[dpdk-dev] [PATCH 24/25] net/mlx5: make VLAN network interface thread safe

[Suanming Mou]

This commit takes advantage of the atomic operation with the VLAN VM
workaround object reference count to make sure the object to be thread
safe and not to be created or destroyed in parallel.

Signed-off-by: Suanming Mou <suanmingm at nvidia.com>
---
 drivers/net/mlx5/linux/mlx5_vlan_os.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/net/mlx5/linux/mlx5_vlan_os.c b/drivers/net/mlx5/linux/mlx5_vlan_os.c
index 92fc17d..00e160f 100644
--- a/drivers/net/mlx5/linux/mlx5_vlan_os.c
+++ b/drivers/net/mlx5/linux/mlx5_vlan_os.c
@@ -45,10 +45,11 @@
 		return;
 	vlan->created = 0;
 	MLX5_ASSERT(vlan_dev[vlan->tag].refcnt);
-	if (--vlan_dev[vlan->tag].refcnt == 0 &&
-	    vlan_dev[vlan->tag].ifindex) {
+	if (!__atomic_sub_fetch(&vlan_dev[vlan->tag].refcnt,
+	    1, __ATOMIC_RELAXED)) {
 		mlx5_nl_vlan_vmwa_delete(vmwa, vlan_dev[vlan->tag].ifindex);
-		vlan_dev[vlan->tag].ifindex = 0;
+		__atomic_store_n(&vlan_dev[vlan->tag].ifindex,
+				 0, __ATOMIC_RELAXED);
 	}
 }
 
@@ -72,16 +73,21 @@
 	MLX5_ASSERT(priv->vmwa_context);
 	if (vlan->created || !vmwa)
 		return;
-	if (vlan_dev[vlan->tag].refcnt == 0) {
-		MLX5_ASSERT(!vlan_dev[vlan->tag].ifindex);
+	if (__atomic_add_fetch
+	    (&vlan_dev[vlan->tag].refcnt, 1, __ATOMIC_RELAXED) == 1) {
+		/* Make sure ifindex is destroyed. */
+		rte_wait_until_equal_32(&vlan_dev[vlan->tag].ifindex,
+					0, __ATOMIC_RELAXED);
 		vlan_dev[vlan->tag].ifindex =
 			mlx5_nl_vlan_vmwa_create(vmwa, vmwa->vf_ifindex,
 						 vlan->tag);
+		if (!vlan_dev[vlan->tag].ifindex) {
+			__atomic_store_n(&vlan_dev[vlan->tag].refcnt,
+					 0, __ATOMIC_RELAXED);
+			return;
+		}
 	}
-	if (vlan_dev[vlan->tag].ifindex) {
-		vlan_dev[vlan->tag].refcnt++;
-		vlan->created = 1;
-	}
+	vlan->created = 1;
 }
 
 /*
-- 
1.8.3.1