On Fri, Sep 6, 2013 at 12:15 PM, Jesse Gross <[email protected]> wrote: > On Fri, Sep 6, 2013 at 11:39 AM, Pravin B Shelar <[email protected]> wrote: >> diff --git a/datapath/linux/compat/vxlan.c b/datapath/linux/compat/vxlan.c >> index db14f2f..3d4fec3 100644 >> --- a/datapath/linux/compat/vxlan.c >> +++ b/datapath/linux/compat/vxlan.c >> @@ -124,7 +124,8 @@ static int vxlan_udp_encap_recv(struct sock *sk, struct >> sk_buff *skb) >> if (iptunnel_pull_header(skb, VXLAN_HLEN, htons(ETH_P_TEB))) >> goto drop; >> >> - vs = vxlan_find_sock(sock_net(sk), inet_sport(sk)); >> + smp_read_barrier_depends(); >> + vs = (struct vxlan_sock *)sk->sk_user_data; >> if (!vs) >> goto drop; > > I think this is a correct backport of the upstream commit but this > part worries me a little bit because it is missing the ACCESS_ONCE > part of rcu_dereference. It's unlikely due to the code structure but > in theory the compiler could decide to omit 'vs' completely causing > refetches across the NULL check.
How compiler can omit 'vs' when NULL check has direct dependency on it? _______________________________________________ dev mailing list [email protected] http://openvswitch.org/mailman/listinfo/dev
