linux-kernel - [PATCH] netfilter: nf_nat_h323: fix logical-not-parentheses warning

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Message-Id: <20170731183949.73763-1-ndesaulniers@google.com>
Date:   Mon, 31 Jul 2017 11:39:49 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     mka@...omium.org, lorenzo@...gle.com,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] netfilter: nf_nat_h323: fix logical-not-parentheses warning

Clang produces the following warning:

net/ipv4/netfilter/nf_nat_h323.c:553:6: error:
logical not is only applied to the left hand side of this comparison
  [-Werror,-Wlogical-not-parentheses]
if (!set_h225_addr(skb, protoff, data, dataoff, taddr,
    ^
add parentheses after the '!' to evaluate the comparison first
add parentheses around left hand side expression to silence this warning

There's not necessarily a bug here, but it's cleaner to use the form:

if (x != 0)

rather than:

if (!x == 0)

Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
---
Also, it's even cleaner to use the form:

if (x)

but then if the return codes change from treating 0 as success (unlikely),
then all call sites must be updated.

I'm happy to send v2 that changes to that form, and updates the other call
sites to be:

if (set_h225_addr())
  handle_failures()
else
  handle_success()

 net/ipv4/netfilter/nf_nat_h323.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/netfilter/nf_nat_h323.c b/net/ipv4/netfilter/nf_nat_h323.c
index 574f7ebba0b6..d8fb251fa6e3 100644
--- a/net/ipv4/netfilter/nf_nat_h323.c
+++ b/net/ipv4/netfilter/nf_nat_h323.c
@@ -550,9 +550,9 @@ static int nat_callforwarding(struct sk_buff *skb, struct nf_conn *ct,
 	}
 
 	/* Modify signal */
-	if (!set_h225_addr(skb, protoff, data, dataoff, taddr,
-			   &ct->tuplehash[!dir].tuple.dst.u3,
-			   htons(nated_port)) == 0) {
+	if (set_h225_addr(skb, protoff, data, dataoff, taddr,
+			  &ct->tuplehash[!dir].tuple.dst.u3,
+			  htons(nated_port)) != 0) {
 		nf_ct_unexpect_related(exp);
 		return -1;
 	}
-- 
2.14.0.rc0.400.g1c36432dff-goog