[PATCH 4.19 33/37] scsi: core: Fix shost->cmd_per_lun calculation in scsi_add_host_with_dma()

Greg Kroah-Hartman
2021-10-25T19:29:09Z

From: Dexuan Cui <decui@microsoft.com>

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@microsoft.com
Fixes: ea2f0f77538c ("scsi: core: Cap scsi_host cmd_per_lun at can_queue")
Cc: stable@vger.kernel.org
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/scsi/hosts.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -218,7 +218,8 @@ 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);