[PATCH for-rc] RDMA/hns: Use mutex instead of spinlock for ida allocation

[PATCH for-rc] RDMA/hns: Use mutex instead of spinlock for ida allocation

[Weihang Li]

From: Yangyang Li <liyangyang20@huawei.com>

GFP_KERNEL may cause ida_alloc_range() to sleep, but the spinlock covering
this function is not allowed to sleep, so the spinlock needs to be changed
to mutex.

As there is a certain chance of memory allocation failure, GFP_ATOMIC
is not suitable for QP allocation scenarios.

Fixes: 71586dd20010 ("RDMA/hns: Create QP with selected QPN for bank load balance")
Signed-off-by: Yangyang Li <liyangyang20@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
---
 drivers/infiniband/hw/hns/hns_roce_device.h |  2 +-
 drivers/infiniband/hw/hns/hns_roce_qp.c     | 11 ++++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/hw/hns/hns_roce_device.h b/drivers/infiniband/hw/hns/hns_roce_device.h
index 55d5386..ad82532 100644
--- a/drivers/infiniband/hw/hns/hns_roce_device.h
+++ b/drivers/infiniband/hw/hns/hns_roce_device.h
@@ -532,7 +532,7 @@ struct hns_roce_qp_table {
 	struct hns_roce_hem_table	sccc_table;
 	struct mutex			scc_mutex;
 	struct hns_roce_bank bank[HNS_ROCE_QP_BANK_NUM];
-	spinlock_t bank_lock;
+	struct mutex bank_mutex;
 };
 
 struct hns_roce_cq_table {
diff --git a/drivers/infiniband/hw/hns/hns_roce_qp.c b/drivers/infiniband/hw/hns/hns_roce_qp.c
index d8e2fe5..1116371 100644
--- a/drivers/infiniband/hw/hns/hns_roce_qp.c
+++ b/drivers/infiniband/hw/hns/hns_roce_qp.c
@@ -209,7 +209,7 @@ static int alloc_qpn(struct hns_roce_dev *hr_dev, struct hns_roce_qp *hr_qp)
 
 		hr_qp->doorbell_qpn = 1;
 	} else {
-		spin_lock(&qp_table->bank_lock);
+		mutex_lock(&qp_table->bank_mutex);
 		bankid = get_least_load_bankid_for_qp(qp_table->bank);
 
 		ret = alloc_qpn_with_bankid(&qp_table->bank[bankid], bankid,
@@ -217,12 +217,12 @@ static int alloc_qpn(struct hns_roce_dev *hr_dev, struct hns_roce_qp *hr_qp)
 		if (ret) {
 			ibdev_err(&hr_dev->ib_dev,
 				  "failed to alloc QPN, ret = %d\n", ret);
-			spin_unlock(&qp_table->bank_lock);
+			mutex_unlock(&qp_table->bank_mutex);
 			return ret;
 		}
 
 		qp_table->bank[bankid].inuse++;
-		spin_unlock(&qp_table->bank_lock);
+		mutex_unlock(&qp_table->bank_mutex);
 
 		hr_qp->doorbell_qpn = (u32)num;
 	}
@@ -408,9 +408,9 @@ static void free_qpn(struct hns_roce_dev *hr_dev, struct hns_roce_qp *hr_qp)
 
 	ida_free(&hr_dev->qp_table.bank[bankid].ida, hr_qp->qpn >> 3);
 
-	spin_lock(&hr_dev->qp_table.bank_lock);
+	mutex_lock(&hr_dev->qp_table.bank_mutex);
 	hr_dev->qp_table.bank[bankid].inuse--;
-	spin_unlock(&hr_dev->qp_table.bank_lock);
+	mutex_unlock(&hr_dev->qp_table.bank_mutex);
 }
 
 static int set_rq_size(struct hns_roce_dev *hr_dev, struct ib_qp_cap *cap,
@@ -1371,6 +1371,7 @@ int hns_roce_init_qp_table(struct hns_roce_dev *hr_dev)
 	unsigned int i;
 
 	mutex_init(&qp_table->scc_mutex);
+	mutex_init(&qp_table->bank_mutex);
 	xa_init(&hr_dev->qp_table_xa);
 
 	reserved_from_bot = hr_dev->caps.reserved_qps;
-- 
2.8.1

Re: [PATCH for-rc] RDMA/hns: Use mutex instead of spinlock for ida allocation

[Jason Gunthorpe]

On Tue, Jan 19, 2021 at 05:28:33PM +0800, Weihang Li wrote:
> From: Yangyang Li <liyangyang20@huawei.com>
> 
> GFP_KERNEL may cause ida_alloc_range() to sleep, but the spinlock covering
> this function is not allowed to sleep, so the spinlock needs to be changed
> to mutex.
> 
> As there is a certain chance of memory allocation failure, GFP_ATOMIC
> is not suitable for QP allocation scenarios.
> 
> Fixes: 71586dd20010 ("RDMA/hns: Create QP with selected QPN for bank load balance")
> Signed-off-by: Yangyang Li <liyangyang20@huawei.com>
> Signed-off-by: Weihang Li <liweihang@huawei.com>
> ---
>  drivers/infiniband/hw/hns/hns_roce_device.h |  2 +-
>  drivers/infiniband/hw/hns/hns_roce_qp.c     | 11 ++++++-----
>  2 files changed, 7 insertions(+), 6 deletions(-)

Applied to for-rc, thanks

Jason