RDMA/hns: Use refcount_t instead of atomic_t for CQ 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/1622194663-2383-9-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_cq.c

@@ -154,7 +154,7 @@ static int alloc_cqc(struct hns_roce_dev *hr_dev, struct hns_roce_cq *hr_cq)
 	hr_cq->cons_index = 0;
 	hr_cq->arm_sn = 1;
 
-	atomic_set(&hr_cq->refcount, 1);
+	refcount_set(&hr_cq->refcount, 1);
 	init_completion(&hr_cq->free);
 
 	return 0;
@@ -188,7 +188,7 @@ static void free_cqc(struct hns_roce_dev *hr_dev, struct hns_roce_cq *hr_cq)
 	synchronize_irq(hr_dev->eq_table.eq[hr_cq->vector].irq);
 
 	/* wait for all interrupt processed */
-	if (atomic_dec_and_test(&hr_cq->refcount))
+	if (refcount_dec_and_test(&hr_cq->refcount))
 		complete(&hr_cq->free);
 	wait_for_completion(&hr_cq->free);
 
@@ -480,7 +480,7 @@ void hns_roce_cq_event(struct hns_roce_dev *hr_dev, u32 cqn, int event_type)
 		return;
 	}
 
-	atomic_inc(&hr_cq->refcount);
+	refcount_inc(&hr_cq->refcount);
 
 	ibcq = &hr_cq->ib_cq;
 	if (ibcq->event_handler) {
@@ -490,7 +490,7 @@ void hns_roce_cq_event(struct hns_roce_dev *hr_dev, u32 cqn, int event_type)
 		ibcq->event_handler(&event, ibcq->cq_context);
 	}
 
-	if (atomic_dec_and_test(&hr_cq->refcount))
+	if (refcount_dec_and_test(&hr_cq->refcount))
 		complete(&hr_cq->free);
 }
 

drivers/infiniband/hw/hns/hns_roce_device.h

@@ -444,7 +444,7 @@ struct hns_roce_cq {
 	int				cqe_size;
 	unsigned long			cqn;
 	u32				vector;
-	atomic_t			refcount;
+	refcount_t			refcount;
 	struct completion		free;
 	struct list_head		sq_list; /* all qps on this send cq */
 	struct list_head		rq_list; /* all qps on this recv cq */