Bug #21983865 UNEXPECTED DEADLOCK WITH INNODB_AUTOINC_LOCK_MODE=0

Problem:
=======
This bug involves multiple thread waiting for AUTOINC_LOCK for the table
and it leads to deadlock. Deadlock is happening because the count of
the nodes visited exceeds the threshold limit(10^6).

- Marking the subtree visited logic in the current deadlock search
algorithm having some issue respect to table level lock.

- While traversing the lock wait queue and if it reaches the current waiting
lock then we mark the subtree as visited.

- In row level lock, we are traversing from the head of the queue and eventually
we will reach the current waiting lock in the lock wait queue.

- But in table level lock, we are traversing from the tail of the queue,
we will never reach the current waiting lock in the lock wait queue.

Fix:
====

To fix visiting subtree logic for table level lock,
traverse from the head of the lock wait queue.

Reviewed-by: Debarun Banerjee<[email protected]>
RB: 12147

Author: Thirunarayanan

mysql-test/suite/innodb/r/innodb_deadlock_with_autoinc.result

@@ -0,0 +1,12 @@
+#
+# Bug #21983865  UNEXPECTED DEADLOCK WITH INNODB_AUTOINC_LOCK_MODE=0
+#
+create table t1(f1 int not null auto_increment primary key) engine=innodb;
+# Hold autoinc_lock on table t1 from connection con1
+set debug_sync='ib_after_row_insert SIGNAL others WAIT_FOR continue_others';
+insert into t1 values(NULL);
+# Create 40 connections and make it to wait for autoinc_lock on table t1.
+# Release the auto_inc lock on table t1 for connection con1
+set debug_sync='now SIGNAL continue_others';
+# Now all 40 connections can finish the insert operation on t1.
+drop table t1;

mysql-test/suite/innodb/t/innodb_deadlock_with_autoinc-master.opt

@@ -0,0 +1 @@
+--innodb-autoinc-lock-mode=0

mysql-test/suite/innodb/t/innodb_deadlock_with_autoinc.test

@@ -0,0 +1,47 @@
+--source include/have_debug.inc
+--source include/have_innodb.inc
+--source include/have_debug_sync.inc
+--source include/count_sessions.inc
+
+--echo #
+--echo # Bug #21983865  UNEXPECTED DEADLOCK WITH INNODB_AUTOINC_LOCK_MODE=0
+--echo #
+
+create table t1(f1 int not null auto_increment primary key) engine=innodb;
+
+--echo # Hold autoinc_lock on table t1 from connection con1
+connect (con1, localhost, root);
+set debug_sync='ib_after_row_insert SIGNAL others WAIT_FOR continue_others';
+--send insert into t1 values(NULL)
+
+connection default;
+--echo # Create 40 connections and make it to wait for autoinc_lock on table t1.
+--disable_query_log
+set debug_sync='now WAIT_FOR others';
+let $1=2;
+while ($1 < 40) {
+ connect (con$1,localhost,root);
+ --send insert into t1 values(NULL)
+ inc $1;
+ connection default;
+}
+
+connect (con40,localhost,root);
+--enable_query_log
+--echo # Release the auto_inc lock on table t1 for connection con1
+set debug_sync='now SIGNAL continue_others';
+
+--echo # Now all 40 connections can finish the insert operation on t1.
+let $1=1;
+connection default;
+disconnect con40;
+while ($1 < 40) {
+ connection con$1;
+ --reap
+ connection default;
+ disconnect con$1;
+ inc $1;
+}
+
+drop table t1;
+--source include/wait_until_count_sessions.inc

storage/innobase/lock/lock0lock.cc

@@ -3616,7 +3616,7 @@ lock_get_next_lock(
 			ut_ad(heap_no == ULINT_UNDEFINED);
 			ut_ad(lock_get_type_low(lock) == LOCK_TABLE);
 
-			lock = UT_LIST_GET_PREV(un_member.tab_lock.locks, lock);
+			lock = UT_LIST_GET_NEXT(un_member.tab_lock.locks, lock);
 		}
 	} while (lock != NULL
 		 && lock->trx->lock.deadlock_mark > ctx->mark_start);
@@ -3666,7 +3666,8 @@ lock_get_first_lock(
 	} else {
 		*heap_no = ULINT_UNDEFINED;
 		ut_ad(lock_get_type_low(lock) == LOCK_TABLE);
-		lock = UT_LIST_GET_PREV(un_member.tab_lock.locks, lock);
+		dict_table_t*   table = lock->un_member.tab_lock.table;
+		lock = UT_LIST_GET_FIRST(table->locks);
 	}
 
 	ut_a(lock != NULL);