On Tue, Nov 28, 2017 at 3:08 PM, Willem de Bruijn <willemdebruijn.kernel@xxxxxxxxx> wrote: > On Tue, Nov 28, 2017 at 3:46 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote: >> On Tue, Nov 28, 2017 at 8:04 AM, Björn Töpel <bjorn.topel@xxxxxxxxx> wrote: >>> 2017-11-27 21:51 GMT+01:00 Arnd Bergmann <arnd@xxxxxxxx>: >>> [...] >>>>> There already is an effort to come up with a new AF_PACKET V4 [1]. >>>>> We should make sure that any new interface does not have the >>>>> Y2038/Y2106 issue. But, if a new version is being developed and >>>>> that subsumes all existing use cases, then there probably is no need >>>>> for another version that is a very small diff to V3. >>>> >>>> Ah, perfect, that's good timing. Adding Björn to Cc here. >>>> >>> >>> Unfortunately, for the Y2038/Y2106 cases, we'll be (as a result of >>> netdevconf discussions) moving the AF_PACKET V4 implementation to a >>> separate, new, address/packet family. >> >> Ok, I see. > > Does it matter whether the replacement is a new version or a > new packet family? It depends on whether the new packet family provides a superset of the AF_PACKET features or not. If we can expect that all users of AF_PACKET can migrate to the replacement over time, then doing it there is sufficient, otherwise adding 64-bit timestamps into AF_PACKET may be a better way to upgrade existing users. >>>>> If adding support for existing applications is useful, another approach >>>>> would be to add a new socket option that changes the semantics for >>>>> the two u32 fields in each of V1, V2 and V3 to hold nsec. Add a single >>>>> check after filling in those structs whether the option is set and, if so, >>>>> overwrite the two fields. >>>>> >>>>> [1] https://lwn.net/Articles/737947/ >>>> >>>> I don't think that's necessary. As long as the V4 capabilities are a >>>> superset of V1-V3, we should be able to just require all users to >>>> move to V4 (or later) in the next 89 years, and make sure that they >>>> use unsigned seconds if they care about 2038. >>>> >>> >>> Given that V4 wont be around for AF_PACKET -- at least not in the >>> shape of our patches -- Willem's suggestion is probably a good way >>> forward. >> >> That leaves one question: should we do that now, or wait until some >> other reason for a V4 comes up? I don't mind creating another >> patch for this, just want to get a feeling of whether the API clutter >> is worth it when we have a way out that works until y2106 (at >> which point we run into other problems as well). > > I don't expect that we'll have another packet version independent > from the work that Björn is doing. The choice to implement using > a new packet family is given by the complexity of the existing code, > especially the various locking mechanisms. Ok. > From that point of view, and if we want to offer a Y2106 proof > AF_PACKET independent from the above, no reason to wait. Agreed. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
