From: "Paul E. McKenney" <paul...@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 use in
__br_mdb_del() is legitimate: They are 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 these false positives by laundering
the pointers using ACCESS_ONCE() as suggested by Eric Dumazet and Josh
Triplett.
Reported-by: kbuild test robot <fengguang...@intel.com>
Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Cc: Stephen Hemminger <step...@networkplumber.org>
Cc: "David S. Miller" <da...@davemloft.net>
Cc: bri...@lists.linux-foundation.org
Cc: net...@vger.kernel.org
---
net/bridge/br_mdb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 85a09bb5ca51..de7197ba8695 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -447,7 +447,7 @@ static int __br_mdb_del(struct net_bridge *br, struct
br_mdb_entry *entry)
if (p->port->state == BR_STATE_DISABLED)
goto unlock;
- rcu_assign_pointer(*pp, p->next);
+ ACCESS_ONCE(*pp) = p->next; /* OK: Both --rcu and visible. */
hlist_del_init(&p->mglist);
del_timer(&p->timer);
call_rcu_bh(&p->rcu, br_multicast_free_pg);
--
1.8.1.5
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