diff mbox

[tip/core/rcu,10/13] mac80211: Apply rcu_access_pointer() to avoid sparse false positive

Message ID 1380072916-31557-10-git-send-email-paulmck@linux.vnet.ibm.com (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

Paul E. McKenney Sept. 25, 2013, 1:35 a.m. UTC 
From: "Paul E. McKenney" <paulmck@linux.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 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 <fengguang.wu@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
---
 net/mac80211/sta_info.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox

Patch

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) {
 		rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)],
-				   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,
 					lockdep_is_held(&local->sta_mtx));
 	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;
 	}