> On 2 Jul 2018, at 18:04, Pete Heist wrote: > > > >> On Jul 2, 2018, at 6:14 PM, Toke Høiland-Jørgensen wrote: >> >> Aha! I think I figured out what is going on: >> >> The gen_stats facility will add an nlattr header at the beginning of the >> qdisc stats, which is the toplevel TLV that contains all stats (and that >> we put our stats inside). It stores a reference to this header, and when >> all the per-qdisc callbacks have finished adding their stats, it goes >> back and fixes up the length of the containing header. >> >> The problem is that on architectures that need padding, the padding TLV >> is added *first*, which means that the nlattr pointer that is stored >> before the callbacks are performed points to the padding TLV and not the >> stats TLV. And so, when the header is fixed up, the result (from the >> parser's perspective) is just a very big padding TLV. >> >> The options TLV is before the stats TLV, so the bug only occurs if the >> options happen to have a length that means the stats will need padding. >> Which is why messing with the number of options "fixes" the bug. >> >> Could you try applying the patch below (to the kernel) and see if that >> resolves the issue, please? > > Awesome Toke! It looks like from Kevin’s email that it works for him, but it didn’t work for me the first time around. This may have to do with how I added the patch as I’m still not that familiar with OpenWRT’s build system (first kernel patch I tried). I wasn’t sure if it should go into generic or platform, for one, so I tried generic…is that right? > > sysadmin@rey:~/src/openwrt/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/linux-4.9.109/patches/generic$ cat 010-gen_stats_fix.patch > --- a/net/core/gen_stats.c > +++ b/net/core/gen_stats.c > @@ -77,8 +77,12 @@ gnet_stats_start_copy_compat(struct sk_b > d->lock = lock; > spin_lock_bh(lock); > } > - if (d->tail) > - return gnet_stats_copy(d, type, NULL, 0, padattr); > + if (d->tail) { > + int ret = gnet_stats_copy(d, type, NULL, 0, padattr); > + if (!ret) > + d->tail = ((struct nlattr *)skb_tail_pointer(skb)) - 1; > + return ret; > + } > > return 0; > } > generic is where it should go, but what I did was: make package/iproute2/clean make package/kmod-sched-cake/clean - both to be *really* sure they get rebuilt, shouldn’t be required but!!! make target/linux/{clean,prepare} (this gets the kernel build tree in a ready to build state with all the openwrt patches) edit build/target_mips34*/linux*/linux*/net/core/genstat.c directly make flash the image - test :-) I assume tha patch has been tried on previously unbroken arch’s and they remain unb0rked ? Cheers, Kevin D-B 012C ACB2 28C6 C53E 9775 9123 B3A2 389B 9DE2 334A