RDMA/hns: Use refcount_t instead of atomic_t for QP reference counting

The refcount_t API will WARN on underflow and overflow of a reference
counter, and avoid use-after-free risks.

Link: https://lore.kernel.org/r/1622194663-2383-11-git-send-email-liweihang@huawei.com
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/hns/hns_roce_device.h

@@ -639,7 +639,7 @@ struct hns_roce_qp {
 
 	u32			xrcdn;
 
-	atomic_t		refcount;
+	refcount_t		refcount;
 	struct completion	free;
 
 	struct hns_roce_sge	sge;

drivers/infiniband/hw/hns/hns_roce_qp.c

@@ -65,7 +65,7 @@ static void flush_work_handle(struct work_struct *work)
 	 * make sure we signal QP destroy leg that flush QP was completed
 	 * so that it can safely proceed ahead now and destroy QP
 	 */
-	if (atomic_dec_and_test(&hr_qp->refcount))
+	if (refcount_dec_and_test(&hr_qp->refcount))
 		complete(&hr_qp->free);
 }
 
@@ -75,7 +75,7 @@ void init_flush_work(struct hns_roce_dev *hr_dev, struct hns_roce_qp *hr_qp)
 
 	flush_work->hr_dev = hr_dev;
 	INIT_WORK(&flush_work->work, flush_work_handle);
-	atomic_inc(&hr_qp->refcount);
+	refcount_inc(&hr_qp->refcount);
 	queue_work(hr_dev->irq_workq, &flush_work->work);
 }
 
@@ -87,7 +87,7 @@ void hns_roce_qp_event(struct hns_roce_dev *hr_dev, u32 qpn, int event_type)
 	xa_lock(&hr_dev->qp_table_xa);
 	qp = __hns_roce_qp_lookup(hr_dev, qpn);
 	if (qp)
-		atomic_inc(&qp->refcount);
+		refcount_inc(&qp->refcount);
 	xa_unlock(&hr_dev->qp_table_xa);
 
 	if (!qp) {
@@ -108,7 +108,7 @@ void hns_roce_qp_event(struct hns_roce_dev *hr_dev, u32 qpn, int event_type)
 
 	qp->event(qp, (enum hns_roce_event)event_type);
 
-	if (atomic_dec_and_test(&qp->refcount))
+	if (refcount_dec_and_test(&qp->refcount))
 		complete(&qp->free);
 }
 
@@ -1076,7 +1076,7 @@ static int hns_roce_create_qp_common(struct hns_roce_dev *hr_dev,
 
 	hr_qp->ibqp.qp_num = hr_qp->qpn;
 	hr_qp->event = hns_roce_ib_qp_event;
-	atomic_set(&hr_qp->refcount, 1);
+	refcount_set(&hr_qp->refcount, 1);
 	init_completion(&hr_qp->free);
 
 	return 0;
@@ -1099,7 +1099,7 @@ static int hns_roce_create_qp_common(struct hns_roce_dev *hr_dev,
 void hns_roce_qp_destroy(struct hns_roce_dev *hr_dev, struct hns_roce_qp *hr_qp,
 			 struct ib_udata *udata)
 {
-	if (atomic_dec_and_test(&hr_qp->refcount))
+	if (refcount_dec_and_test(&hr_qp->refcount))
 		complete(&hr_qp->free);
 	wait_for_completion(&hr_qp->free);