Bug #14100254 65389: MVCC IS BROKEN WITH IMPLICIT LOCK

rb://1088
approved by: Marko Makela

This bug was introduced in early stages of plugin. We were not
checking for an implicit lock on sec index rec for trx_id that is
stamped on current version of the clust_index in case where the
clust_index has a previous delete marked version.

storage/innodb_plugin/row/row0vers.c

@@ -208,18 +208,6 @@ row_vers_impl_x_locked_off_kernel(
 		vers_del = rec_get_deleted_flag(prev_version, comp);
 		prev_trx_id = row_get_rec_trx_id(prev_version, clust_index,
 						 clust_offsets);
-
-		/* If the trx_id and prev_trx_id are different and if
-		the prev_version is marked deleted then the
-		prev_trx_id must have already committed for the trx_id
-		to be able to modify the row. Therefore, prev_trx_id
-		cannot hold any implicit lock. */
-		if (vers_del && 0 != ut_dulint_cmp(trx_id, prev_trx_id)) {
-
-			mutex_enter(&kernel_mutex);
-			break;
-		}
-
 		/* The stack of versions is locked by mtr.  Thus, it
 		is safe to fetch the prefixes for externally stored
 		columns. */