Address Robert's feedback

*** 209,233 ****
  
          res = sysdemangle(name + prefixlen, dmp->dm_lang, &mdb_dem_demops);
          if (res == NULL && errno != EINVAL)
                  mdb_warn("Error while demangling");
  
-         mdb_free(dmp->dm_buf, dmp->dm_len);
-         dmp->dm_dem = NULL;
-         dmp->dm_len = 0;
- 
          reslen = (res != NULL) ? strlen(res) : 0;
          reslen += prefixlen;
          reslen += 1;
  
          dmp->dm_buf = mdb_zalloc(reslen, UM_SLEEP);
          if (dmp->dm_buf == NULL) {
                  mdb_warn("Unable to allocate memory for demangling");
                  return (-1);
          }
- 
          dmp->dm_len = reslen;
  
          if (prefixlen > 0)
                  (void) strlcpy(dmp->dm_buf, name, prefixlen);
          if (res != NULL)
                  (void) strlcat(dmp->dm_buf, res, dmp->dm_len);
--- 209,233 ----
  
          res = sysdemangle(name + prefixlen, dmp->dm_lang, &mdb_dem_demops);
          if (res == NULL && errno != EINVAL)
                  mdb_warn("Error while demangling");
  
          reslen = (res != NULL) ? strlen(res) : 0;
          reslen += prefixlen;
          reslen += 1;
  
+         if (reslen > dmp->dm_len) {
+                 mdb_free(dmp->dm_buf, dmp->dm_len);
+ 
                  dmp->dm_buf = mdb_zalloc(reslen, UM_SLEEP);
                  if (dmp->dm_buf == NULL) {
+                         dmp->dm_len = 0;
                          mdb_warn("Unable to allocate memory for demangling");
                          return (-1);
                  }
                  dmp->dm_len = reslen;
+         }
  
          if (prefixlen > 0)
                  (void) strlcpy(dmp->dm_buf, name, prefixlen);
          if (res != NULL)
                  (void) strlcat(dmp->dm_buf, res, dmp->dm_len);