[PATCH 4.14 26/30] scsi: core: Fix shost->cmd_per_lun calculation in scsi_add_host_with_dma()

[Greg Kroah-Hartman]

From: Dexuan Cui <decui@xxxxxxxxxxxxx>

commit 50b6cb3516365cb69753b006be2b61c966b70588 upstream.

After commit ea2f0f77538c ("scsi: core: Cap scsi_host cmd_per_lun at
can_queue"), a 416-CPU VM running on Hyper-V hangs during boot because the
hv_storvsc driver sets scsi_driver.can_queue to an integer value that
exceeds SHRT_MAX, and hence scsi_add_host_with_dma() sets
shost->cmd_per_lun to a negative "short" value.

Use min_t(int, ...) to work around the issue.

Link: https://lore.kernel.org/r/20211008043546.6006-1-decui@xxxxxxxxxxxxx
Fixes: ea2f0f77538c ("scsi: core: Cap scsi_host cmd_per_lun at can_queue")
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Reviewed-by: John Garry <john.garry@xxxxxxxxxx>
Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/scsi/hosts.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -213,7 +213,8 @@ int scsi_add_host_with_dma(struct Scsi_H
 		goto fail;
 	}
 
-	shost->cmd_per_lun = min_t(short, shost->cmd_per_lun,
+	/* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */
+	shost->cmd_per_lun = min_t(int, shost->cmd_per_lun,
 				   shost->can_queue);
 
 	error = scsi_init_sense_cache(shost);