From 706247caae4c33f788a621e643262570c6707ec9 Mon Sep 17 00:00:00 2001
From: "evgen@moonbone.local" <>
Date: Wed, 3 Aug 2005 02:01:27 +0400
Subject: [PATCH] Fix bug #11934 Two sequential FLUSH TABLES WITH READ LOCK
 hangs client

Bug was introduced by cset 1.1659.14.1. Before it server was silently
ignoring that lock can't be acquired because it already acquired.

This patch makes make_global_read_lock_block_commit() return without error
if lock already acquired.
---
 mysql-test/r/flush_table.result | 3 +++
 mysql-test/t/flush_table.test   | 7 +++++++
 sql/lock.cc                     | 2 +-
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/mysql-test/r/flush_table.result b/mysql-test/r/flush_table.result
index 2ef4ab5b52b..db54d2e53ef 100644
--- a/mysql-test/r/flush_table.result
+++ b/mysql-test/r/flush_table.result
@@ -101,3 +101,6 @@ table_id
 Record-02
 handler t1 close;
 drop table t1;
+FLUSH TABLES WITH READ LOCK ;
+FLUSH TABLES WITH READ LOCK ;
+UNLOCK TABLES;
diff --git a/mysql-test/t/flush_table.test b/mysql-test/t/flush_table.test
index 0330582bc34..e46b67ad3d0 100644
--- a/mysql-test/t/flush_table.test
+++ b/mysql-test/t/flush_table.test
@@ -73,4 +73,11 @@ handler t1 read next limit 1;
 handler t1 close;
 drop table t1;
 
+#
+# Bug #11934 Two sequential FLUSH TABLES WITH READ LOCK hangs client
+#
+FLUSH TABLES WITH READ LOCK ;
+FLUSH TABLES WITH READ LOCK ;
+UNLOCK TABLES;
+
 # End of 4.1 tests
diff --git a/sql/lock.cc b/sql/lock.cc
index d51d9083058..568ca2b68af 100644
--- a/sql/lock.cc
+++ b/sql/lock.cc
@@ -990,7 +990,7 @@ bool make_global_read_lock_block_commit(THD *thd)
     make_global_read_lock_block_commit(), do nothing.
   */
   if (thd->global_read_lock != GOT_GLOBAL_READ_LOCK)
-    DBUG_RETURN(1);
+    DBUG_RETURN(0);
   pthread_mutex_lock(&LOCK_global_read_lock);
   /* increment this BEFORE waiting on cond (otherwise race cond) */
   global_read_lock_blocks_commit++;