From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932806Ab3IYBfj (ORCPT ); Tue, 24 Sep 2013 21:35:39 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:53940 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758384Ab3IYBf2 (ORCPT ); Tue, 24 Sep 2013 21:35:28 -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" , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , netdev@vger.kernel.org Subject: [PATCH tip/core/rcu 06/13] ipv4/ip_socketglue: Apply rcu_access_pointer() to avoid sparse false positive Date: Tue, 24 Sep 2013 18:35:09 -0700 Message-Id: <1380072916-31557-6-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: 13092501-9332-0000-0000-0000018760BC 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 use in ip_ra_control() is legitimate: It 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 Signed-off-by: Paul E. McKenney Cc: "David S. Miller" Cc: Alexey Kuznetsov Cc: James Morris Cc: Hideaki YOSHIFUJI Cc: Patrick McHardy Cc: netdev@vger.kernel.org --- net/ipv4/ip_sockglue.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index d9c4f11..d328f15 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -269,7 +269,7 @@ int ip_ra_control(struct sock *sk, unsigned char on, } /* dont let ip_call_ra_chain() use sk again */ ra->sk = NULL; - rcu_assign_pointer(*rap, ra->next); + rcu_assign_pointer(*rap, rcu_access_pointer(ra->next)); spin_unlock_bh(&ip_ra_lock); if (ra->destructor) -- 1.8.1.5