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MDEV-5616 - Deadlock between CREATE/DROP FUNCTION and SELECT from view

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Deadlock happened due to mixed lock order.
CREATE/DROP function: wrlock(THR_LOCK_udf) -> lock(LOCK_open)
SELECT from view: lock(LOCK_open) -> rdlock(THR_LOCK_udf)

Fixed CREATE/DROP function so that LOCK_open does not intersect with
wrlock(THR_LOCK_udf).

10.0 is not affected: it doesn't hold LOCK_open while opening view.
This commit is contained in:
Sergey Vojtovich 2014-02-13 16:41:08 +04:00
parent 528df1df45
commit e2a99f1863
3 changed files with 73 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
mysql-test/r/udf_debug_sync.result Normal file
View File

@ -0,0 +1,20 @@
CREATE FUNCTION myfunc_int RETURNS INTEGER SONAME "UDF_EXAMPLE_LIB";
CREATE VIEW v1 AS SELECT myfunc_int(1);
SET debug_sync='mysql_create_function_after_lock SIGNAL locked WAIT_FOR go';
CREATE FUNCTION myfunc_double RETURNS REAL SONAME "UDF_EXAMPLE_LIB";
SET debug_sync='now WAIT_FOR locked';
SET debug_sync='find_udf_before_lock SIGNAL go';
SELECT * FROM v1;
myfunc_int(1)
1
FLUSH TABLES;
SET debug_sync='mysql_drop_function_after_lock SIGNAL locked WAIT_FOR go';
DROP FUNCTION myfunc_double;
SET debug_sync='now WAIT_FOR locked';
SET debug_sync='find_udf_before_lock SIGNAL go';
SELECT * FROM v1;
myfunc_int(1)
1
SET debug_sync='RESET';
DROP VIEW v1;
DROP FUNCTION myfunc_int;

40
mysql-test/t/udf_debug_sync.test Normal file
View File

@ -0,0 +1,40 @@
--source include/have_debug_sync.inc
--source include/have_udf.inc
#
# MDEV-5616 - Deadlock between CREATE/DROP FUNCTION and SELECT from view
#
--replace_result $UDF_EXAMPLE_SO UDF_EXAMPLE_LIB
eval CREATE FUNCTION myfunc_int RETURNS INTEGER SONAME "$UDF_EXAMPLE_SO";
CREATE VIEW v1 AS SELECT myfunc_int(1);
connect(con1, localhost, root,,);
connection con1;
SET debug_sync='mysql_create_function_after_lock SIGNAL locked WAIT_FOR go';
--replace_result $UDF_EXAMPLE_SO UDF_EXAMPLE_LIB
send_eval CREATE FUNCTION myfunc_double RETURNS REAL SONAME "$UDF_EXAMPLE_SO";
connection default;
SET debug_sync='now WAIT_FOR locked';
SET debug_sync='find_udf_before_lock SIGNAL go';
SELECT * FROM v1;
FLUSH TABLES;
connection con1;
reap;
SET debug_sync='mysql_drop_function_after_lock SIGNAL locked WAIT_FOR go';
send DROP FUNCTION myfunc_double;
connection default;
SET debug_sync='now WAIT_FOR locked';
SET debug_sync='find_udf_before_lock SIGNAL go';
SELECT * FROM v1;
connection con1;
reap;
disconnect con1;
connection default;
SET debug_sync='RESET';
DROP VIEW v1;
DROP FUNCTION myfunc_int;

18
sql/sql_udf.cc
View File

@ -352,6 +352,7 @@ udf_func *find_udf(const char *name,uint length,bool mark_used)
if (!initialized)
DBUG_RETURN(NULL);
DEBUG_SYNC(current_thd, "find_udf_before_lock");
/* TODO: This should be changed to reader locks someday! */
if (mark_used)
mysql_rwlock_wrlock(&THR_LOCK_udf); /* Called during fix_fields */
@ -466,7 +467,12 @@ int mysql_create_function(THD *thd,udf_func *udf)
if ((save_binlog_row_based= thd->is_current_stmt_binlog_format_row()))
thd->clear_current_stmt_binlog_format_row();
tables.init_one_table(STRING_WITH_LEN("mysql"), STRING_WITH_LEN("func"),
"func", TL_WRITE);
table= open_ltable(thd, &tables, TL_WRITE, MYSQL_LOCK_IGNORE_TIMEOUT);
mysql_rwlock_wrlock(&THR_LOCK_udf);
DEBUG_SYNC(current_thd, "mysql_create_function_after_lock");
if ((my_hash_search(&udf_hash,(uchar*) udf->name.str, udf->name.length)))
{
my_error(ER_UDF_EXISTS, MYF(0), udf->name.str);
@ -510,9 +516,8 @@ int mysql_create_function(THD *thd,udf_func *udf)
/* create entry in mysql.func table */
tables.init_one_table("mysql", 5, "func", 4, "func", TL_WRITE);
/* Allow creation of functions even if we can't open func table */
if (!(table = open_ltable(thd, &tables, TL_WRITE, MYSQL_LOCK_IGNORE_TIMEOUT)))
if (!table)
goto err;
table->use_all_columns();
restore_record(table, s->default_values); // Default values for fields
@ -584,7 +589,12 @@ int mysql_drop_function(THD *thd,const LEX_STRING *udf_name)
if ((save_binlog_row_based= thd->is_current_stmt_binlog_format_row()))
thd->clear_current_stmt_binlog_format_row();
tables.init_one_table(STRING_WITH_LEN("mysql"), STRING_WITH_LEN("func"),
"func", TL_WRITE);
table= open_ltable(thd, &tables, TL_WRITE, MYSQL_LOCK_IGNORE_TIMEOUT);
mysql_rwlock_wrlock(&THR_LOCK_udf);
DEBUG_SYNC(current_thd, "mysql_drop_function_after_lock");
if (!(udf=(udf_func*) my_hash_search(&udf_hash,(uchar*) udf_name->str,
(uint) udf_name->length)))
{
@ -601,9 +611,7 @@ int mysql_drop_function(THD *thd,const LEX_STRING *udf_name)
if (udf->dlhandle && !find_udf_dl(udf->dl))
dlclose(udf->dlhandle);
tables.init_one_table("mysql", 5, "func", 4, "func", TL_WRITE);
if (!(table = open_ltable(thd, &tables, TL_WRITE, MYSQL_LOCK_IGNORE_TIMEOUT)))
if (!table)
goto err;
table->use_all_columns();
table->field[0]->store(exact_name_str, exact_name_len, &my_charset_bin);