From 958b3d396d7f80755e2c2e6a8f873a669f38de10 Mon Sep 17 00:00:00 2001 From: Brenden Blanco Date: Thu, 13 Oct 2016 13:13:11 -0700 Subject: [PATCH] net/mlx4_en: fixup xdp tx irq to match rx In cases where the number of tx rings is not a multiple of the number of rx rings, the tx completion event will be handled on a different core from the transmit and population of the ring. Races on the ring will lead to a double-free of the page, and possibly other corruption. The rings are initialized by default with a valid multiple of rings, based on the number of cpus, therefore an invalid configuration requires ethtool to change the ring layout. For instance 'ethtool -L eth0 rx 9 tx 8' will cause packets received on rx0, and XDP_TX'd to tx48, to be completed on cpu3 (48 % 9 == 3). Resolve this discrepancy by shifting the irq for the xdp tx queues to start again from 0, modulo rx_ring_num. Fixes: 9ecc2d86171a ("net/mlx4_en: add xdp forwarding and data write support") Reported-by: Jesper Dangaard Brouer Signed-off-by: Brenden Blanco Signed-off-by: David S. Miller --- drivers/net/ethernet/mellanox/mlx4/en_cq.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/en_cq.c b/drivers/net/ethernet/mellanox/mlx4/en_cq.c index 132cea655920..e3be7e44ff51 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_cq.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_cq.c @@ -127,7 +127,15 @@ int mlx4_en_activate_cq(struct mlx4_en_priv *priv, struct mlx4_en_cq *cq, /* For TX we use the same irq per ring we assigned for the RX */ struct mlx4_en_cq *rx_cq; - + int xdp_index; + + /* The xdp tx irq must align with the rx ring that forwards to + * it, so reindex these from 0. This should only happen when + * tx_ring_num is not a multiple of rx_ring_num. + */ + xdp_index = (priv->xdp_ring_num - priv->tx_ring_num) + cq_idx; + if (xdp_index >= 0) + cq_idx = xdp_index; cq_idx = cq_idx % priv->rx_ring_num; rx_cq = priv->rx_cq[cq_idx]; cq->vector = rx_cq->vector; -- 2.20.1