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Bug#52856 concurrent show columns or show full columns causes a crash!!!1

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We should avoid any SHARE fields assignments as
this is shared structure and assignments may
affect other therads. To avoid this
copy of SHARE struct is created and
stored into TABLE struct which is
used in get_schema_coulumns_record later.



mysql-test/r/mdl_sync.result:
  test case
mysql-test/t/mdl_sync.test:
  test case
sql/sql_show.cc:
  We should avoid any SHARE fields assignments as
  this is shared structure and assignments may
  affect other therads. To avoid this
  copy of SHARE struct is created and
  stored into TABLE struct which is
  used in get_schema_coulumns_record later.
This commit is contained in:
Sergey Glukhov 2010-05-27 19:54:43 +04:00
parent bac571e136
commit 8fa381fda3
3 changed files with 45 additions and 34 deletions
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14
mysql-test/r/mdl_sync.result
View file

@ -2381,3 +2381,17 @@ commit;
# Reap ALTER TABLE.
set debug_sync= 'RESET';
drop table t1;
#
# Bug#52856 concurrent show columns or show full columns causes a crash!!!
#
CREATE TABLE t1(a CHAR(255));
SET DEBUG_SYNC= "get_schema_column SIGNAL waiting WAIT_FOR completed";
SHOW FULL COLUMNS FROM t1;
SET DEBUG_SYNC= "now WAIT_FOR waiting";
SHOW FULL COLUMNS FROM t1;
Field Type Collation Null Key Default Extra Privileges Comment
a char(255) latin1_swedish_ci YES NULL select,insert,update,references
SET DEBUG_SYNC= "now SIGNAL completed";
Field Type Collation Null Key Default Extra Privileges Comment
a char(255) latin1_swedish_ci YES NULL select,insert,update,references
DROP TABLE t1;

20
mysql-test/t/mdl_sync.test
View file

@ -3468,6 +3468,26 @@ connection default;
set debug_sync= 'RESET';
drop table t1;
--echo #
--echo # Bug#52856 concurrent show columns or show full columns causes a crash!!!
--echo #
CREATE TABLE t1(a CHAR(255));
connect(con1, localhost, root);
SET DEBUG_SYNC= "get_schema_column SIGNAL waiting WAIT_FOR completed";
--send SHOW FULL COLUMNS FROM t1
connection default;
SET DEBUG_SYNC= "now WAIT_FOR waiting";
SHOW FULL COLUMNS FROM t1;
SET DEBUG_SYNC= "now SIGNAL completed";
connection con1;
--reap
connection default;
DROP TABLE t1;
disconnect con1;
# Check that all connections opened by test cases in this file are really
# gone so execution of other tests won't be affected by their presence.

45
sql/sql_show.cc
View file

@ -18,6 +18,7 @@
#include "my_global.h" /* NO_EMBEDDED_ACCESS_CHECKS */
#include "sql_priv.h"
#include "debug_sync.h"
#include "unireg.h"
#include "sql_acl.h" // fill_schema_*_privileges
#include "sql_select.h" // For select_describe
@ -3292,12 +3293,17 @@ static int fill_schema_table_from_frm(THD *thd, TABLE_LIST *tables,
goto end_share;
}
if (!open_table_from_share(thd, share, table_name->str, 0,
(EXTRA_RECORD | OPEN_FRM_FILE_ONLY),
thd->open_options, &tbl, FALSE))
{
tbl.s= share;
table_list.table= &tbl;
table_list.view= (LEX*) share->is_view;
res= schema_table->process_table(thd, &table_list, table,
res, db_name, table_name);
free_root(&tbl.mem_root, MYF(0));
my_free((char*) tbl.alias, MYF(MY_ALLOW_ZERO_PTR));
}
end_share:
@ -4024,7 +4030,6 @@ static int get_schema_column_record(THD *thd, TABLE_LIST *tables,
const char *wild= lex->wild ? lex->wild->ptr() : NullS;
CHARSET_INFO *cs= system_charset_info;
TABLE *show_table;
TABLE_SHARE *show_table_share;
Field **ptr, *field, *timestamp_field;
int count;
DBUG_ENTER("get_schema_column_record");
@ -4047,37 +4052,11 @@ static int get_schema_column_record(THD *thd, TABLE_LIST *tables,
}
show_table= tables->table;
show_table_share= show_table->s;
count= 0;
if (tables->view || tables->schema_table)
{
ptr= show_table->field;
timestamp_field= show_table->timestamp_field;
show_table->use_all_columns(); // Required for default
}
else
{
ptr= show_table_share->field;
timestamp_field= show_table_share->timestamp_field;
/*
read_set may be inited in case of
temporary table
*/
if (!show_table->read_set)
{
/* to satisfy 'field->val_str' ASSERTs */
uchar *bitmaps;
uint bitmap_size= show_table_share->column_bitmap_size;
if (!(bitmaps= (uchar*) alloc_root(thd->mem_root, bitmap_size)))
DBUG_RETURN(0);
bitmap_init(&show_table->def_read_set,
(my_bitmap_map*) bitmaps, show_table_share->fields, FALSE);
bitmap_set_all(&show_table->def_read_set);
show_table->read_set= &show_table->def_read_set;
}
bitmap_set_all(show_table->read_set);
}
ptr= show_table->field;
timestamp_field= show_table->timestamp_field;
show_table->use_all_columns(); // Required for default
restore_record(show_table, s->default_values);
for (; (field= *ptr) ; ptr++)
{
@ -4086,9 +4065,7 @@ static int get_schema_column_record(THD *thd, TABLE_LIST *tables,
String type(tmp,sizeof(tmp), system_charset_info);
char *end;
/* to satisfy 'field->val_str' ASSERTs */
field->table= show_table;
show_table->in_use= thd;
DEBUG_SYNC(thd, "get_schema_column");
if (wild && wild[0] &&
wild_case_compare(system_charset_info, field->field_name,wild))