[PATCH 1/1] block: nbd: fix bugs in nbd_init

[Pan Bian]

Fix bug https://bugzilla.kernel.org/show_bug.cgi?id=188441. Fix 3 bugs
in function nbd_init: (1) set error code (-ENOMEM) when the call to
alloc_disk() fails; (2) function blk_mq_init_queue() returns an
ERR_PTR pointer rather than NULL on failures, so use IS_ERR to check the
return value; (3) set error code on the branch that blk_mq_init_queue()
returns an invalid pointer.

Signed-off-by: Pan Bian <bianpan2016@xxxxxxx>
---
 drivers/block/nbd.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 7a10487..200e899 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -930,8 +930,10 @@ static int __init nbd_init(void)
 
 	for (i = 0; i < nbds_max; i++) {
 		struct gendisk *disk = alloc_disk(1 << part_shift);
-		if (!disk)
+		if (!disk) {
+			err = -ENOMEM;
 			goto out;
+		}
 		nbd_dev[i].disk = disk;
 
 		nbd_dev[i].tag_set.ops = &nbd_mq_ops;
@@ -955,7 +957,8 @@ static int __init nbd_init(void)
 		 * These structs are big so we dynamically allocate them.
 		 */
 		disk->queue = blk_mq_init_queue(&nbd_dev[i].tag_set);
-		if (!disk->queue) {
+		if (IS_ERR(disk->queue)) {
+			err = PTR_ERR(disk->queue);
 			blk_mq_free_tag_set(&nbd_dev[i].tag_set);
 			put_disk(disk);
 			goto out;
-- 
1.9.1