Commit 351c4741 authored by davi@endora.local's avatar davi@endora.local
Browse files

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

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.
parent 9799d6c4

mysql-test/r/flush.result

+17 −0
Original line number Diff line number Diff line
@@ -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;

mysql-test/t/flush.test

+31 −0
Original line number Diff line number Diff line
@@ -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

sql/sql_parse.cc

+1 −1
Original line number Diff line number Diff line
@@ -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;