On Mon, Sep 3, 2018 at 10:12 AM Vlad Buslov <vla...@mellanox.com> wrote: > > > On Mon 03 Sep 2018 at 17:03, Cong Wang <xiyou.wangc...@gmail.com> wrote: > > On Mon, Sep 3, 2018 at 12:10 AM Vlad Buslov <vla...@mellanox.com> wrote: > >> > >> Recent refactoring of add_metainfo() caused use_all_metadata() to add > >> metainfo to ife action metalist without taking reference to module. This > >> causes warning in module_put called from ife action cleanup function. > >> > >> Implement add_metainfo_and_get_ops() function that returns with reference > >> to module taken if metainfo was added successfully, and call it from > >> use_all_metadata(), instead of calling __add_metainfo() directly. > > > > Good catch! > > > > I thought every entry in ifeoplist must hold a refcnt to its module, looks > > like I was wrong. > > > > > >> read_lock(&ife_mod_lock); > >> list_for_each_entry(o, &ifeoplist, list) { > >> - rc = __add_metainfo(o, ife, o->metaid, NULL, 0, true, > >> exists); > >> + rc = add_metainfo_and_get_ops(o, ife, o->metaid, NULL, 0, > >> true, > >> + exists); > >> if (rc == 0) > >> installed += 1; > > > > I am afraid you have to rollback on failure inside this loop, that is, > > releasing all previous module refcnt properly on error. > > Do I? This function looks like it is explicitly designed to succeed if > at least one metainfo was successfully added. And this is how it was > originally implemented before deadlock fix refactoring.
Hmm, well, it is taken care by tcf_idr_release() via _tcf_ife_cleanup()... So, your patch should be fine.