On Friday, October 30, 2015 at 03:53:31 PM, Oliver Hartkopp wrote: > On 10/30/2015 03:24 PM, Marek Vasut wrote: > > On Friday, October 30, 2015 at 03:17:44 PM, Marc Kleine-Budde wrote: > >> On 10/30/2015 03:01 PM, Marek Vasut wrote: > >>> Are you absolutelly positive this doesn't break kernel ABI please ? > >>> > >>> I am a little worried there, since the size of can_clock and > >>> can_ctrlmode structures differ. > >> > >> struct can_clock is a u32, see [1] > >> struct can_ctrlmode is 2 x u32. > >> > >> in libsocketcan[2] it's accessed like this: > >>> memcpy(res, > >>> > >>> RTA_DATA(can_attr[IFLA_CAN_CLOCK]), > >>> sizeof(struct can_clock)); > >> > >> I think it should be ok. > > > > In that case, yes, it's good. Hopefully, noone wrote his own thing. > > Fortunately ip from iproute2 does it similary: > > https://git.kernel.org/cgit/linux/kernel/git/shemminger/iproute2.git/tree/i > p/iplink_can.c#n338 > > > if (tb[IFLA_CAN_CLOCK]) { > struct can_clock *clock = RTA_DATA(tb[IFLA_CAN_CLOCK]); > > fprintf(f, "\n clock %d", clock->freq); > } > > As the clock is a read-only value kernel->userspace and nla_put creates its > own small ID/length information each time we are REALLY LUCKY that this fix > doesn't break the ABI in this case. > > When can_clock would have been greater then can_ctrlmode we really had a > problem ... > > Thanks for caching this!
Yeah, I already had one leg in my asbestos trousers all right. Thanks for double-checking this! Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
