[ofa-general] [PATCH 07/10] RDMA/nes: Check cqp_avail_reqs is empty after locking the list

[Chien Tung]

From: Faisal Latif <faisal.latif at intel.com>

RDMA/nes: Check cqp_avail_reqs is empty after locking the list

Between the first empty list check and locking the list, the list
can change.  Check it again after it is locked to make sure
the list is not empty.

Signed-off-by: Faisal Latif <faisal.latif at intel.com>
Signed-off-by: Chien Tung <chien.tin.tung at intel.com>
--
diff --git a/drivers/infiniband/hw/nes/nes_utils.c b/drivers/infiniband/hw/nes/nes_utils.c
index fb8cbd7..5611a73 100644
--- a/drivers/infiniband/hw/nes/nes_utils.c
+++ b/drivers/infiniband/hw/nes/nes_utils.c
@@ -540,11 +540,14 @@ struct nes_cqp_request *nes_get_cqp_request(struct nes_device *nesdev)
 
 	if (!list_empty(&nesdev->cqp_avail_reqs)) {
 		spin_lock_irqsave(&nesdev->cqp.lock, flags);
-		cqp_request = list_entry(nesdev->cqp_avail_reqs.next,
+		if (!list_empty(&nesdev->cqp_avail_reqs)) {
+			cqp_request = list_entry(nesdev->cqp_avail_reqs.next,
 				struct nes_cqp_request, list);
-		list_del_init(&cqp_request->list);
+			list_del_init(&cqp_request->list);
+		}
 		spin_unlock_irqrestore(&nesdev->cqp.lock, flags);
-	} else {
+	}
+	if (cqp_request == NULL) {
 		cqp_request = kzalloc(sizeof(struct nes_cqp_request), GFP_KERNEL);
 		if (cqp_request) {
 			cqp_request->dynamic = 1;