Re: [PATCH v2 for-next 3/6] RDMA/rtrs: Fix warning when use poll mode

[Leon Romanovsky <leon@kernel.org>]

On Fri, Aug 06, 2021 at 01:21:09PM +0200, Md Haris Iqbal wrote:
> From: Jack Wang <jinpu.wang@ionos.com>
> 
> when test with poll mode, it will fail and lead to warning below:
> echo "sessname=bla path=gid:fe80::2:c903:4e:d0b3@gid:fe80::2:c903:8:ca17
> device_path=/dev/nullb2 nr_poll_queues=-1" |
> sudo tee /sys/devices/virtual/rnbd-client/ctl/map_device
> 
> rnbd_client L597: Mapping device /dev/nullb2 on session bla,
> (access_mode: rw, nr_poll_queues: 8)
> WARNING: CPU: 3 PID: 9886 at drivers/infiniband/core/cq.c:447 ib_cq_pool_get+0x26f/0x2a0 [ib_core]
> 
> The problem is, when poll_queues are used, there will be more connections than
> number of cpus; and those extra connections will have ib poll context set to
> IB_POLL_DIRECT, which is not allowed to be used for shared CQs.
> 
> So, in case those extra connections when poll queues are used, use
> ib_alloc_cq/ib_free_cq.
> 
> Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
> Reviewed-by: Gioh Kim <gi-oh.kim@ionos.com>
> Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
> ---
>  drivers/infiniband/ulp/rtrs/rtrs-srv.c |  1 +
>  drivers/infiniband/ulp/rtrs/rtrs.c     | 17 ++++++++++++++---
>  2 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/infiniband/ulp/rtrs/rtrs-srv.c b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
> index cd9a4ccf4c28..47775987f91a 100644
> --- a/drivers/infiniband/ulp/rtrs/rtrs-srv.c
> +++ b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
> @@ -1768,6 +1768,7 @@ static struct rtrs_srv_sess *__alloc_sess(struct rtrs_srv *srv,
>  	strscpy(sess->s.sessname, str, sizeof(sess->s.sessname));
>  
>  	sess->s.con_num = con_num;
> +	sess->s.irq_con_num = con_num;
>  	sess->s.recon_cnt = recon_cnt;
>  	uuid_copy(&sess->s.uuid, uuid);
>  	spin_lock_init(&sess->state_lock);
> diff --git a/drivers/infiniband/ulp/rtrs/rtrs.c b/drivers/infiniband/ulp/rtrs/rtrs.c
> index ca542e477d38..9bc323490ce3 100644
> --- a/drivers/infiniband/ulp/rtrs/rtrs.c
> +++ b/drivers/infiniband/ulp/rtrs/rtrs.c
> @@ -228,7 +228,12 @@ static int create_cq(struct rtrs_con *con, int cq_vector, int nr_cqe,
>  	struct rdma_cm_id *cm_id = con->cm_id;
>  	struct ib_cq *cq;
>  
> -	cq = ib_cq_pool_get(cm_id->device, nr_cqe, cq_vector, poll_ctx);
> +	if (con->cid >= con->sess->irq_con_num)
> +		cq = ib_alloc_cq(cm_id->device, con, nr_cqe, cq_vector,
> +				 poll_ctx);
> +	else
> +		cq = ib_cq_pool_get(cm_id->device, nr_cqe, cq_vector, poll_ctx);

I see same "if (con->c.cid >= sess->s.irq_con_num)" checks when calling
to rtrs_cq_qp_create() that will take poll_ctx and convey it to create_cq().

Please take a look on nvme_rdma_create_cq() which does the same without
passing poll_ctx.

Thanks