Before calling blk_mq_map_queues(), the mq_map and nr_queues belonging
to "struct blk_mq_queue_map" must be a vaild value.

If nr_queues is set to 0, the system may encounter the "divide zero"
depending on the type of architecture.

    blk_mq_map_queues() -> queue_index()

Signed-off-by: Jinyoung Choi <j-young.choi@samsung.com>
---
 drivers/scsi/ufs/ufshcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 41d85b69fa50..36c5ca62ae0c 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -2674,21 +2674,21 @@ static int ufshcd_map_queues(struct Scsi_Host *shost)
 	for (i = 0; i < shost->nr_maps; i++) {
 		struct blk_mq_queue_map *map = &shost->tag_set.map[i];
 
 		switch (i) {
 		case HCTX_TYPE_DEFAULT:
 		case HCTX_TYPE_POLL:
 			map->nr_queues = 1;
 			break;
 		case HCTX_TYPE_READ:
 			map->nr_queues = 0;
-			break;
+			continue;
 		default:
 			WARN_ON_ONCE(true);
 		}
 		map->queue_offset = 0;
 		ret = blk_mq_map_queues(map);
 		WARN_ON_ONCE(ret);
 	}
 
 	return 0;
 }
-- 
2.25.1

On 2/14/22 02:33, Jinyoung CHOI wrote:
> Before calling blk_mq_map_queues(), the mq_map and nr_queues belonging
> to "struct blk_mq_queue_map" must be a vaild value.
                                     ^^   ^^^^^
                                   have   valid

> If nr_queues is set to 0, the system may encounter the "divide zero"
> depending on the type of architecture.

Anyway:

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

>On 2/14/22 02:33, Jinyoung CHOI wrote:
>> Before calling blk_mq_map_queues(), the mq_map and nr_queues belonging
>> to "struct blk_mq_queue_map" must be a vaild value.
>                                     ^^   ^^^^^
>                                   have   valid
> 
>> If nr_queues is set to 0, the system may encounter the "divide zero"
>> depending on the type of architecture.
> 
>Anyway:
>
>Reviewed-by: Bart Van Assche <bvanassche@acm.org>

Hi, Bart.

Thanks for your review.
I will be careful of typo. :)

Best Regards,
Jinyoung Choi

On Mon, 14 Feb 2022 19:33:52 +0900, Jinyoung CHOI wrote:

> Before calling blk_mq_map_queues(), the mq_map and nr_queues belonging
> to "struct blk_mq_queue_map" must be a vaild value.
> 
> If nr_queues is set to 0, the system may encounter the "divide zero"
> depending on the type of architecture.
> 
>     blk_mq_map_queues() -> queue_index()
> 
> [...]

Applied to 5.17/scsi-fixes, thanks!

[1/1] scsi: ufs: Fix divide zero case in ufshcd_map_queues()
      https://git.kernel.org/mkp/scsi/c/10af11564617

-- 
Martin K. Petersen	Oracle Linux Engineering