RDMA/hns: Fix flush cqe error when racing with destroy qp

QP needs to be modified to IB_QPS_ERROR to trigger HW flush cqe. But
when this process races with destroy qp, the destroy-qp process may
modify the QP to IB_QPS_RESET first. In this case flush cqe will fail
since it is invalid to modify qp from IB_QPS_RESET to IB_QPS_ERROR.

Add lock and bit flag to make sure pending flush cqe work is completed
first and no more new works will be added.

Fixes: ffd541d ("RDMA/hns: Add the workqueue framework for flush cqe handler")
Signed-off-by: wenglianfa <wenglianfa@huawei.com>
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
Link: https://patch.msgid.link/20241024124000.2931869-3-huangjunxian6@hisilicon.com
Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

Author: wenglianfa

drivers/infiniband/hw/hns/hns_roce_device.h

@@ -593,6 +593,7 @@ struct hns_roce_dev;
 
 enum {
 	HNS_ROCE_FLUSH_FLAG = 0,
+	HNS_ROCE_STOP_FLUSH_FLAG = 1,
 };
 
 struct hns_roce_work {
@@ -656,6 +657,7 @@ struct hns_roce_qp {
 	enum hns_roce_cong_type	cong_type;
 	u8			tc_mode;
 	u8			priority;
+	spinlock_t flush_lock;
 };
 
 struct hns_roce_ib_iboe {

drivers/infiniband/hw/hns/hns_roce_hw_v2.c

@@ -5598,8 +5598,15 @@ int hns_roce_v2_destroy_qp(struct ib_qp *ibqp, struct ib_udata *udata)
 {
 	struct hns_roce_dev *hr_dev = to_hr_dev(ibqp->device);
 	struct hns_roce_qp *hr_qp = to_hr_qp(ibqp);
+	unsigned long flags;
 	int ret;
 
+	/* Make sure flush_cqe() is completed */
+	spin_lock_irqsave(&hr_qp->flush_lock, flags);
+	set_bit(HNS_ROCE_STOP_FLUSH_FLAG, &hr_qp->flush_flag);
+	spin_unlock_irqrestore(&hr_qp->flush_lock, flags);
+	flush_work(&hr_qp->flush_work.work);
+
 	ret = hns_roce_v2_destroy_qp_common(hr_dev, hr_qp, udata);
 	if (ret)
 		ibdev_err(&hr_dev->ib_dev,

drivers/infiniband/hw/hns/hns_roce_qp.c

@@ -90,11 +90,18 @@ static void flush_work_handle(struct work_struct *work)
 void init_flush_work(struct hns_roce_dev *hr_dev, struct hns_roce_qp *hr_qp)
 {
 	struct hns_roce_work *flush_work = &hr_qp->flush_work;
+	unsigned long flags;
+
+	spin_lock_irqsave(&hr_qp->flush_lock, flags);
+	/* Exit directly after destroy_qp() */
+	if (test_bit(HNS_ROCE_STOP_FLUSH_FLAG, &hr_qp->flush_flag)) {
+		spin_unlock_irqrestore(&hr_qp->flush_lock, flags);
+		return;
+	}
 
-	flush_work->hr_dev = hr_dev;
-	INIT_WORK(&flush_work->work, flush_work_handle);
 	refcount_inc(&hr_qp->refcount);
 	queue_work(hr_dev->irq_workq, &flush_work->work);
+	spin_unlock_irqrestore(&hr_qp->flush_lock, flags);
 }
 
 void flush_cqe(struct hns_roce_dev *dev, struct hns_roce_qp *qp)
@@ -1140,6 +1147,7 @@ static int hns_roce_create_qp_common(struct hns_roce_dev *hr_dev,
 				     struct ib_udata *udata,
 				     struct hns_roce_qp *hr_qp)
 {
+	struct hns_roce_work *flush_work = &hr_qp->flush_work;
 	struct hns_roce_ib_create_qp_resp resp = {};
 	struct ib_device *ibdev = &hr_dev->ib_dev;
 	struct hns_roce_ib_create_qp ucmd = {};
@@ -1148,9 +1156,12 @@ static int hns_roce_create_qp_common(struct hns_roce_dev *hr_dev,
 	mutex_init(&hr_qp->mutex);
 	spin_lock_init(&hr_qp->sq.lock);
 	spin_lock_init(&hr_qp->rq.lock);
+	spin_lock_init(&hr_qp->flush_lock);
 
 	hr_qp->state = IB_QPS_RESET;
 	hr_qp->flush_flag = 0;
+	flush_work->hr_dev = hr_dev;
+	INIT_WORK(&flush_work->work, flush_work_handle);
 
 	if (init_attr->create_flags)
 		return -EOPNOTSUPP;