From 95efa8296b60bd6405d1098f950b269decbddd17 Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Thu, 12 Sep 2019 12:22:42 +0200
Subject: Allocate patches separately.

Avoids accessing stale pointers after realloc.
---
 src/qms.c | 37 ++++++++++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/src/qms.c b/src/qms.c
index d782d0c..c22cc97 100644
--- a/src/qms.c
+++ b/src/qms.c
@@ -84,7 +84,7 @@ typedef struct QMSMGContext {
     int solve_level;
     int boundary_offset;
 
-    CoordPatch *patches;
+    CoordPatch **patches;
     int nb_patches;
 
     /* timings */
@@ -226,6 +226,15 @@ static void get_extents(size_t **pextents, int *level_size, cGH *gh)
 }
 
 static CoordPatch *get_coord_patch(QMSMGContext *ms, int level)
+{
+    for (int i = 0; i < ms->nb_patches; i++)
+        if (ms->patches[i]->level == level)
+            return ms->patches[i];
+
+    return NULL;
+}
+
+static int alloc_coord_patch(QMSMGContext *ms, int level)
 {
     cGH *gh = ms->gh;
 
@@ -252,16 +261,12 @@ static CoordPatch *get_coord_patch(QMSMGContext *ms, int level)
     MG2DContext *solver;
     int i, ret;
 
-    for (int i = 0; i < ms->nb_patches; i++) {
-        cp = &ms->patches[i];
-
-        if (cp->level == level)
-            return cp;
-    }
+    cp = calloc(1, sizeof(*cp));
+    if (!cp)
+        CCTK_WARN(0, "Error allocating patch");
 
-    /* create a new patch */
     ms->patches = realloc(ms->patches, sizeof(*ms->patches) * (ms->nb_patches + 1));
-    cp = &ms->patches[ms->nb_patches];
+    ms->patches[ms->nb_patches] = cp;
 
     memset(cp, 0, sizeof(*cp));
 
@@ -403,15 +408,23 @@ finish:
     free(extents);
 
     ms->nb_patches++;
-    return cp;
+    return 0;
 }
 
-static void coord_patch_free(CoordPatch *cp)
+static void coord_patch_free(CoordPatch **pcp)
 {
+    CoordPatch *cp = *pcp;
+
+    if (!cp)
+        return;
+
     mg2d_solver_free(&cp->solver);
 
     if (cp->solver_comm != MPI_COMM_NULL)
         MPI_Comm_free(&cp->solver_comm);
+
+    free(cp);
+    *pcp = NULL;
 }
 
 static void print_stats(QMSMGContext *ms)
@@ -1593,6 +1606,8 @@ void qms_mg_init(CCTK_ARGUMENTS)
         if (ret < 0)
             CCTK_WARN(0, "Error initializing the solver context");
     }
+
+    alloc_coord_patch(qms_context, reflevel);
 }
 
 void qms_mg_inithist(CCTK_ARGUMENTS)
-- 
cgit v1.2.3