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Date:	Tue, 24 Sep 2013 18:35:09 -0700
From:	"Paul E. McKenney" <>
Cc:,,,,,,,,,,,,,,, "Paul E. McKenney" <>,
	"David S. Miller" <>,
	Alexey Kuznetsov <>,
	James Morris <>,
	Hideaki YOSHIFUJI <>,
	Patrick McHardy <>,
Subject: [PATCH tip/core/rcu 06/13] ipv4/ip_socketglue: Apply rcu_access_pointer() to avoid sparse false positive

From: "Paul E. McKenney" <>

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
ip_ra_control() 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 <>
Signed-off-by: Paul E. McKenney <>
Cc: "David S. Miller" <>
Cc: Alexey Kuznetsov <>
Cc: James Morris <>
Cc: Hideaki YOSHIFUJI <>
Cc: Patrick McHardy <>
 net/ipv4/ip_sockglue.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index d9c4f11..d328f15 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -269,7 +269,7 @@ int ip_ra_control(struct sock *sk, unsigned char on,
 			/* dont let ip_call_ra_chain() use sk again */
 			ra->sk = NULL;
-			rcu_assign_pointer(*rap, ra->next);
+			rcu_assign_pointer(*rap, rcu_access_pointer(ra->next));
 			if (ra->destructor)

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