On 20/06/16 19:05, Lennert Buytenhek wrote:
From: David Barroso <dbarr...@fastly.com>When locally originated IP traffic hits a route that says to push MPLS labels, we'll get a call chain dst_output() -> lwtunnel_output() -> mpls_output() -> neigh_xmit() -> ___neigh_lookup_noref() where the last function in this chain accesses a RCU-bh protected struct neigh_table pointer without us ever having declared an RCU-bh read side critical section. As in case of locally originated IP traffic we'll be running in process context, with softirqs enabled, we can be preempted by a softirq at any time, and RCU-bh considers the completion of a softirq as signaling the end of any pending read-side critical sections, so if we do get a softirq here, we can end up with an unexpected RCU grace period and all the nastiness that that comes with. This patch makes neigh_xmit() take rcu_read_{,un}lock_bh() around the code that expects to be treated as an RCU-bh read side critical section. Signed-off-by: David Barroso <dbarr...@fastly.com> Signed-off-by: Lennert Buytenhek <lbuyten...@fastly.com>
LGTM too. Acked-by: Robert Shearman <rshea...@brocade.com>
