linux-kernel - [PATCH] scsi: srp_transport: Fix 'always false comparison' in srp_tmo

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Message-Id: <1485429447-19103-1-git-send-email-augustocaringi@gmail.com>
Date:   Thu, 26 Jan 2017 11:17:16 +0000
From:   Augusto Mecking Caringi <augustocaringi@...il.com>
To:     "James E . J . Bottomley" <jejb@...ux.vnet.ibm.com>
Cc:     Augusto Mecking Caringi <augustocaringi@...il.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "Ewan D. Milne" <emilne@...hat.com>,
        Bart Van Assche <bart.vanassche@...disk.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] scsi: srp_transport: Fix 'always false comparison' in srp_tmo_valid()

In a 64bit system (where long is 64bit wide), even dividing LONG_MAX by
HZ will always be bigger than the max value that an int variable can
hold.

This has been detected by building the driver with W=1:

drivers/scsi/scsi_transport_srp.c: In function ‘srp_tmo_valid’:
drivers/scsi/scsi_transport_srp.c:92:19: warning: comparison is always
false due to limited range of data type [-Wtype-limits]
if (dev_loss_tmo >= LONG_MAX / HZ)
                   ^

Signed-off-by: Augusto Mecking Caringi <augustocaringi@...il.com>
---
 drivers/scsi/scsi_transport_srp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
index b87a786..d8c83f4 100644
--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -89,7 +89,7 @@ int srp_tmo_valid(int reconnect_delay, int fast_io_fail_tmo, int dev_loss_tmo)
 	if (fast_io_fail_tmo < 0 &&
 	    dev_loss_tmo > SCSI_DEVICE_BLOCK_MAX_TIMEOUT)
 		return -EINVAL;
-	if (dev_loss_tmo >= LONG_MAX / HZ)
+	if (dev_loss_tmo >= INT_MAX / HZ)
 		return -EINVAL;
 	if (fast_io_fail_tmo >= 0 && dev_loss_tmo >= 0 &&
 	    fast_io_fail_tmo >= dev_loss_tmo)
-- 
2.7.4