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Message-Id: <1381354186-16285-7-git-send-email-paulmck@linux.vnet.ibm.com>
Date: Wed, 9 Oct 2013 14:29:40 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...nel.org, laijs@...fujitsu.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
peterz@...radead.org, rostedt@...dmis.org, dhowells@...hat.com,
edumazet@...gle.com, darren@...art.com, fweisbec@...il.com,
sbw@....edu, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
"David S. Miller" <davem@...emloft.net>,
Alexey Kuznetsov <kuznet@....inr.ac.ru>,
James Morris <jmorris@...ei.org>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
Patrick McHardy <kaber@...sh.net>, netdev@...r.kernel.org
Subject: [PATCH v2 tip/core/rcu 07/13] ipv6/ip6_tunnel: Apply rcu_access_pointer() to avoid sparse false positive
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
The sparse checking for rcu_assign_pointer() was recently upgraded
to reject non-__kernel address spaces. This also rejects __rcu,
which is almost always the right thing to do. However, the use in
ip6_tnl_unlink() is legitimate: It is assigning a pointer to an element
from an RCU-protected list, and all elements of this list are already
visible to caller.
This commit therefore silences this false positive by laundering the
pointer using rcu_access_pointer() as suggested by Josh Triplett.
Reported-by: kbuild test robot <fengguang.wu@...el.com>
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Alexey Kuznetsov <kuznet@....inr.ac.ru>
Cc: James Morris <jmorris@...ei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>
Cc: Patrick McHardy <kaber@...sh.net>
Cc: netdev@...r.kernel.org
---
net/ipv6/ip6_tunnel.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 61355f7f4da5..ecc0166e1a9c 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -245,7 +245,7 @@ ip6_tnl_unlink(struct ip6_tnl_net *ip6n, struct ip6_tnl *t)
(iter = rtnl_dereference(*tp)) != NULL;
tp = &iter->next) {
if (t == iter) {
- rcu_assign_pointer(*tp, t->next);
+ rcu_assign_pointer(*tp, rcu_access_pointer(t->next));
break;
}
}
--
1.8.1.5
--
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