Dan reported this:
The patch 2984c8684f96: "nullb: factor disk parameters" from Aug 14,
2017, leads to the following Smatch complaint:
drivers/block/null_blk.c:1759 null_init_tag_set()
error: we previously assumed 'nullb' could be null (see line
1750)
1755 set->cmd_size = sizeof(struct nullb_cmd);
1756 set->flags = BLK_MQ_F_SHOULD_MERGE;
1757 set->driver_data = NULL;
1758
1759 if (nullb->dev->blocking)
^^^^^^^^^^^^^^^^^^^^
And an unchecked dereference.
nullb could be NULL here.
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxx>
---
drivers/block/null_blk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 2032360..4d328e3 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -1756,7 +1756,7 @@ static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set)
set->flags = BLK_MQ_F_SHOULD_MERGE;
set->driver_data = NULL;
- if (nullb->dev->blocking)
+ if ((nullb && nullb->dev->blocking) || g_blocking)
set->flags |= BLK_MQ_F_BLOCKING;
return blk_mq_alloc_tag_set(set);
--
2.9.5
