Bug#31479 Bad lock interaction if CREATE TABLE LIKE is killed

Kill of a CREATE TABLE source_table LIKE statement waiting for a
name-lock on the source table causes a bad lock interaction.

The mysql_create_like_table() has a bug that if the connection is
killed while waiting for the name-lock on the source table, it will
jump to the wrong error path and try to unlock the source table and
LOCK_open, but both weren't locked.

The solution is to simple return when the name lock request is killed,
it's safe to do so because no lock was acquired and no cleanup is needed.

Original bug report also contains description of other problems
related to this scenario but they either already fixed in 5.1 or
will be addressed separately (see bug report for details).
parent 9817d93e
...@@ -88,3 +88,14 @@ alter table t1 auto_increment=0; alter table t1 auto_increment=0; alter table t1 ...@@ -88,3 +88,14 @@ alter table t1 auto_increment=0; alter table t1 auto_increment=0; alter table t1
alter table t1 auto_increment=0; alter table t1 auto_increment=0; alter table t1 auto_increment=0; alter table t1 auto_increment=0; alter table t1 auto_increment=0; // alter table t1 auto_increment=0; alter table t1 auto_increment=0; alter table t1 auto_increment=0; alter table t1 auto_increment=0; alter table t1 auto_increment=0; //
unlock tables; unlock tables;
drop table t1; drop table t1;
drop table if exists t1;
create table t1 (a int);
connection: locker
lock tables t1 read;
connection: writer
create table t2 like t1;;
connection: default
kill query
ERROR 70100: Query execution was interrupted
unlock tables;
drop table t1;
...@@ -249,4 +249,36 @@ reap; ...@@ -249,4 +249,36 @@ reap;
connection locker; connection locker;
drop table t1; drop table t1;
#
# Bug#31479 Bad lock interaction if CREATE TABLE LIKE is killed
#
--disable_warnings
drop table if exists t1;
--enable_warnings
create table t1 (a int);
--echo connection: locker
connection locker;
lock tables t1 read;
--echo connection: writer
connection writer;
let $ID= `select connection_id()`;
--send create table t2 like t1;
--echo connection: default
connection default;
let $show_type= open tables where in_use=2 and name_locked=1;
let $show_pattern= '%t1%2%1';
--source include/wait_show_pattern.inc
--echo kill query
disable_query_log;
eval kill query $ID;
enable_query_log;
connection writer;
--error ER_QUERY_INTERRUPTED
--reap
connection locker;
unlock tables;
connection default;
drop table t1;
# End of 5.0 tests # End of 5.0 tests
...@@ -2761,7 +2761,7 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table, TABLE_LIST *src_table, ...@@ -2761,7 +2761,7 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table, TABLE_LIST *src_table,
operations on the target table. operations on the target table.
*/ */
if (lock_and_wait_for_table_name(thd, src_table)) if (lock_and_wait_for_table_name(thd, src_table))
goto err; DBUG_RETURN(res);
pthread_mutex_lock(&LOCK_open); pthread_mutex_lock(&LOCK_open);
......
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