[Cake] lockup with multiple cake instances on 3.16.7

[Toke Høiland-Jørgensen]

Pete Heist <pete at heistp.net> writes:

> I’m seeing a lockup with cake on 3.16.7 with 64-bit Intel when adding
> more than 4 cake instances. I’m using cake and tc-adv from head. Does
> anyone have an idea what this could be?

Looks like it's a compatibility issue with old kernels. Could you please
check if the latest commit in the github repo fixes this? :)

The explanation, copied from that commit:

> The qdisc stats dumping was changed in 4.8 (by commit
> edb09eb17ed89eaa82a52dd306beac93e292b485) to be lockless and moving the
> responsibility for taking the qdisc root lock into the qdisc itself. Cake
> inherited this from FQ-CoDel, but it leads to deadlocks on old kernels
> where the core stats dumping code still takes the root qdisc lock.


-Toke