5.5-merge

1 files changed, 24 insertions, 10 deletions

diff --git a/sql/debug_sync.cc b/sql/debug_sync.cc
index 74e5b2c70f3..7f69ae54037 100644
--- a/sql/debug_sync.cc
+++ b/sql/debug_sync.cc
@@ -1691,7 +1691,7 @@ static void debug_sync_execute(THD *thd, st_debug_sync_action *action)
 
   if (action->execute)
   {
-    const char  *old_proc_info;
+    const char *UNINIT_VAR(old_proc_info);
 
     action->execute--;
 
@@ -1745,11 +1745,20 @@ static void debug_sync_execute(THD *thd, st_debug_sync_action *action)
         We don't use enter_cond()/exit_cond(). They do not save old
         mutex and cond. This would prohibit the use of DEBUG_SYNC
         between other places of enter_cond() and exit_cond().
+
+        We need to check for existence of thd->mysys_var to also make
+        it possible to use DEBUG_SYNC framework in scheduler when this
+        variable has been set to NULL.
       */
-      old_mutex= thd->mysys_var->current_mutex;
-      old_cond= thd->mysys_var->current_cond;
-      thd->mysys_var->current_mutex= &debug_sync_global.ds_mutex;
-      thd->mysys_var->current_cond= &debug_sync_global.ds_cond;
+      if (thd->mysys_var)
+      {
+        old_mutex= thd->mysys_var->current_mutex;
+        old_cond= thd->mysys_var->current_cond;
+        thd->mysys_var->current_mutex= &debug_sync_global.ds_mutex;
+        thd->mysys_var->current_cond= &debug_sync_global.ds_cond;
+      }
+      else
+        old_mutex= NULL;
 
       set_timespec(abstime, action->timeout);
       DBUG_EXECUTE("debug_sync_exec", {
@@ -1804,11 +1813,16 @@ static void debug_sync_execute(THD *thd, st_debug_sync_action *action)
         is locked. (See comment in THD::exit_cond().)
       */
       mysql_mutex_unlock(&debug_sync_global.ds_mutex);
-      mysql_mutex_lock(&thd->mysys_var->mutex);
-      thd->mysys_var->current_mutex= old_mutex;
-      thd->mysys_var->current_cond= old_cond;
-      thd_proc_info(thd, old_proc_info);
-      mysql_mutex_unlock(&thd->mysys_var->mutex);
+      if (old_mutex)
+      {
+        mysql_mutex_lock(&thd->mysys_var->mutex);
+        thd->mysys_var->current_mutex= old_mutex;
+        thd->mysys_var->current_cond= old_cond;
+        thd_proc_info(thd, old_proc_info);
+        mysql_mutex_unlock(&thd->mysys_var->mutex);
+      }
+      else
+        thd_proc_info(thd, old_proc_info);
     }
     else
     {