block: mtip32xx: set error code on failure

Fix bug https://bugzilla.kernel.org/show_bug.cgi?id=188531. In function
mtip_block_initialize(), variable rv takes the return value, and its
value should be negative on errors. rv is initialized as 0 and is not
reset when the call to ida_pre_get() fails. So 0 may be returned.
The return value 0 indicates that there is no error, which may be
inconsistent with the execution status. This patch fixes the bug by
explicitly assigning -ENOMEM to rv on the branch that ida_pre_get()
fails.
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/mtip32xx/mtip32xx.c

@@ -3933,8 +3933,10 @@ static int mtip_block_initialize(struct driver_data *dd)
 
 	/* Generate the disk name, implemented same as in sd.c */
 	do {
-		if (!ida_pre_get(&rssd_index_ida, GFP_KERNEL))
+		if (!ida_pre_get(&rssd_index_ida, GFP_KERNEL)) {
+			rv = -ENOMEM;
 			goto ida_get_error;
+		}
 
 		spin_lock(&rssd_index_lock);
 		rv = ida_get_new(&rssd_index_ida, &index);