From b8d576d087abbaf8075adb8936d505d0afd872f2 Mon Sep 17 00:00:00 2001
From: "heikki@hundin.mysql.fi" <>
Date: Mon, 27 Dec 2004 17:15:38 +0200
Subject: [PATCH] row0ins.c:   Fix bug: if we dropped a table where an INSERT
 was waiting for a lock to check a FOREIGN KEY constraint, then an assertion
 would fail in lock_reset_all_on_table(), since that operation assumes no
 waiting locks on the table or its records row0mysql.c:   Fix bug: InnoDB
 failed to drop a table in the background drop queue if the table was
 referenced by a foreign key constraint

---
 innobase/row/row0ins.c   | 26 ++++++++++++++++++++++++++
 innobase/row/row0mysql.c | 16 +++++++++++-----
 2 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/innobase/row/row0ins.c b/innobase/row/row0ins.c
index b9f860903cb..60dbf059673 100644
--- a/innobase/row/row0ins.c
+++ b/innobase/row/row0ins.c
@@ -1373,8 +1373,34 @@ row_ins_check_foreign_constraints(
 				row_mysql_freeze_data_dictionary(trx);
 			}
 
+			if (foreign->referenced_table) {
+				mutex_enter(&(dict_sys->mutex));
+
+				(foreign->referenced_table
+					->n_foreign_key_checks_running)++;
+
+				mutex_exit(&(dict_sys->mutex));
+			}
+
+			/* NOTE that if the thread ends up waiting for a lock
+			we will release dict_operation_lock temporarily!
+			But the counter on the table protects the referenced
+			table from being dropped while the check is running. */
+
 			err = row_ins_check_foreign_constraint(TRUE, foreign,
 						table, entry, thr);
+
+			if (foreign->referenced_table) {
+				mutex_enter(&(dict_sys->mutex));
+
+				ut_a(foreign->referenced_table
+					->n_foreign_key_checks_running > 0);
+				(foreign->referenced_table
+					->n_foreign_key_checks_running)--;
+
+				mutex_exit(&(dict_sys->mutex));
+			}
+
 			if (got_s_lock) {
 				row_mysql_unfreeze_data_dictionary(trx);
 			}
diff --git a/innobase/row/row0mysql.c b/innobase/row/row0mysql.c
index 2e8f7121d2c..ad5efc160c8 100644
--- a/innobase/row/row0mysql.c
+++ b/innobase/row/row0mysql.c
@@ -1761,6 +1761,12 @@ row_drop_table_for_mysql_in_background(
 
 	trx = trx_allocate_for_background();
 
+	/* If the original transaction was dropping a table referenced by
+	foreign keys, we must set the following to be able to drop the
+	table: */
+
+	trx->check_foreigns = FALSE;
+
 /*	fputs("InnoDB: Error: Dropping table ", stderr);
 	ut_print_name(stderr, name);
 	fputs(" in background drop list\n", stderr); */
@@ -1834,16 +1840,16 @@ loop:
 
 	        goto already_dropped;
 	}
-
-	if (table->n_mysql_handles_opened > 0
-				|| table->n_foreign_key_checks_running > 0) {
+							
+	if (DB_SUCCESS != row_drop_table_for_mysql_in_background(
+							drop->table_name)) {
+		/* If the DROP fails for some table, we return, and let the
+		main thread retry later */
 
 		return(n_tables + n_tables_dropped);
 	}
 
 	n_tables_dropped++;
-							
-	row_drop_table_for_mysql_in_background(drop->table_name);
 
 already_dropped:
 	mutex_enter(&kernel_mutex);