From: George Spelvin <lkml@sdf.org>
Date: Fri, 3 Jul 2020 15:19:57 +0200
Subject: scsi: zfcp: Use prandom_u32_max() for backoff
Git-commit: 0cd0e57ec858edda580fb90b53df5269216b61b2
Patch-mainline: v5.9-rc1
References: jsc#SLE-15871 bsc#1176961 LTC#187760

We don't need crypto-grade random numbers for randomized backoffs.  Instead
use prandom_u32_max(ep_ro) which generates a pseudo-random number uniformly
distributed in the interval [0, ep_ro).

Link: https://lore.kernel.org/r/8fc7c4c4069ff1783f4a9ccd84a923f581a09ec5.1593780621.git.bblock@linux.ibm.com
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: George Spelvin <lkml@sdf.org>
Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/scsi/zfcp_fc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/s390/scsi/zfcp_fc.c
+++ b/drivers/s390/scsi/zfcp_fc.c
@@ -48,7 +48,7 @@ unsigned int zfcp_fc_port_scan_backoff(v
 {
 	if (!port_scan_backoff)
 		return 0;
-	return get_random_int() % port_scan_backoff;
+	return prandom_u32_max(port_scan_backoff);
 }
 
 static void zfcp_fc_port_scan_time(struct zfcp_adapter *adapter)