[PATCH net-next 1/3] net/mlx4_en: use READ_ONCE when freeing xdp_prog

[Brenden Blanco]

For consistency, and in order to hint at the synchronous nature of the
xdp_prog field, use READ_ONCE in the destroy path of the ring. All
occurrences should now use either READ_ONCE or xchg.

Signed-off-by: Brenden Blanco <bbla...@plumgrid.com>
---
 drivers/net/ethernet/mellanox/mlx4/en_rx.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c 
b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 11d88c8..a02dec6 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -535,9 +535,11 @@ void mlx4_en_destroy_rx_ring(struct mlx4_en_priv *priv,
 {
        struct mlx4_en_dev *mdev = priv->mdev;
        struct mlx4_en_rx_ring *ring = *pring;
+       struct bpf_prog *old_prog;
 
-       if (ring->xdp_prog)
-               bpf_prog_put(ring->xdp_prog);
+       old_prog = READ_ONCE(ring->xdp_prog);
+       if (old_prog)
+               bpf_prog_put(old_prog);
        mlx4_free_hwq_res(mdev->dev, &ring->wqres, size * stride + TXBB_SIZE);
        vfree(ring->rx_info);
        ring->rx_info = NULL;
-- 
2.8.2