by Jinpu Wang

[permalink] [raw]

Subject: Re: [PATCH for-next 2/3] RDMA/rtrs: Fix rxe_dealloc_pd warning

On Fri, Apr 21, 2023 at 3:38 AM Zhijian Li (Fujitsu)
<[email protected]> wrote:
>
> Jinpu
>
> I updated the changes as below, and tested for thousand rounds.
>
> From d441c0e2496c1795b5af2b6b8ae4672203d6af3c Mon Sep 17 00:00:00 2001
> From: Li Zhijian <[email protected]>
> Date: Thu, 20 Apr 2023 17:28:28 +0800
> Subject: [PATCH] RDMA/rtrs: Fix rxe_dealloc_pd warning
>
> In current design:
> 1. PD and clt_path->s.dev are shared among connections.
> 2. every con[n]'s cleanup phase will call destroy_con_cq_qp()
> 3. clt_path->s.dev will be always decreased in destroy_con_cq_qp(), and
> when clt_path->s.dev become zero, it will destroy PD.
> 4. when con[1] failed to create, con[1] will not take clt_path->s.dev,
> but it try to decreased clt_path->s.dev
>
> So, in case create_cm(con[0]) succeeds but create_cm(con[1])
> fails, destroy_con_cq_qp(con[1]) will be called first which will destory
> the PD while this PD is still taken by con[0].
>
> Here, we refactor the error path of create_cm() and init_conns(), so that
> we do the cleanup in the order they are created.
>
> Signed-off-by: Li Zhijian <[email protected]>
> ---
> drivers/infiniband/ulp/rtrs/rtrs-clt.c | 47 +++++++++++---------------
> 1 file changed, 19 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> index 80abf45a197a..5faf0ecb726b 100644
> --- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> +++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> @@ -2040,6 +2040,7 @@ static int rtrs_clt_rdma_cm_handler(struct rdma_cm_id *cm_id,
> return 0;
> }
>
> +/* The caller should the do the cleanup in case of error */
> static int create_cm(struct rtrs_clt_con *con)
> {
> struct rtrs_path *s = con->c.path;
> @@ -2062,14 +2063,14 @@ static int create_cm(struct rtrs_clt_con *con)
> err = rdma_set_reuseaddr(cm_id, 1);
> if (err != 0) {
> rtrs_err(s, "Set address reuse failed, err: %d\n", err);
> - goto destroy_cm;
> + return err;
> }
> err = rdma_resolve_addr(cm_id, (struct sockaddr *)&clt_path->s.src_addr,
> (struct sockaddr *)&clt_path->s.dst_addr,
> RTRS_CONNECT_TIMEOUT_MS);
> if (err) {
> rtrs_err(s, "Failed to resolve address, err: %d\n", err);
> - goto destroy_cm;
> + return err;
> }
> /*
> * Combine connection status and session events. This is needed
> @@ -2084,29 +2085,17 @@ static int create_cm(struct rtrs_clt_con *con)
> if (err == 0)
> err = -ETIMEDOUT;
> /* Timedout or interrupted */
> - goto errr;
> + return err;
> }
> if (con->cm_err < 0) {
> - err = con->cm_err;
> - goto errr;
> + return con->cm_err;
> }
The bracket can be removed too
> if (READ_ONCE(clt_path->state) != RTRS_CLT_CONNECTING) {
> /* Device removal */
> - err = -ECONNABORTED;
> - goto errr;
> + return -ECONNABORTED;
> }
same here.
>
> return 0;
> -
> -errr:
> - stop_cm(con);
> - mutex_lock(&con->con_mutex);
> - destroy_con_cq_qp(con);
> - mutex_unlock(&con->con_mutex);
> -destroy_cm:
> - destroy_cm(con);
> -
> - return err;
> }
>
> static void rtrs_clt_path_up(struct rtrs_clt_path *clt_path)
> @@ -2334,7 +2323,7 @@ static void rtrs_clt_close_work(struct work_struct *work)
> static int init_conns(struct rtrs_clt_path *clt_path)
> {
> unsigned int cid;
> - int err;
> + int err, i;
>
> /*
> * On every new session connections increase reconnect counter
> @@ -2350,10 +2339,8 @@ static int init_conns(struct rtrs_clt_path *clt_path)
> goto destroy;
>
> err = create_cm(to_clt_con(clt_path->s.con[cid]));
> - if (err) {
> - destroy_con(to_clt_con(clt_path->s.con[cid]));
> + if (err)
> goto destroy;
> - }
> }
> err = alloc_path_reqs(clt_path);
> if (err)
> @@ -2364,15 +2351,19 @@ static int init_conns(struct rtrs_clt_path *clt_path)
> return 0;
>
> destroy:
> - while (cid--) {
> + /* Make sure we do the cleanup in the order they are created */
> + for (i = 0; i <= cid; i++) {
> struct rtrs_clt_con *con = to_clt_con(clt_path->s.con[cid]);
Yes, this line has to be adapted.
struct rtrs_clt_con *con = to_clt_con(clt_path->s.con[i]);
>
> - stop_cm(con);
> -
> - mutex_lock(&con->con_mutex);
> - destroy_con_cq_qp(con);
> - mutex_unlock(&con->con_mutex);
> - destroy_cm(con);
> + if (!con)
> + break;
> + if (con->c.cm_id) {
> + stop_cm(con);
> + mutex_lock(&con->con_mutex);
> + destroy_con_cq_qp(con);
> + mutex_unlock(&con->con_mutex);
> + destroy_cm(con);
> + }
> destroy_con(con);
> }
> /*
> --
> 2.29.2
>
This version looks fine. I will run some tests.

Thx!
>
>
> On 20/04/2023 10:00, Li Zhijian wrote:
> > On 19/04/2023 21:20, Jinpu Wang wrote:
> >> On Wed, Apr 19, 2023 at 11:53 AM Zhijian Li (Fujitsu)
> >> <[email protected]> wrote:
> >>>
> >>> Leon, Guoqing
> >>>
> >>>
> >>> On 18/04/2023 15:57, Leon Romanovsky wrote:
> >>>>>>> Currently, without this patch:
> >>>>>>> 1. PD and clt_path->s.dev are shared among connections.
> >>>>>>> 2. every con[n]'s cleanup phase will call destroy_con_cq_qp()
> >>>>>>> 3. clt_path->s.dev will be always decreased in destroy_con_cq_qp(), and when
> >>>>>>> clt_path->s.dev become zero, it will destroy PD.
> >>>>>>> 4. when con[1] failed to create, con[1] will not take clt_path->s.dev, but it try to decreased clt_path->s.dev <<< it's wrong to do that.
> >>>>>> So please fix it by making sure that failure to create con[1] will
> >>>>>> release resources which were allocated. If con[1] didn't increase
> >>>>>> s.dev_ref, it shouldn't decrease it either.
> >>>>> You are right, the current patch did exactly that.
> >>>>> It introduced a con owning flag 'has_dev' to indicate whether this con has taken s.dev.
> >>>>> so that its cleanup phase will only decrease its s.dev properly.
> >>>> The has_dev is a workaround and not a solution. In proper error unwind
> >>>> sequence, you won't need extra flag.