On Thu 13 Sep 2018 at 17:13, Cong Wang <xiyou.wangc...@gmail.com> wrote: > On Wed, Sep 12, 2018 at 1:51 AM Vlad Buslov <vla...@mellanox.com> wrote: >> >> >> On Fri 07 Sep 2018 at 19:12, Cong Wang <xiyou.wangc...@gmail.com> wrote: >> > On Fri, Sep 7, 2018 at 6:52 AM Vlad Buslov <vla...@mellanox.com> wrote: >> >> >> >> Action API was changed to work with actions and action_idr in concurrency >> >> safe manner, however tcf_del_walker() still uses actions without taking a >> >> reference or idrinfo->lock first, and deletes them directly, disregarding >> >> possible concurrent delete. >> >> >> >> Add tc_action_wq workqueue to action API. Implement >> >> tcf_idr_release_unsafe() that assumes external synchronization by caller >> >> and delays blocking action cleanup part to tc_action_wq workqueue. Extend >> >> tcf_action_cleanup() with 'async' argument to indicate that function >> >> should >> >> free action asynchronously. >> > >> > Where exactly is blocking in tcf_action_cleanup()? >> > >> > From your code, it looks like free_tcf(), but from my observation, >> > the only blocking function inside is tcf_action_goto_chain_fini() >> > which calls __tcf_chain_put(). But, __tcf_chain_put() is blocking >> > _ONLY_ when tc_chain_notify() is called, for tc action it is never >> > called. >> > >> > So, what else is blocking? >> >> __tcf_chain_put() calls tc_chain_tmplt_del(), which calls >> ops->tmplt_destroy(). This last function uses hw offload API, which is >> blocking. > > Good to know. > > Can we just make ops->tmplt_destroy() to use workqueue? > Making tc action to workqueue seems overkill, for me.
How about changing tcf_chain_put_by_act() to use tc_filter_wq, instead of directly calling __tcf_chain_put()? IMO it is a better solution because it benefits all classifiers, instead of requiring every classifier with templates support to implement non-blocking ops->tmplt_destroy().
