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Date:   Wed, 17 Apr 2019 18:29:13 +0200
From:   Julian Wiedmann <jwi@...ux.ibm.com>
To:     David Miller <davem@...emloft.net>
Cc:     <netdev@...r.kernel.org>, <linux-s390@...r.kernel.org>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Stefan Raspl <raspl@...ux.ibm.com>,
        Ursula Braun <ubraun@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Julian Wiedmann <jwi@...ux.ibm.com>
Subject: [PATCH net] s390: ctcm: fix ctcm_new_device error return code

From: Arnd Bergmann <arnd@...db.de>

clang points out that the return code from this function is
undefined for one of the error paths:

../drivers/s390/net/ctcm_main.c:1595:7: warning: variable 'result' is used uninitialized whenever 'if' condition is true
      [-Wsometimes-uninitialized]
                if (priv->channel[direction] == NULL) {
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/s390/net/ctcm_main.c:1638:9: note: uninitialized use occurs here
        return result;
               ^~~~~~
../drivers/s390/net/ctcm_main.c:1595:3: note: remove the 'if' if its condition is always false
                if (priv->channel[direction] == NULL) {
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/s390/net/ctcm_main.c:1539:12: note: initialize the variable 'result' to silence this warning
        int result;
                  ^

Make it return -ENODEV here, as in the related failure cases.
gcc has a known bug in underreporting some of these warnings
when it has already eliminated the assignment of the return code
based on some earlier optimization step.

Reviewed-by: Nathan Chancellor <natechancellor@...il.com>
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Julian Wiedmann <jwi@...ux.ibm.com>
---
 drivers/s390/net/ctcm_main.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/s390/net/ctcm_main.c b/drivers/s390/net/ctcm_main.c
index 7617d21cb296..f63c5c871d3d 100644
--- a/drivers/s390/net/ctcm_main.c
+++ b/drivers/s390/net/ctcm_main.c
@@ -1595,6 +1595,7 @@ static int ctcm_new_device(struct ccwgroup_device *cgdev)
 		if (priv->channel[direction] == NULL) {
 			if (direction == CTCM_WRITE)
 				channel_free(priv->channel[CTCM_READ]);
+			result = -ENODEV;
 			goto out_dev;
 		}
 		priv->channel[direction]->netdev = dev;
-- 
2.16.4

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