diff mbox series

[net-next,RFC,v1,4/4] veth: when XDP is loaded increase needed_headroom

Message ID 169272716651.1975370.10514711233878278884.stgit@firesoul (mailing list archive)
State RFC
Delegated to: Netdev Maintainers
Headers show
Series veth: reduce reallocations of SKBs when XDP bpf-prog is loaded | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1330 this patch: 1330
netdev/cc_maintainers warning 4 maintainers not CCed: daniel@iogearbox.net ast@kernel.org bpf@vger.kernel.org john.fastabend@gmail.com
netdev/build_clang success Errors and warnings before: 1353 this patch: 1353
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1353 this patch: 1353
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 14 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Jesper Dangaard Brouer Aug. 22, 2023, 5:59 p.m. UTC 
When sending (sendmsg) SKBs out an veth device, the SKB headroom is too small
to satisfy XDP on the receiving veth peer device.

For AF_XDP (normal non-zero-copy) it is worth noticing that xsk_build_skb()
adjust headroom according to dev->needed_headroom. Other parts of the kernel
also take this into account (see macro LL_RESERVED_SPACE).

This solves the XDP_PACKET_HEADROOM check in veth_convert_skb_to_xdp_buff().

Signed-off-by: Jesper Dangaard Brouer <hawk@kernel.org>
---
 drivers/net/veth.c |    2 ++
 1 file changed, 2 insertions(+)
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Patch

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 8e117cc44fda..3630e9124071 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -1649,6 +1649,7 @@  static int veth_xdp_set(struct net_device *dev, struct bpf_prog *prog,
 		if (!old_prog) {
 			peer->hw_features &= ~NETIF_F_GSO_SOFTWARE;
 			peer->max_mtu = max_mtu;
+			veth_set_rx_headroom(dev, XDP_PACKET_HEADROOM);
 		}
 
 		xdp_features_set_redirect_target(peer, true);
@@ -1666,6 +1667,7 @@  static int veth_xdp_set(struct net_device *dev, struct bpf_prog *prog,
 				peer->hw_features |= NETIF_F_GSO_SOFTWARE;
 				peer->max_mtu = ETH_MAX_MTU;
 			}
+			veth_set_rx_headroom(dev, -1);
 		}
 		bpf_prog_put(old_prog);
 	}