From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758515Ab3IYBjG (ORCPT ); Tue, 24 Sep 2013 21:39:06 -0400 Received: from e34.co.us.ibm.com ([32.97.110.152]:39494 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758363Ab3IYBf1 (ORCPT ); Tue, 24 Sep 2013 21:35:27 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, "Paul E. McKenney" , Stephen Hemminger , "David S. Miller" , bridge@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH tip/core/rcu 03/13] bridge: Apply rcu_access_pointer() to avoid sparse false positive Date: Tue, 24 Sep 2013 18:35:06 -0700 Message-Id: <1380072916-31557-3-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1380072916-31557-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20130925013451.GA31260@linux.vnet.ibm.com> <1380072916-31557-1-git-send-email-paulmck@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13092501-1542-0000-0000-000001B89651 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 br_multicast_del_pg() and br_multicast_new_port_group() 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 these false positives by laundering the pointers using rcu_access_pointer() as suggested by Josh Triplett. Reported-by: kbuild test robot Signed-off-by: Paul E. McKenney Cc: Stephen Hemminger Cc: "David S. Miller" Cc: bridge@lists.linux-foundation.org Cc: netdev@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 d1c5786..314c81c 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