Eric points out that we should make sure that ring index updates
are wrapped in the appropriate READ_ONCE/WRITE_ONCE macros.
Suggested-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
---
CC: tariqt@xxxxxxxxxx
CC: linux-rdma@xxxxxxxxxxxxxxx
---
drivers/net/ethernet/mellanox/mlx4/en_tx.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
index 2f79378fbf6e..65cb63f6c465 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
@@ -228,7 +228,9 @@ void mlx4_en_deactivate_tx_ring(struct mlx4_en_priv *priv,
static inline bool mlx4_en_is_tx_ring_full(struct mlx4_en_tx_ring *ring)
{
- return ring->prod - ring->cons > ring->full_size;
+ u32 used = READ_ONCE(ring->prod) - READ_ONCE(ring->cons);
+
+ return used > ring->full_size;
}
static void mlx4_en_stamp_wqe(struct mlx4_en_priv *priv,
@@ -1083,7 +1085,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
op_own |= cpu_to_be32(MLX4_WQE_CTRL_IIP);
}
- ring->prod += nr_txbb;
+ WRITE_ONCE(ring->prod, ring->prod + nr_txbb);
/* If we used a bounce buffer then copy descriptor back into place */
if (unlikely(bounce))
@@ -1214,7 +1216,7 @@ netdev_tx_t mlx4_en_xmit_frame(struct mlx4_en_rx_ring *rx_ring,
rx_ring->xdp_tx++;
- ring->prod += MLX4_EN_XDP_TX_NRTXBB;
+ WRITE_ONCE(ring->prod, ring->prod + MLX4_EN_XDP_TX_NRTXBB);
/* Ensure new descriptor hits memory
* before setting ownership of this descriptor to HW
--
2.39.2
