On May 15, 2012, at 10:29 AM, Ben Pfaff wrote: >>>> Do you think it's worth having the total be a #define, and then do a >>>> build-time assertion that the total value is less than >>>> ODPUTIL_FLOW_KEY_BYTES? >>> >>> Can you explain how that would be different? >> >> Right now, we have a chart that maps out the total number of bytes >> needed to represent the largest flow. When updating that chart it's >> pretty obvious that the "total" field at the bottom needs to be >> updated. I feel like we've had issues in the past where "total" was >> updated, but ODPUTIL_FLOW_KEY_BYTES was not. This would serve as a >> reminder. It's pretty unlikely to occur, but I was thinking it would >> be a good sanity-check. We could also mandate a certain amount a >> slack. However, if you think it's unnecessary, I'm fine not adding >> one, too. > > Mostly I don't understand what you envision the code or comment looking > like. Can you show me?
I was thinking of something like the following: -=-=-=-=-=-=-=-=-=-=- * struct pad nl hdr total * ------ --- ------ ----- * OVS_KEY_ATTR_PRIORITY 4 -- 4 8 ... * OVS_KEY_ATTR_ND 28 -- 4 32 * -------------------------------------------------*/ #define ODP_FLOW_KEY_MAX_TOTAL 156 /* We include some slack space in case the calculation isn't quite right or we * add another field and forget to adjust this value. */ #define ODPUTIL_FLOW_KEY_BYTES 200 BUILD_ASSERT_DECL(ODP_FLOW_KEY_MAX_TOTAL < ODPUTIL_FLOW_KEY_BYTES) -=-=-=-=-=-=-=-=-=-=- However, ODPUTIL_FLOW_KEY_BYTES is defined pretty close to "total", so it's probably pointless. I'll drop this, unless you've suddenly fallen in love with the idea. :-) --Justin _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
