On Fri, Jun 17, 2016 at 2:24 PM, Eric Dumazet <eduma...@google.com> wrote: > Well, I added a READ_ONCE() to read tcf_action once. > > Adding rcu here would mean adding a pointer and extra cache line, to > deref the values. > > IMHO the race here has no effect . You either read the old or new value.
Sure, the point is we may read a new ->tcf_action and an old ->tcfm_eaction, this is what I am worrying. If that is not a good example, what about new ->tcf_action and ->tcfm_eaction, with an old ->tcfm_ifindex? > > If the packet is processed before or after the 'change' it would have > the same 'race' > Why? As long as the change is like a transaction, we are safe. > All these fields are integers, they never are 'partially written'. > > The only case m->tcfm_eaction could be read twice is in the error > path. Who cares ? This is not what I worry about. I guess you miss read eaction with action.
