Hi, Eric During code review, I notice we might have some problem after we go lockless for the fast path in act_mirred.
That is, what prevents us from the following possible race condition? change a standalone action with tcf_mirred_init(): // search for an existing action in hash // found it and got struct tcf_common m = to_mirred(a); m->tcf_action = parm->action; // Interrupted by BH tcf_mirred() jumps in: rcu_read_lock() retval = READ_ONCE(m->tcf_action); if (m->tcfm_eaction != TCA_EGRESS_MIRROR) .... rcu_unread_lock() now go back to tcf_mirred_init(): m->tcfm_eaction = parm->eaction; .... IOW, the fast path could read a partially written change which could be a problem? We need to allocate a new copy and then replace the old one with it via RCU, don't we? I can work on some patches, I want to make sure I don't miss anything here. Thanks!
