc_descriptor* infinity_first_cc = NULL;
   res_T res = RES_OK;
+  res_T res2 = RES_OK;
 
   if(!scn || !out_desc) return RES_BAD_ARG;
 
@@ -1118,15 +1119,6 @@ senc2d_scene_analyze
      * released / data produced by step 1 cannot be used
      * until next sync point */
 
-    if(res != RES_OK) {
-      #pragma omp single nowait
-      {
-        log_err(scn->dev,
-          "%s: could not build neighbourhoods from scene.\n", FUNC_NAME);
-      } /* No barrier here */
-    }
-    if(res != RES_OK) goto error_;
-
     /* The first thread here allocates some data.
      * Barrier needed at the end to ensure data created before any use. */
     #pragma omp single
@@ -1142,10 +1134,22 @@ senc2d_scene_analyze
       segments_comp_initialized = 1;
       OK2(darray_segment_comp_resize(&segments_comp, scn->nusegs));
     tmp_error:
-      if(tmp_res != RES_OK) res = tmp_res;
+      if(tmp_res != RES_OK) res2 = tmp_res;
     }
     /* Implicit barrier here: constraints on step 1 data are now met */
-    if(res != RES_OK) goto error_;
+
+    if(res != RES_OK || res2 != RES_OK) {
+    #pragma omp single nowait
+      {
+        if(res != RES_OK) {
+          log_err(scn->dev,
+            "%s: could not build neighbourhoods from scene.\n", FUNC_NAME);
+        } else {
+          res = res2;
+        }
+      }
+      goto error_;
+    }
 
     /* One thread releases some data before going to step 2,
      * the others go to step 2 without sync */
@@ -1162,17 +1166,17 @@ senc2d_scene_analyze
      * released / data produced by step 2 cannot be used
      * until next sync point */
 
+    #pragma omp barrier
+    /* Constraints on step 2 data are now met */
+
     if(res != RES_OK) {
       #pragma omp single nowait
       {
         log_err(scn->dev,
           "%s: could not extract connex components from scene.\n", FUNC_NAME);
       } /* No barrier here */
+      goto error_;
     }
-    if(res != RES_OK) goto error_;
-
-    #pragma omp barrier
-    /* Constraints on step 2 data are now met */
 
     /* One thread releases some data before going to step 3,
      * the others go to step 3 without sync */
@@ -1188,6 +1192,15 @@ senc2d_scene_analyze
     /* Barrier at the end of step 3: data used in step 3 can be released /
      * data produced by step 3 can be used */
 
+    if(res != RES_OK) {
+      #pragma omp single nowait
+      {
+        log_err(scn->dev,
+          "%s: could not group connex components from scene.\n", FUNC_NAME);
+      }
+      goto error_;
+    }
+
     /* One thread releases some data before going to step 4,
      * the others go to step 4 without sync */
     #pragma omp single nowait
@@ -1196,31 +1209,22 @@ senc2d_scene_analyze
       s2d_view = NULL;
     } /* No barrier here */
 
-    if(res != RES_OK) {
-      #pragma omp single nowait
-      {
-        log_err(scn->dev,
-          "%s: could not group connex components from scene.\n", FUNC_NAME);
-      } /* No barrier here */
-    }
-    if(res != RES_OK) goto error_;
-
     /* Step 4: Build result */
     build_result(desc, &connex_components, &segments_comp, &res);
     /* No barrier at the end of step 4: data used in step 4 cannot be
      * released / data produced by step 4 cannot be used
      * until next sync point */
 
+    #pragma omp barrier
+     /* Constraints on step 4 data are now met */
+
     if(res != RES_OK) {
       #pragma omp single nowait
       {
         log_err(scn->dev, "%s: could not build result.\n", FUNC_NAME);
-      } /* No barrier here */
+      }
+      goto error_;
     }
-    if(res != RES_OK) goto error_;
-
-    #pragma omp barrier
-    /* Constraints on step 4 data are now met */
 
     /* Some threads release data */
     #pragma omp sections nowait