On Tue, Dec 11, 2018 at 2:19 AM Vlad Buslov <vla...@mellanox.com> wrote: > > As a part of the effort to remove dependency on rtnl lock, cls API is being > converted to use fine-grained locking mechanisms instead of global rtnl > lock. However, chain_head_change callback for ingress Qdisc is a sleeping > function and cannot be executed while holding a spinlock.
Why does it have to be a spinlock not a mutex? I've read your cover letter and this changelog, I don't find any answer. > > Extend cls API with new workqueue intended to be used for tcf_proto > lifetime management. Modify tcf_proto_destroy() to deallocate proto > asynchronously on workqueue in order to ensure that all chain_head_change > callbacks involving the proto complete before it is freed. Convert > mini_qdisc_pair_swap(), that is used as a chain_head_change callback for > ingress and clsact Qdiscs, to use a workqueue. Move Qdisc deallocation to > tc_proto_wq ordered workqueue that is used to destroy tcf proto instances. > This is necessary to ensure that Qdisc is destroyed after all instances of > chain/proto that it contains in order to prevent use-after-free error in > tc_chain_notify_delete(). Please avoid async unless you have to, there are almost always bugs when playing with deferred workqueue or any other callbacks. Thanks.
