bk commit into 4.1 tree (ingo:1.2361) BUG#9459

[ingo]

Below is the list of changes that have just been committed into a local
4.1 repository of mydev. When mydev does a push these changes will
be propagated to the main repository and, within 24 hours after the
push, to the public repository.
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ChangeSet
  1.2361 05/08/05 15:37:24 ingo@stripped +3 -0
  Bug#9459 - deadlock with flush with lock, and lock table write
  Added a check before taking a global read lock if
  the own thread has a write locked table.

  sql/sql_parse.cc
    1.456 05/08/05 15:37:18 ingo@stripped +17 -0
    Bug#9459 - deadlock with flush with lock, and lock table write
    Added a check before taking a global read lock if
    the own thread has a write locked table.

  mysql-test/t/flush.test
    1.16 05/08/05 15:37:18 ingo@stripped +31 -0
    Bug#9459 - deadlock with flush with lock, and lock table write
    The test case.

  mysql-test/r/flush.result
    1.12 05/08/05 15:37:18 ingo@stripped +21 -0
    Bug#9459 - deadlock with flush with lock, and lock table write
    The test result.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	ingo
# Host:	chilla.local
# Root:	/home/mydev/mysql-4.1-4100

--- 1.455/sql/sql_parse.cc	2005-08-02 02:12:27 +02:00
+++ 1.456/sql/sql_parse.cc	2005-08-05 15:37:18 +02:00
@@ -5028,6 +5028,23 @@
     if ((options & REFRESH_READ_LOCK) && thd)
     {
       /*
+        We must not try to aspire a global read lock if we have a write
+        locked table. This would lead to a deadlock when trying to
+        reopen (and re-lock) the table after the flush.
+      */
+      if (thd->locked_tables)
+      {
+        THR_LOCK_DATA **lock_p= thd->locked_tables->locks;
+        THR_LOCK_DATA **end_p= lock_p + thd->locked_tables->lock_count;
+
+        for (; lock_p < end_p; lock_p++)
+          if ((*lock_p)->type == TL_WRITE)
+          {
+            my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
+            return 1;
+          }
+      }
+      /*
 	Writing to the binlog could cause deadlocks, as we don't log
 	UNLOCK TABLES
       */

--- 1.11/mysql-test/r/flush.result	2003-08-07 20:17:21 +02:00
+++ 1.12/mysql-test/r/flush.result	2005-08-05 15:37:18 +02:00
@@ -27,3 +27,24 @@
 n
 345
 drop table t1;
+create table t1 (c1 int);
+lock table t1 write;
+flush tables with read lock;
+ERROR HY000: Can't execute the given command because you have active locked tables or an
active transaction
+lock table t1 read;
+flush tables with read lock;
+lock table t1 write;
+ERROR HY000: Can't execute the query because you have a conflicting read lock
+lock table t1 read;
+lock table t1 write;
+ERROR HY000: Can't execute the query because you have a conflicting read lock
+unlock tables;
+create table t2 (c1 int);
+create table t3 (c1 int);
+lock table t1 read, t2 read, t3 write;
+flush tables with read lock;
+ERROR HY000: Can't execute the given command because you have active locked tables or an
active transaction
+lock table t1 read, t2 read, t3 read;
+flush tables with read lock;
+unlock tables;
+drop table t1, t2, t3;

--- 1.15/mysql-test/t/flush.test	2005-07-28 02:21:41 +02:00
+++ 1.16/mysql-test/t/flush.test	2005-08-05 15:37:18 +02:00
@@ -70,4 +70,35 @@
 select * from t1;
 drop table t1;
 
+#
+# Bug#9459 - deadlock with flush with lock, and lock table write
+#
+create table t1 (c1 int);
+lock table t1 write;
+# Cannot get the global read lock with write locked tables.
+--error 1192
+flush tables with read lock;
+lock table t1 read;
+# Can get the global read lock with read locked tables.
+flush tables with read lock;
+--error 1223
+lock table t1 write;
+lock table t1 read;
+--error 1223
+lock table t1 write;
+# Release all table locks and the global read lock.
+unlock tables;
+create table t2 (c1 int);
+create table t3 (c1 int);
+lock table t1 read, t2 read, t3 write;
+# Cannot get the global read lock with write locked tables.
+--error 1192
+flush tables with read lock;
+lock table t1 read, t2 read, t3 read;
+# Can get the global read lock with read locked tables.
+flush tables with read lock;
+# Release all table locks and the global read lock.
+unlock tables;
+drop table t1, t2, t3;
+
 # End of 4.1 tests