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Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI Cc: Arnd Bergmann , stable@vger.kernel.org, Martin Sebor , David Ahern , Matthias Schiffer , Nicolas Dichtel , WANG Cong , Eric Dumazet , Craig Gallek , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] ipv6 sit: work around bogus gcc-8 -Wrestrict warning Date: Thu, 22 Feb 2018 16:55:34 +0100 Message-Id: <20180222155546.1747665-1-arnd@arndb.de> X-Mailer: git-send-email 2.9.0 X-Provags-ID: V03:K0:M8MVWfIicySQgoVUzu8cEuhR+hO9Q7VirmWjKHNEU4J74FhycuE t4g0us61p/wrPXGsQ2/cX1hBAW38P167jcYbx8nbQiD5ivyOVugDcX1aco4r0P9GFsZCxYz EMpHQVyRK6PlbaJMowDlRlEqQS/1R9CX/qGO9bodlEP9GNUhrVQhK6Ie7zLEtR4dlRDMEzw hCpLhXB6VU9p4caJnJFhA== X-UI-Out-Filterresults: notjunk:1;V01:K0:sA40HkS2yWM=:KGJ7CgKZCPvOWw1hqI0tD5 SeicW1Wp2ssaB52zpXFkoW8X2JUHJnA/52a+pWbaweM7ocSQts5oG3gyHwT3qXXtS2E+LTYFl gapm2Bl7Njn37uTuIpD2b0nY7d10p5ti0vrqEfJlMeFxdRJ/wLPYJ/O2jr1I5JrnDWI6yITEr G8DVLWxPzrNEmwtGxA7wCYffy49UCxeNt0pRXvH7UcnHSlmd8lYTCvx6xPPA4xP6rhKO8eYpW 0uMTS+qseMy6w1HNt2rT010cO47x80mD3D1SevlzSPizN7K0PBCEbjmaz9Egy1Cc0RKxbndvA j52+0tmF4ZzKLy6j8H161RwFLt1nY8RcTIZyoPZJHjRmiFn7S/9aRjM5aGnEVdkIC+veCXNTi vmqLv/Doh7e3+Vqh1QoBrpVon7QpHIIyJI6zlQheRvJGk4NVxhAlWLlwPoXfCC0jWyOM7v/9o o0fdsHOC7HEJk6RyWIg7hTL/KTnJ3X6Oc8g6FXmeul965opVzj3rBj0aoj3wIaaZ9ybzE1lUr 7jQGQuveZpG5Bq25sx2lO4SB0nQ2MAgl0Me16dmsuw3cCVnAme7v7126Deq3PrwmlB/8hDUGS 4l4oq7czdGgJfmDwHJliSAzSAxyyLJIfmhxVamYp8QcXAMx9NoRzZ37nnd9oIU+QTCP8JlfOC yjXxrIGWEvYhMoGDzUgGe6O1Uo05I/gkbdssyyu5W3Qlpco2AQ7wPo80cWPDcI7F6T7L2BNnK ICZt4sfpWkuz1qeSRtsdhWQylE8MkCrLqVMLag== Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: gcc-8 has a new warning that detects overlapping input and output arguments in memcpy(). It triggers for sit_init_net() calling ipip6_tunnel_clone_6rd(), which is actually correct: net/ipv6/sit.c: In function 'sit_init_net': net/ipv6/sit.c:192:3: error: 'memcpy' source argument is the same as destination [-Werror=restrict] The problem here is that the logic detecting the memcpy() arguments finds them to be the same, but the conditional that tests for the input and output of ipip6_tunnel_clone_6rd() to be identical is not a compile-time constant. We know that netdev_priv(t->dev) is the same as t for a tunnel device, and comparing "dev" directly here lets the compiler figure out as well that 'dev == sitn->fb_tunnel_dev' when called from sit_init_net(), so it no longer warns. This code is old, so Cc stable to make sure that we don't get the warning for older kernels built with new gcc. Cc: stable@vger.kernel.org Cc: Martin Sebor Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83456 Signed-off-by: Arnd Bergmann --- net/ipv6/sit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index 3873d3877135..3a1775a62973 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -182,7 +182,7 @@ static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn) #ifdef CONFIG_IPV6_SIT_6RD struct ip_tunnel *t = netdev_priv(dev); - if (t->dev == sitn->fb_tunnel_dev) { + if (dev == sitn->fb_tunnel_dev) { ipv6_addr_set(&t->ip6rd.prefix, htonl(0x20020000), 0, 0, 0); t->ip6rd.relay_prefix = 0; t->ip6rd.prefixlen = 16; -- 2.9.0