Bug#12606344 - ADD VALGRIND DIAGNOSTICS TO MTR_START, MTR_COMMIT

mtr_start(): Declare the mtr memory area uninitialized in Valgrind
before initializing the fields.

mtr_commit(): Declare everything uninitialized except
mtr->start_lsn, mtr->end_lsn and mtr->state.

storage/innobase/include/mtr0mtr.ic

@@ -37,6 +37,8 @@ mtr_start(
 /*======*/
 	mtr_t*	mtr)	/*!< out: mini-transaction */
 {
+	UNIV_MEM_INVALID(mtr, sizeof *mtr);
+
 	dyn_array_create(&(mtr->memo));
 	dyn_array_create(&(mtr->log));
 

storage/innobase/mtr/mtr0mtr.c

@@ -265,9 +265,20 @@ mtr_commit(
 	mtr_memo_pop_all(mtr);
 #endif /* !UNIV_HOTBACKUP */
 
-	ut_d(mtr->state = MTR_COMMITTED);
 	dyn_array_free(&(mtr->memo));
 	dyn_array_free(&(mtr->log));
+#ifdef UNIV_DEBUG_VALGRIND
+	/* Declare everything uninitialized except
+	mtr->start_lsn, mtr->end_lsn and mtr->state. */
+	{
+		ib_uint64_t	start_lsn	= mtr->start_lsn;
+		ib_uint64_t	end_lsn		= mtr->end_lsn;
+		UNIV_MEM_INVALID(mtr, sizeof *mtr);
+		mtr->start_lsn = start_lsn;
+		mtr->end_lsn = end_lsn;
+	}
+#endif /* UNIV_DEBUG_VALGRIND */
+	ut_d(mtr->state = MTR_COMMITTED);
 }
 
 #ifndef UNIV_HOTBACKUP