On Mon, Oct 14, 2013 at 03:57:35PM -0700, Jarno Rajahalme wrote: > Since at the datapath interface we do not have set actions for > individual fields, but larger sets of fields for a given protocol > layer, the set action will in practice only ever apply to exactly > matched flows for the given protocol layer. For example, if the > reg_load changes the IP TTL, the corresponding datapath action will > rewrite also the IP addresses and TOS byte. Since these other field > values may not be explicity set, they depend on the incoming flow field > values, and are hence all of them are set in the wildcards masks, when > the action is committed to the datapath. For the rare case, where the > reg_load action does not actually change the value, and no other flow > field values are set (or loaded), the datapath action is skipped, and > no mask bits are set. Such a datapath flow should, however, be > dependent on the specific field value, so the corresponding wildcard > mask bits must be set, lest the datapath flow be applied to packets > containing some other value in the field and the field value remain > unchanged regardless of the incoming value. > > Signed-off-by: Jarno Rajahalme <[email protected]>
If I NXAST_REG_LOAD to, say, NXM_OF_TCP_SRC, then I agree that we need to un-wildcard the prerequisites (why not dl_type? I guess it is redundant, but it would make mf_force_prereqs() make more sense), and so this fixes a problem. But I don't think that it is sufficient, because if we actually emit an ODP action to set the TCP source port, then that action will also, unavoidably, set the TCP destination port too, and so we need to un-wildcard that. I guess that commit_odp_actions() and the functions it calls are the most logical place to do that, although currently they don't take a wc argument. _______________________________________________ dev mailing list [email protected] http://openvswitch.org/mailman/listinfo/dev
