[Bridge] [PATCH v2 tip/core/rcu 03/13] bridge: Apply rcu_access_pointer() to avoid sparse false positive
Paul E. McKenney
paulmck at linux.vnet.ibm.com
Wed Oct 9 21:29:36 UTC 2013
From: "Paul E. McKenney" <paulmck at 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
br_multicast_del_pg() and br_multicast_new_port_group() are 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 rcu_access_pointer() as suggested by Josh Triplett.
Reported-by: kbuild test robot <fengguang.wu at intel.com>
Signed-off-by: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
Cc: Stephen Hemminger <stephen at networkplumber.org>
Cc: "David S. Miller" <davem at davemloft.net>
Cc: bridge at lists.linux-foundation.org
Cc: netdev at vger.kernel.org
---
net/bridge/br_multicast.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index d1c578630678..314c81cc5855 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -267,7 +267,7 @@ static void br_multicast_del_pg(struct net_bridge *br,
if (p != pg)
continue;
- rcu_assign_pointer(*pp, p->next);
+ rcu_assign_pointer(*pp, rcu_access_pointer(p->next));
hlist_del_init(&p->mglist);
del_timer(&p->timer);
call_rcu_bh(&p->rcu, br_multicast_free_pg);
@@ -646,7 +646,7 @@ struct net_bridge_port_group *br_multicast_new_port_group(
p->addr = *group;
p->port = port;
p->state = state;
- rcu_assign_pointer(p->next, next);
+ rcu_assign_pointer(p->next, rcu_access_pointer(next));
hlist_add_head(&p->mglist, &port->mglist);
setup_timer(&p->timer, br_multicast_port_group_expired,
(unsigned long)p);
--
1.8.1.5
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