RDMA/rtrs: Add missing deinit() call

A warning is triggered when repeatedly connecting and disconnecting the
rnbd:
 list_add corruption. prev->next should be next (ffff88800b13e480), but was ffff88801ecd1338. (prev=ffff88801ecd1340).
 WARNING: CPU: 1 PID: 36562 at lib/list_debug.c:32 __list_add_valid_or_report+0x7f/0xa0
 Workqueue: ib_cm cm_work_handler [ib_cm]
 RIP: 0010:__list_add_valid_or_report+0x7f/0xa0
  ? __list_add_valid_or_report+0x7f/0xa0
  ib_register_event_handler+0x65/0x93 [ib_core]
  rtrs_srv_ib_dev_init+0x29/0x30 [rtrs_server]
  rtrs_ib_dev_find_or_add+0x124/0x1d0 [rtrs_core]
  __alloc_path+0x46c/0x680 [rtrs_server]
  ? rtrs_rdma_connect+0xa6/0x2d0 [rtrs_server]
  ? rcu_is_watching+0xd/0x40
  ? __mutex_lock+0x312/0xcf0
  ? get_or_create_srv+0xad/0x310 [rtrs_server]
  ? rtrs_rdma_connect+0xa6/0x2d0 [rtrs_server]
  rtrs_rdma_connect+0x23c/0x2d0 [rtrs_server]
  ? __lock_release+0x1b1/0x2d0
  cma_cm_event_handler+0x4a/0x1a0 [rdma_cm]
  cma_ib_req_handler+0x3a0/0x7e0 [rdma_cm]
  cm_process_work+0x28/0x1a0 [ib_cm]
  ? _raw_spin_unlock_irq+0x2f/0x50
  cm_req_handler+0x618/0xa60 [ib_cm]
  cm_work_handler+0x71/0x520 [ib_cm]

Commit 667db86 ("RDMA/rtrs: Register ib event handler") introduced a
new element .deinit but never used it at all. Fix it by invoking the
`deinit()` to appropriately unregister the IB event handler.

Cc: Jinpu Wang <jinpu.wang@ionos.com>
Fixes: 667db86 ("RDMA/rtrs: Register ib event handler")
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Link: https://patch.msgid.link/20250106004516.16611-1-lizhijian@fujitsu.com
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

Author: zhijianli88

drivers/infiniband/ulp/rtrs/rtrs.c

@@ -584,6 +584,9 @@ static void dev_free(struct kref *ref)
 	list_del(&dev->entry);
 	mutex_unlock(&pool->mutex);
 
+	if (pool->ops && pool->ops->deinit)
+		pool->ops->deinit(dev);
+
 	ib_dealloc_pd(dev->ib_pd);
 	kfree(dev);
 }