IB/rdmavt: Free kernel completion queue when done

When a kernel ULP requests the rdmavt to create a completion queue, it
allocated the queue and set cq->kqueue to point to it. However, when the
completion queue is destroyed, cq->queue is freed instead, leading to a
memory leak:

https://lore.kernel.org/r/215235485.15264050.1583334487658.JavaMail.zimbra@redhat.com

 unreferenced object 0xffffc90006639000 (size 12288):
 comm "kworker/u128:0", pid 8, jiffies 4295777598 (age 589.085s)
    hex dump (first 32 bytes):
      4d 00 00 00 4d 00 00 00 00 c0 08 ac 8b 88 ff ff  M...M...........
      00 00 00 00 80 00 00 00 00 00 00 00 10 00 00 00  ................
    backtrace:
      [<0000000035a3d625>] __vmalloc_node_range+0x361/0x720
      [<000000002942ce4f>] __vmalloc_node.constprop.30+0x63/0xb0
      [<00000000f228f784>] rvt_create_cq+0x98a/0xd80 [rdmavt]
      [<00000000b84aec66>] __ib_alloc_cq_user+0x281/0x1260 [ib_core]
      [<00000000ef3764be>] nvme_rdma_cm_handler+0xdb7/0x1b80 [nvme_rdma]
      [<00000000936b401c>] cma_cm_event_handler+0xb7/0x550 [rdma_cm]
      [<00000000d9c40b7b>] addr_handler+0x195/0x310 [rdma_cm]
      [<00000000c7398a03>] process_one_req+0xdd/0x600 [ib_core]
      [<000000004d29675b>] process_one_work+0x920/0x1740
      [<00000000efedcdb5>] worker_thread+0x87/0xb40
      [<000000005688b340>] kthread+0x327/0x3f0
      [<0000000043a168d6>] ret_from_fork+0x3a/0x50

This patch fixes the issue by freeing cq->kqueue instead.

Fixes: 239b0e52 ("IB/hfi1: Move rvt_cq_wc struct into uapi directory")
Link: https://lore.kernel.org/r/20200313123957.14343.43879.stgit@awfm-01.aw.intel.com
Cc: <stable@vger.kernel.org> # 5.4.x
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/sw/rdmavt/cq.c

@@ -327,7 +327,7 @@ void rvt_destroy_cq(struct ib_cq *ibcq, struct ib_udata *udata)
 	if (cq->ip)
 		kref_put(&cq->ip->ref, rvt_release_mmap_info);
 	else
-		vfree(cq->queue);
+		vfree(cq->kqueue);
 }
 
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