Backport of:

------------------------------------------------------------
revno: 2476.784.3
committer: davi@moksha.local
timestamp: Tue 2007-10-02 21:27:31 -0300
message:
Bug#25858 Some DROP TABLE under LOCK TABLES can cause deadlocks
        
When a client (connection) holds a lock on a table and attempts to
drop (obtain a exclusive lock) on a second table that is already
held by a second client and the second client then attempts to
drop the table that is held by the first client, leads to a
circular wait deadlock. This scenario is very similar to trying to
drop (or rename) a table while holding read locks and are
correctly forbidden.
        
The solution is to allow a drop table operation to continue only
if the table being dropped is write (exclusively) locked, or if
the table is temporary, or if the client is not holding any
locks. Using this scheme prevents the creation of a circular
chain in which each client is waiting for one table that the
next client in the chain is holding.
            
This is incompatible change, as can be seen by number of tests
cases that needed to be fixed, but is consistent with respect to
behavior of the different scenarios in which the circular wait
might happen.

mysql-test/r/drop.result:
  Test case result for Bug#25858
mysql-test/r/group_by.result:
  Fix test case result wrt drop table under lock tables -- unlock tables
  before dropping table.
mysql-test/r/insert_notembedded.result:
  Fix test case result wrt drop table under lock tables -- unlock tables
  before dropping table
mysql-test/r/lock.result:
  Fix test case result wrt drop table under lock tables -- unlock tables
  before dropping table.
mysql-test/r/lock_multi.result:
  Fix test case result wrt drop table under lock tables -- unlock tables
  before dropping table.
mysql-test/r/myisam.result:
  Fix test case result wrt drop table under lock tables -- unlock tables
  before dropping table.
mysql-test/r/view.result:
  Fix test case result wrt drop table under lock tables -- unlock tables
  before dropping table.
mysql-test/t/drop.test:
  Add test case for Bug#25858
mysql-test/t/group_by.test:
  Fix test case: unlock tables in preparation for a drop table. In some
  circumstances, dropping tables while holding locks leads to a deadlock.
mysql-test/t/insert_notembedded.test:
  Fix test case: unlock tables in preparation for a drop table. In some
  circumstances, dropping tables while holding locks leads to a deadlock.
mysql-test/t/lock.test:
  Fix test case: unlock tables in preparation for a drop table. In some
  circumstances, dropping tables while holding locks leads to a deadlock.
mysql-test/t/lock_multi.test:
  Fix test case: unlock tables in preparation for a drop table. In some
  circumstances, dropping tables while holding locks leads to a deadlock.
mysql-test/t/myisam.test:
  Fix test case: unlock tables in preparation for a drop table. In some
  circumstances, dropping tables while holding locks leads to a deadlock.
mysql-test/t/query_cache_notembedded.test:
  Fix test case: unlock tables in preparation for a drop table. In some
  circumstances, dropping tables while holding locks leads to a deadlock.
mysql-test/t/view.test:
  Fix test case: unlock tables in preparation for a drop table. In some
  circumstances, dropping tables while holding locks leads to a deadlock.
sql/lock.cc:
  When trying to obtain a name lock under lock tables, ensure that the table is properly exclusively locked and fail otherwise.

17 files changed, 104 insertions, 2 deletions

diff --git a/mysql-test/r/drop.result b/mysql-test/r/drop.result
index 42739b10d50..54bd05e526f 100644
--- a/mysql-test/r/drop.result
+++ b/mysql-test/r/drop.result
@@ -86,6 +86,26 @@ select 1;
 1
 1
 unlock tables;
+drop table if exists t1,t2;
+create table t1 (a int);
+create table t2 (a int);
+lock table t1 read;
+drop table t2;
+ERROR HY000: Table 't2' was not locked with LOCK TABLES
+drop table t1;
+ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
+unlock tables;
+drop table t1,t2;
+create table t1 (i int);
+create table t2 (i int);
+lock tables t1 read;
+lock tables t2 read;
+drop table t1;
+ERROR HY000: Table 't1' was not locked with LOCK TABLES
+drop table t1,t2;
+ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
+unlock tables;
+drop table t1,t2;
 End of 5.0 tests
 create database mysql_test;
 create table mysql_test.t1(f1 int);
diff --git a/mysql-test/r/group_by.result b/mysql-test/r/group_by.result
index 742d4b90807..e6063047ba4 100644
--- a/mysql-test/r/group_by.result
+++ b/mysql-test/r/group_by.result
@@ -107,8 +107,9 @@ SELECT cid, CONCAT(firstname, ' ', surname), COUNT(call_id) FROM t1 LEFT JOIN t2
 cid	CONCAT(firstname, ' ', surname)	COUNT(call_id)
 SELECT HIGH_PRIORITY cid, CONCAT(firstname, ' ', surname), COUNT(call_id) FROM t1 LEFT JOIN t2 ON cid=contact_id WHERE firstname like '%foo%' GROUP BY cid ORDER BY surname, firstname;
 cid	CONCAT(firstname, ' ', surname)	COUNT(call_id)
-drop table t1,t2;
+drop table t2;
 unlock tables;
+drop table t1;
 CREATE TABLE t1 (
 bug_id mediumint(9) NOT NULL auto_increment,
 groupset bigint(20) DEFAULT '0' NOT NULL,
diff --git a/mysql-test/r/insert_notembedded.result b/mysql-test/r/insert_notembedded.result
index ac69cb65972..2315d695abe 100644
--- a/mysql-test/r/insert_notembedded.result
+++ b/mysql-test/r/insert_notembedded.result
@@ -122,5 +122,6 @@ a	b
 connection: default
 select * from t1;
 a	b
+unlock tables;
 drop table t1;
 set low_priority_updates=default;
diff --git a/mysql-test/r/lock.result b/mysql-test/r/lock.result
index 7ec07fb5273..1f8f6aa04ae 100644
--- a/mysql-test/r/lock.result
+++ b/mysql-test/r/lock.result
@@ -48,6 +48,9 @@ unlock tables;
 lock tables t1 write, t1 as t1_alias read;
 insert into t1 select index1,nr from t1 as t1_alias;
 drop table t1,t2;
+ERROR HY000: Table 't2' was not locked with LOCK TABLES
+unlock tables;
+drop table t1,t2;
 create table t1 (c1 int);
 create table t2 (c1 int);
 create table t3 (c1 int);
@@ -69,6 +72,9 @@ ERROR HY000: Table 't2' was locked with a READ lock and can't be updated
 delete t2 from t1,t2 where t1.a=t2.a;
 ERROR HY000: Table 't2' was locked with a READ lock and can't be updated
 drop table t1,t2;
+ERROR HY000: Table 't2' was locked with a READ lock and can't be updated
+unlock tables;
+drop table t2,t1;
 End of 4.1 tests.
 drop table if exists t1;
 create table t1 (a int);
diff --git a/mysql-test/r/lock_multi.result b/mysql-test/r/lock_multi.result
index d8768e802ea..49e51631b91 100644
--- a/mysql-test/r/lock_multi.result
+++ b/mysql-test/r/lock_multi.result
@@ -27,6 +27,7 @@ update t1,t2 set c=a where b=d;
 select c from t2;
 c
 2
+unlock tables;
 drop table t1;
 drop table t2;
 create table t1 (a int);
diff --git a/mysql-test/r/myisam.result b/mysql-test/r/myisam.result
index 95fdc4fb93d..16e8a8e5ad1 100644
--- a/mysql-test/r/myisam.result
+++ b/mysql-test/r/myisam.result
@@ -529,6 +529,7 @@ select straight_join * from t1,t2 force index (primary) where t1.a=t2.a;
 a	a	b
 1	1	1
 2	2	1
+unlock tables;
 drop table t1,t2;
 CREATE TABLE t1 (c1 varchar(250) NOT NULL);
 CREATE TABLE t2 (c1 varchar(250) NOT NULL, PRIMARY KEY (c1));
@@ -542,6 +543,7 @@ INSERT INTO t2 VALUES ('test000001'), ('test000005');
 SELECT t1.c1 AS t1c1, t2.c1 AS t2c1 FROM t1, t2
 WHERE t1.c1 = t2.c1 HAVING t1c1 != t2c1;
 t1c1	t2c1
+UNLOCK TABLES;
 DROP TABLE t1,t2;
 CREATE TABLE t1 (`a` int(11) NOT NULL default '0', `b` int(11) NOT NULL default '0', UNIQUE KEY `a` USING RTREE (`a`,`b`)) ENGINE=MyISAM;
 Got one of the listed errors
diff --git a/mysql-test/r/query_cache_notembedded.result b/mysql-test/r/query_cache_notembedded.result
index d9bf7a6d814..25894634bf3 100644
--- a/mysql-test/r/query_cache_notembedded.result
+++ b/mysql-test/r/query_cache_notembedded.result
@@ -93,6 +93,7 @@ a
 3
 SELECT * FROM t1;
 a
+UNLOCK TABLES;
 drop table t1;
 flush query cache;
 reset query cache;
diff --git a/mysql-test/r/view.result b/mysql-test/r/view.result
index 69bcf349f51..2df2b0bafa6 100644
--- a/mysql-test/r/view.result
+++ b/mysql-test/r/view.result
@@ -1104,6 +1104,9 @@ select * from t2;
 ERROR HY000: Table 't2' was not locked with LOCK TABLES
 drop view v1;
 drop table t1, t2;
+ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
+unlock tables;
+drop table t1, t2;
 create table t1 (a int);
 create view v1 as select * from t1 where a < 2 with check option;
 insert into v1 values(1);
diff --git a/mysql-test/t/drop.test b/mysql-test/t/drop.test
index 6be4ea25007..4aeb7165bcb 100644
--- a/mysql-test/t/drop.test
+++ b/mysql-test/t/drop.test
@@ -124,6 +124,39 @@ disconnect addconroot1;
 --source include/wait_until_disconnected.inc
 connection default;
 
+#
+# Bug#25858 Some DROP TABLE under LOCK TABLES can cause deadlocks
+#
+
+--disable_warnings
+drop table if exists t1,t2;
+--enable_warnings
+create table t1 (a int);
+create table t2 (a int);
+lock table t1 read;
+--error ER_TABLE_NOT_LOCKED
+drop table t2;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+drop table t1;
+unlock tables;
+drop table t1,t2;
+connect (addconroot, localhost, root,,);
+connection default;
+create table t1 (i int);
+create table t2 (i int);
+lock tables t1 read;
+connection addconroot;
+lock tables t2 read;
+--error ER_TABLE_NOT_LOCKED
+drop table t1;
+connection default;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+drop table t1,t2;
+disconnect addconroot;
+connection default;
+unlock tables;
+drop table t1,t2;
+
 --echo End of 5.0 tests
 
 #
diff --git a/mysql-test/t/group_by.test b/mysql-test/t/group_by.test
index 5b96213034a..7ed8dfe5784 100644
--- a/mysql-test/t/group_by.test
+++ b/mysql-test/t/group_by.test
@@ -120,8 +120,9 @@ SELECT cid, CONCAT(firstname, ' ', surname), COUNT(call_id) FROM t1 LEFT JOIN t2
 SELECT cid, CONCAT(firstname, ' ', surname), COUNT(call_id) FROM t1 LEFT JOIN t2 ON cid=contact_id WHERE firstname like '%foo%' GROUP BY cid ORDER BY NULL;
 SELECT HIGH_PRIORITY cid, CONCAT(firstname, ' ', surname), COUNT(call_id) FROM t1 LEFT JOIN t2 ON cid=contact_id WHERE firstname like '%foo%' GROUP BY cid ORDER BY surname, firstname;
 
-drop table t1,t2;
+drop table t2;
 unlock tables;
+drop table t1;
 
 #
 # Test of group by bug in bugzilla
diff --git a/mysql-test/t/insert_notembedded.test b/mysql-test/t/insert_notembedded.test
index 24040f9c310..2950acff3cc 100644
--- a/mysql-test/t/insert_notembedded.test
+++ b/mysql-test/t/insert_notembedded.test
@@ -185,5 +185,6 @@ select * from t1;
 connection default;
 disconnect update;
 disconnect select;
+unlock tables;
 drop table t1;
 set low_priority_updates=default;
diff --git a/mysql-test/t/lock.test b/mysql-test/t/lock.test
index 30f4d4d6c61..04994e3e48f 100644
--- a/mysql-test/t/lock.test
+++ b/mysql-test/t/lock.test
@@ -58,6 +58,9 @@ insert into t1 select index1,nr from t1;
 unlock tables;
 lock tables t1 write, t1 as t1_alias read;
 insert into t1 select index1,nr from t1 as t1_alias;
+--error ER_TABLE_NOT_LOCKED
+drop table t1,t2;
+unlock tables;
 drop table t1,t2;
 
 #
@@ -90,7 +93,10 @@ delete t1 from t1,t2 where t1.a=t2.a;
 delete from t2 using t1,t2 where t1.a=t2.a;
 --error 1099
 delete t2 from t1,t2 where t1.a=t2.a;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
 drop table t1,t2;
+unlock tables;
+drop table t2,t1;
 
 --echo End of 4.1 tests.
 
diff --git a/mysql-test/t/lock_multi.test b/mysql-test/t/lock_multi.test
index dbaa96b0374..cd4d70bd99e 100644
--- a/mysql-test/t/lock_multi.test
+++ b/mysql-test/t/lock_multi.test
@@ -76,6 +76,7 @@ update t1,t2 set c=a where b=d;
 connection reader;
 select c from t2;
 connection locker;
+unlock tables;
 drop table t1;
 drop table t2;
 
diff --git a/mysql-test/t/myisam.test b/mysql-test/t/myisam.test
index 56fe103adc9..3ee61dcbc1f 100644
--- a/mysql-test/t/myisam.test
+++ b/mysql-test/t/myisam.test
@@ -503,6 +503,7 @@ insert into t2 values(2,0);
 disconnect root;
 connection default;
 select straight_join * from t1,t2 force index (primary) where t1.a=t2.a;
+unlock tables;
 drop table t1,t2;
 #
 # Full key.
@@ -520,6 +521,7 @@ disconnect con1;
 connection default;
 SELECT t1.c1 AS t1c1, t2.c1 AS t2c1 FROM t1, t2
   WHERE t1.c1 = t2.c1 HAVING t1c1 != t2c1;
+UNLOCK TABLES;
 DROP TABLE t1,t2;
 
 # End of 4.0 tests
diff --git a/mysql-test/t/query_cache_notembedded.test b/mysql-test/t/query_cache_notembedded.test
index 095d47f5bdf..77033ced564 100644
--- a/mysql-test/t/query_cache_notembedded.test
+++ b/mysql-test/t/query_cache_notembedded.test
@@ -99,6 +99,7 @@ connection root2;
 SELECT * FROM t1;
 connection root;
 SELECT * FROM t1;
+UNLOCK TABLES;
 drop table t1;
 connection default;
 disconnect root;
diff --git a/mysql-test/t/view.test b/mysql-test/t/view.test
index b2490847dbc..abf8dac2870 100644
--- a/mysql-test/t/view.test
+++ b/mysql-test/t/view.test
@@ -1017,6 +1017,9 @@ select * from v1;
 -- error ER_TABLE_NOT_LOCKED
 select * from t2;
 drop view v1;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+drop table t1, t2;
+unlock tables;
 drop table t1, t2;
 
 #
diff --git a/sql/lock.cc b/sql/lock.cc
index 112d3dc4a2b..6cdd654fb92 100644
--- a/sql/lock.cc
+++ b/sql/lock.cc
@@ -1028,6 +1028,7 @@ int lock_table_name(THD *thd, TABLE_LIST *table_list, bool check_in_use)
   char  key[MAX_DBKEY_LENGTH];
   char *db= table_list->db;
   uint  key_length;
+  bool  found_locked_table= FALSE;
   HASH_SEARCH_STATE state;
   DBUG_ENTER("lock_table_name");
   DBUG_PRINT("enter",("db: %s  name: %s", db, table_list->table_name));
@@ -1043,6 +1044,13 @@ int lock_table_name(THD *thd, TABLE_LIST *table_list, bool check_in_use)
          table = (TABLE*) my_hash_next(&open_cache,(uchar*) key,
                                        key_length, &state))
     {
+      if (table->reginfo.lock_type < TL_WRITE)
+      {
+        if (table->in_use == thd)
+          found_locked_table= TRUE;
+        continue;
+      }
+
       if (table->in_use == thd)
       {
         DBUG_PRINT("info", ("Table is in use"));
@@ -1053,6 +1061,17 @@ int lock_table_name(THD *thd, TABLE_LIST *table_list, bool check_in_use)
     }
   }
 
+  if (thd->locked_tables && thd->locked_tables->table_count &&
+      ! find_temporary_table(thd, table_list->db, table_list->table_name))
+  {
+    if (found_locked_table)
+      my_error(ER_TABLE_NOT_LOCKED_FOR_WRITE, MYF(0), table_list->alias);
+    else
+      my_error(ER_TABLE_NOT_LOCKED, MYF(0), table_list->alias);
+
+    DBUG_RETURN(-1);
+  }
+
   if (!(table= table_cache_insert_placeholder(thd, key, key_length)))
     DBUG_RETURN(-1);