linux-kernel - [PATCH] scsi: nsp32: fix logic bug in error handling

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Date:   Tue,  5 Sep 2017 09:51:29 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     GOTO Masanori <gotom@...ian.or.jp>,
        YOKOTA Hiroshi <yokota@...lab.is.tsukuba.ac.jp>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Hannes Reinecke <hare@...e.com>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] scsi: nsp32: fix logic bug in error handling

gcc-8 points out a logic error that has existed since the start
of the git history:

drivers/scsi/nsp32.c: In function 'nsp32_selection_autoscsi':
drivers/scsi/nsp32.c:607:27: error: bitwise comparison always evaluates to false [-Werror=tautological-compare]
  if(((phase & BUSMON_BSY) == 1) || (phase & BUSMON_SEL) == 1) {
                           ^~

Presumably the author intended to check if one of two bits was
set, so that's what I'm changing the code to. This will obviously
change the behavior of the code, hopefully to do the right thing,
but I have not tested this or checked if the new "(phase & BUSMON_BSY)
|| (phase & BUSMON_SEL)" condition should indeed be treated as a
fatal error.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/scsi/nsp32.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/nsp32.c b/drivers/scsi/nsp32.c
index 107e191bf023..8620ac5d6e41 100644
--- a/drivers/scsi/nsp32.c
+++ b/drivers/scsi/nsp32.c
@@ -604,7 +604,7 @@ static int nsp32_selection_autoscsi(struct scsi_cmnd *SCpnt)
 	 * check bus line
 	 */
 	phase = nsp32_read1(base, SCSI_BUS_MONITOR);
-	if(((phase & BUSMON_BSY) == 1) || (phase & BUSMON_SEL) == 1) {
+	if ((phase & BUSMON_BSY) || (phase & BUSMON_SEL)) {
 		nsp32_msg(KERN_WARNING, "bus busy");
 		SCpnt->result = DID_BUS_BUSY << 16;
 		status = 1;
-- 
2.9.0