branches/zip: Fix a regression introduced by the fix for bug#26316. We check

whether a transaction holds any AUTOINC locks before we acquire the kernel
mutex and release those locks.

Fix for rb://153. Approved by Marko.

include/lock0lock.h

@@ -630,6 +630,14 @@ lock_number_of_rows_locked(
 /*=======================*/
 	trx_t*	trx);	/*!< in: transaction */
 /*******************************************************************//**
+Check if a transaction holds any autoinc locks.
+@return TRUE if the transaction holds any AUTOINC locks. */
+UNIV_INTERN
+ibool
+lock_trx_holds_autoinc_locks(
+/*=========================*/
+	const trx_t*	trx);		/*!< in: transaction */
+/*******************************************************************//**
 Release all the transaction's autoinc locks. */
 UNIV_INTERN
 void

include/row0mysql.h

@@ -177,7 +177,9 @@ row_update_prebuilt_trx(
 					in MySQL handle */
 	trx_t*		trx);		/*!< in: transaction handle */
 /*********************************************************************//**
-Unlocks AUTO_INC type locks that were possibly reserved by a trx. */
+Unlocks AUTO_INC type locks that were possibly reserved by a trx. This
+function should be called at the the end of an SQL statement, by the
+connection thread that owns the transaction (trx->mysql_thd). */
 UNIV_INTERN
 void
 row_unlock_table_autoinc_for_mysql(

lock/lock0lock.c

@@ -5371,6 +5371,20 @@ lock_release_autoinc_last_lock(
 	lock_table_dequeue(lock);
 }
 
+/*******************************************************************//**
+Check if a transaction holds any autoinc locks. 
+@return TRUE if the transaction holds any AUTOINC locks. */
+UNIV_INTERN
+ibool
+lock_trx_holds_autoinc_locks(
+/*=========================*/
+	const trx_t*	trx)		/*!< in: transaction */
+{
+	ut_a(trx->autoinc_locks != NULL);
+
+	return(!ib_vector_is_empty(trx->autoinc_locks));
+}
+
 /*******************************************************************//**
 Release all the transaction's autoinc locks. */
 UNIV_INTERN

row/row0mysql.c

@@ -866,18 +866,22 @@ row_update_statistics_if_needed(
 }
 
 /*********************************************************************//**
-Unlocks AUTO_INC type locks that were possibly reserved by a trx. */
+Unlocks AUTO_INC type locks that were possibly reserved by a trx. This
+function should be called at the the end of an SQL statement, by the
+connection thread that owns the transaction (trx->mysql_thd). */
 UNIV_INTERN
 void
 row_unlock_table_autoinc_for_mysql(
 /*===============================*/
 	trx_t*	trx)	/*!< in/out: transaction */
 {
-	mutex_enter(&kernel_mutex);
+	if (lock_trx_holds_autoinc_locks(trx)) {
+		mutex_enter(&kernel_mutex);
 
-	lock_release_autoinc_locks(trx);
+		lock_release_autoinc_locks(trx);
 
-	mutex_exit(&kernel_mutex);
+		mutex_exit(&kernel_mutex);
+	}
 }
 
 /*********************************************************************//**