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Date:	Tue, 24 Sep 2013 18:35:13 -0700
From:	"Paul E. McKenney" <>
Cc:,,,,,,,,,,,,,,, "Paul E. McKenney" <>,
	"John W. Linville" <>,
	Johannes Berg <>,
	"David S. Miller" <>,,
Subject: [PATCH tip/core/rcu 10/13] mac80211: 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 uses in
sta_info_hash_del() are legitimate: They 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: "John W. Linville" <>
Cc: Johannes Berg <>
Cc: "David S. Miller" <>
 net/mac80211/sta_info.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index aeb967a..d18ab89 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -75,7 +75,7 @@ static int sta_info_hash_del(struct ieee80211_local *local,
 		return -ENOENT;
 	if (s == sta) {
-				   s->hnext);
+				   rcu_access_pointer(s->hnext));
 		return 0;
@@ -84,7 +84,7 @@ static int sta_info_hash_del(struct ieee80211_local *local,
 		s = rcu_dereference_protected(s->hnext,
 	if (rcu_access_pointer(s->hnext)) {
-		rcu_assign_pointer(s->hnext, sta->hnext);
+		rcu_assign_pointer(s->hnext, rcu_access_pointer(sta->hnext));
 		return 0;

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