On Thu, Apr 13, 2023 at 08:12:15AM +0000, Zhijian Li (Fujitsu) wrote:
>
>
> On 13/04/2023 15:35, Guoqing Jiang wrote:
> > Hi,
> >
> > I take a closer look today.
> >
> > On 4/12/23 09:15, Zhijian Li (Fujitsu) wrote:
> >>
> >> On 11/04/2023 20:26, Leon Romanovsky wrote:
> >>> On Tue, Apr 11, 2023 at 02:43:46AM +0000, Zhijian Li (Fujitsu) wrote:
> >>>>
> >>>> On 10/04/2023 21:10, Guoqing Jiang wrote:
> >>>>>
> >>>>> On 4/10/23 20:08, Leon Romanovsky wrote:
> >>>>>> On Mon, Apr 10, 2023 at 06:43:03AM +0000, Li Zhijian wrote:
> >>>>>>> The warning occurs when destroying PD whose reference count is not zero.
> >>>>>>>
> >>>>>>> Precodition: clt_path->s.con_num is 2.
> >>>>>>> So 2 cm connection will be created as below:
> >>>>>>> CPU0 CPU1
> >>>>>>> init_conns { |
> >>>>>>> create_cm() // a. con[0] created |
> >>>>>>> | a'. rtrs_clt_rdma_cm_handler() {
> >>>>>>> | rtrs_rdma_addr_resolved()
> >>>>>>> | create_con_cq_qp(con); << con[0]
> >>>>>>> | }
> >>>>>>> | in this moment, refcnt of PD was increased to 2+
> >
> > What do you mean "refcnt of PD"? usecnt in struct ib_pd or dev_ref.
>
> I mean usecnt in struct ib_pd
>
>
>
> >
> >>>>>>> |
> >>>>>>> create_cm() // b. cid = 1, failed |
> >>>>>>> destroy_con_cq_qp() |
> >>>>>>> rtrs_ib_dev_put() |
> >>>>>>> dev_free() |
> >>>>>>> ib_dealloc_pd(dev->ib_pd) << PD |
> >>>>>>> is destroyed, but refcnt is |
> >>>>>>> still greater than 0 |
> >
> > Assuming you mean "pd->usecnt". We only allocate pd in con[0] by rtrs_ib_dev_find_or_add,
> > if con[1] failed to create cm, then alloc_path_reqs -> ib_alloc_mr -> atomic_inc(&pd->usecnt)
> > can't be triggered. Is there other places could increase the refcnt?
>
>
> Yes, when create a qp, it will also associate to this PD, that also mean refcnt of PD will be increased.
>
> When con[0](create_con_cq_qp) succeeded, refcnt of PD will be 2. and then when con[1] failed, since
> QP didn't create, refcnt of PD is still 2. con[1]'s cleanup will destroy the PD(ib_dealloc_pd) since dev_ref = 1, after that its
> refcnt is still 1.
Why is refcnt 1 in con[1] destruction phase? It seems to me like a bug.
Thanks
