Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756546Ab3JIVaF (ORCPT ); Wed, 9 Oct 2013 17:30:05 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:45754 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756279Ab3JIV36 (ORCPT ); Wed, 9 Oct 2013 17:29:58 -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 v2 tip/core/rcu 11/13] bridge/br_mdb: Apply rcu_access_pointer() to avoid sparse false positive Date: Wed, 9 Oct 2013 14:29:44 -0700 Message-Id: <1381354186-16285-11-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1381354186-16285-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20131009212920.GA15413@linux.vnet.ibm.com> <1381354186-16285-1-git-send-email-paulmck@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13100921-9332-0000-0000-000001B53D94 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1673 Lines: 43 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 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 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_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..3184c8812b49 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); + 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); -- 1.8.1.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/