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MDEV-18154 Deadlock and assertion upon no-op ALTER under LOCK TABLES

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1. Fix DBUG_ASSERT(!table->pos_in_locked_tables) in tc_release_table();
2. Fix access of prematurely freed MDL_ticket: don't close ticket if table was not closed;
3. Fix deadlock after erroneous ALTER.

mysql_alter_table() leaves dirty table->m_needs_reopen in case of
error exit which then incorrectly treated by mysql_lock_tables().
This commit is contained in:
Aleksey Midenkov
2019-02-05 00:57:31 +03:00
parent 0b74c8832d
commit 22914ec793
4 changed files with 42 additions and 1 deletions
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6
sql/sql_table.cc
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@ -7837,6 +7837,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
Create_field *def;
Field **f_ptr,*field;
MY_BITMAP *dropped_fields= NULL; // if it's NULL - no dropped fields
bool save_reopen= table->m_needs_reopen;
DBUG_ENTER("mysql_prepare_alter_table");
/*
@ -8516,7 +8517,9 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
alter_info->create_list.swap(new_create_list);
alter_info->key_list.swap(new_key_list);
alter_info->check_constraint_list.swap(new_constraint_list);
DBUG_RETURN(rc);
err:
table->m_needs_reopen= save_reopen;
DBUG_RETURN(rc);
}
@ -10195,7 +10198,8 @@ err_with_mdl:
tables and release the exclusive metadata lock.
*/
thd->locked_tables_list.unlink_all_closed_tables(thd, NULL, 0);
thd->mdl_context.release_all_locks_for_name(mdl_ticket);
if (!table_list->table)
thd->mdl_context.release_all_locks_for_name(mdl_ticket);
DBUG_RETURN(true);
}