From d7db7775ea2e31502d46427f5efd385afc4ff1eb Mon Sep 17 00:00:00 2001 From: Ignat Korchagin Date: Wed, 13 Mar 2024 19:37:58 +0100 Subject: [PATCH] net: veth: do not manipulate GRO when using XDP MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit d3256efd8e8b ("veth: allow enabling NAPI even without XDP") tried to fix the fact that GRO was not possible without XDP, because veth did not use NAPI without XDP. However, it also introduced the behaviour that GRO is always enabled, when XDP is enabled. While it might be desired for most cases, it is confusing for the user at best as the GRO flag suddenly changes, when an XDP program is attached. It also introduces some complexities in state management as was partially addressed in commit fe9f801355f0 ("net: veth: clear GRO when clearing XDP even when down"). But the biggest problem is that it is not possible to disable GRO at all, when an XDP program is attached, which might be needed for some use cases. Fix this by not touching the GRO flag on XDP enable/disable as the code already supports switching to NAPI if either GRO or XDP is requested. Link: https://lore.kernel.org/lkml/20240311124015.38106-1-ignat@cloudflare.com/ Fixes: d3256efd8e8b ("veth: allow enabling NAPI even without XDP") Fixes: fe9f801355f0 ("net: veth: clear GRO when clearing XDP even when down") Signed-off-by: Ignat Korchagin Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: David S. Miller --- drivers/net/veth.c | 18 ------------------ 1 file changed, 18 deletions(-) diff --git a/drivers/net/veth.c b/drivers/net/veth.c index 13d902462d8e..bcdfbf61eb66 100644 --- a/drivers/net/veth.c +++ b/drivers/net/veth.c @@ -1464,8 +1464,6 @@ static netdev_features_t veth_fix_features(struct net_device *dev, if (peer_priv->_xdp_prog) features &= ~NETIF_F_GSO_SOFTWARE; } - if (priv->_xdp_prog) - features |= NETIF_F_GRO; return features; } @@ -1569,14 +1567,6 @@ static int veth_xdp_set(struct net_device *dev, struct bpf_prog *prog, } if (!old_prog) { - if (!veth_gro_requested(dev)) { - /* user-space did not require GRO, but adding - * XDP is supposed to get GRO working - */ - dev->features |= NETIF_F_GRO; - netdev_features_change(dev); - } - peer->hw_features &= ~NETIF_F_GSO_SOFTWARE; peer->max_mtu = max_mtu; } @@ -1592,14 +1582,6 @@ static int veth_xdp_set(struct net_device *dev, struct bpf_prog *prog, if (dev->flags & IFF_UP) veth_disable_xdp(dev); - /* if user-space did not require GRO, since adding XDP - * enabled it, clear it now - */ - if (!veth_gro_requested(dev)) { - dev->features &= ~NETIF_F_GRO; - netdev_features_change(dev); - } - if (peer) { peer->hw_features |= NETIF_F_GSO_SOFTWARE; peer->max_mtu = ETH_MAX_MTU;