lkml.org 
[lkml]   [2017]   [Aug]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[net-next PATCH] ipv6: fix false-postive maybe-uninitialized warning
Date
Adding a lock around one of the assignments prevents gcc from
tracking the state of the local 'fibmatch' variable, so it can no
longer prove that 'dst' is always initialized, leading to a bogus
warning:

net/ipv6/route.c: In function 'inet6_rtm_getroute':
net/ipv6/route.c:3659:2: error: 'dst' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This moves the other assignment into the same lock to shut up the
warning.

Fixes: 121622dba8da ("ipv6: route: make rtm_getroute not assume rtnl is locked")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
net/ipv6/route.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

This kind of warning involving an unlock between variable initialization
and use is relatively frequent for false-positives. I should try to
seek clarification from the gcc developers on whether this can be
improved.

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index dc021ed6dd37..bec12ae3e6b7 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3624,6 +3624,8 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,

if (!fibmatch)
dst = ip6_route_input_lookup(net, dev, &fl6, flags);
+ else
+ dst = ip6_route_lookup(net, &fl6, 0);

rcu_read_unlock();
} else {
@@ -3631,10 +3633,10 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,

if (!fibmatch)
dst = ip6_route_output(net, NULL, &fl6);
+ else
+ dst = ip6_route_lookup(net, &fl6, 0);
}

- if (fibmatch)
- dst = ip6_route_lookup(net, &fl6, 0);

rt = container_of(dst, struct rt6_info, dst);
if (rt->dst.error) {
--
2.9.0
\
 
 \ /
  Last update: 2017-08-18 13:35    [W:0.035 / U:2.816 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site