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Bug#32528 Global read lock with a low priority write lock causes a server crash

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FLUSH TABLES WITH READ LOCK fails to properly detect write locked
tables when running under low priority updates.

The problem is that when trying to aspire a global read lock, the
reload_acl_and_cache() function fails to properly check if the thread
has a low priority write lock, which later my cause a server crash or
deadlock.

The solution is to simple check if the thread has any type of the
possible exclusive write locks.


mysql-test/r/flush.result:
  Add test case result for Bug#32528
mysql-test/t/flush.test:
  Add test case for Bug#32528
sql/sql_parse.cc:
  Although it should not matter under LOCK TABLES, use TL_WRITE_ALLOW_WRITE
  to emphasize that it should fail in case of any write lock.
This commit is contained in:
unknown 2007-11-22 10:18:19 -02:00
parent 2aa5037c7a
commit 719e64e4a5
3 changed files with 49 additions and 1 deletions
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17
mysql-test/r/flush.result
View File

@ -55,3 +55,20 @@ flush tables with read lock;
insert into t2 values(1);
unlock tables;
drop table t1, t2;
drop table if exists t1, t2;
set session low_priority_updates=1;
create table t1 (a int);
create table t2 (b int);
lock tables 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
unlock tables;
lock tables t1 read, t2 write;
flush tables with read lock;
ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
unlock tables;
lock tables t1 read;
flush tables with read lock;
unlock tables;
drop table t1, t2;
set session low_priority_updates=default;

31
mysql-test/t/flush.test
View File

@ -133,4 +133,35 @@ disconnect con3;
connection default;
drop table t1, t2;
#
# Bug#32528 Global read lock with a low priority write lock causes a server crash
#
--disable_warnings
drop table if exists t1, t2;
--enable_warnings
set session low_priority_updates=1;
create table t1 (a int);
create table t2 (b int);
lock tables t1 write;
--error ER_LOCK_OR_ACTIVE_TRANSACTION
flush tables with read lock;
unlock tables;
lock tables t1 read, t2 write;
--error ER_LOCK_OR_ACTIVE_TRANSACTION
flush tables with read lock;
unlock tables;
lock tables t1 read;
flush tables with read lock;
unlock tables;
drop table t1, t2;
set session low_priority_updates=default;
# End of 5.0 tests

2
sql/sql_parse.cc
View File

@ -7054,7 +7054,7 @@ bool reload_acl_and_cache(THD *thd, ulong options, TABLE_LIST *tables,
for (; lock_p < end_p; lock_p++)
{
if ((*lock_p)->type == TL_WRITE)
if ((*lock_p)->type >= TL_WRITE_ALLOW_WRITE)
{
my_error(ER_LOCK_OR_ACTIVE_TRANSACTION, MYF(0));
return 1;