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

From: Leon Romanovsky
Date: Mon Apr 10 2023 - 08:08:46 EST

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+
> |
> 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 |
> }
>
> Simply, Here we can avoid this warning by introducing conn own flag to
> track if its cleanup should drop the PD.
>
> -----------------------------------------------
> rnbd_client L597: Mapping device /dev/nvme0n1 on session client, (access_mode: rw, nr_poll_queues: 0)
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 26407 at drivers/infiniband/sw/rxe/rxe_pool.c:256 __rxe_cleanup+0x13a/0x170 [rdma_rxe]
> Modules linked in: rpcrdma rdma_ucm ib_iser rnbd_client libiscsi rtrs_client scsi_transport_iscsi rtrs_core rdma_cm iw_cm ib_cm crc32_generic rdma_rxe udp_tunnel ib_uverbs ib_core kmem device_dax nd_pmem dax_pmem nd_
> vme crc32c_intel fuse nvme_core nfit libnvdimm dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua dm_mirror dm_region_hash dm_log dm_mod
> CPU: 0 PID: 26407 Comm: rnbd-client.sh Kdump: loaded Not tainted 6.2.0-rc6-roce-flush+ #53
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
> RIP: 0010:__rxe_cleanup+0x13a/0x170 [rdma_rxe]
> Code: 45 84 e4 0f 84 5a ff ff ff 48 89 ef e8 5f 18 71 f9 84 c0 75 90 be c8 00 00 00 48 89 ef e8 be 89 1f fa 85 c0 0f 85 7b ff ff ff <0f> 0b 41 bc ea ff ff ff e9 71 ff ff ff e8 84 7f 1f fa e9 d0 fe ff
> RSP: 0018:ffffb09880b6f5f0 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: ffff99401f15d6a8 RCX: 0000000000000000
> RDX: 0000000000000001 RSI: ffffffffbac8234b RDI: 00000000ffffffff
> RBP: ffff99401f15d6d0 R08: 0000000000000001 R09: 0000000000000001
> R10: 0000000000002d82 R11: 0000000000000000 R12: 0000000000000001
> R13: ffff994101eff208 R14: ffffb09880b6f6a0 R15: 00000000fffffe00
> FS: 00007fe113904740(0000) GS:ffff99413bc00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ff6cde656c8 CR3: 000000001f108004 CR4: 00000000001706f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> rxe_dealloc_pd+0x16/0x20 [rdma_rxe]
> ib_dealloc_pd_user+0x4b/0x80 [ib_core]
> rtrs_ib_dev_put+0x79/0xd0 [rtrs_core]
> destroy_con_cq_qp+0x8a/0xa0 [rtrs_client]
> init_path+0x1e7/0x9a0 [rtrs_client]
> ? __pfx_autoremove_wake_function+0x10/0x10
> ? lock_is_held_type+0xd7/0x130
> ? rcu_read_lock_sched_held+0x43/0x80
> ? pcpu_alloc+0x3dd/0x7d0
> ? rtrs_clt_init_stats+0x18/0x40 [rtrs_client]
> rtrs_clt_open+0x24f/0x5a0 [rtrs_client]
> ? __pfx_rnbd_clt_link_ev+0x10/0x10 [rnbd_client]
> rnbd_clt_map_device+0x6a5/0xe10 [rnbd_client]
>
> Signed-off-by: Li Zhijian <lizhijian@xxxxxxxxxxx>
> ---
> drivers/infiniband/ulp/rtrs/rtrs-clt.c | 4 ++++
> drivers/infiniband/ulp/rtrs/rtrs-clt.h | 1 +
> 2 files changed, 5 insertions(+)
>
> diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.c b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> index c2065fc33a56..4c8f42e46e2f 100644
> --- a/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> +++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.c
> @@ -1664,6 +1664,7 @@ static int create_con_cq_qp(struct rtrs_clt_con *con)
> return -ENOMEM;
> }
> clt_path->s.dev_ref = 1;
> + con->has_dev = true;
> query_fast_reg_mode(clt_path);
> wr_limit = clt_path->s.dev->ib_dev->attrs.max_qp_wr;
> /*
> @@ -1690,6 +1691,7 @@ static int create_con_cq_qp(struct rtrs_clt_con *con)
> wr_limit = clt_path->s.dev->ib_dev->attrs.max_qp_wr;
> /* Shared between connections */
> clt_path->s.dev_ref++;

Without looking in the code, I would expect dev_ref from the line above
to perform PD protection.

> + con->has_dev = true;
> max_send_wr = min_t(int, wr_limit,
> /* QD * (REQ + RSP + FR REGS or INVS) + drain */
> clt_path->queue_depth * 3 + 1);
> @@ -1742,6 +1744,8 @@ static void destroy_con_cq_qp(struct rtrs_clt_con *con)
> con->rsp_ius = NULL;
> con->queue_num = 0;
> }
> + if (!con->has_dev)
> + return;
> if (clt_path->s.dev_ref && !--clt_path->s.dev_ref) {
> rtrs_ib_dev_put(clt_path->s.dev);
> clt_path->s.dev = NULL;
> diff --git a/drivers/infiniband/ulp/rtrs/rtrs-clt.h b/drivers/infiniband/ulp/rtrs/rtrs-clt.h
> index f848c0392d98..970b75633594 100644
> --- a/drivers/infiniband/ulp/rtrs/rtrs-clt.h
> +++ b/drivers/infiniband/ulp/rtrs/rtrs-clt.h
> @@ -75,6 +75,7 @@ struct rtrs_clt_con {
> unsigned int cpu;
> struct mutex con_mutex;
> int cm_err;
> + bool has_dev;
> };
>
> /**
> --
> 2.29.2
>