validate_xmit_xfrm checks whether a packet already passed through it on the master device (xso.dev) and skips processing the skb again on the slave device (xso.real_dev).
This check was added in commit [1] to avoid tx packets on a bond device pass through xfrm twice and get two sets of headers, but the check was soon obsoleted by commit [2], which was added around the same time to fix a similar but unrelated problem. Commit [3] set XFRM_XMIT only when packets are hw offloaded.
xso.dev is usually equal to xso.real_dev, unless bonding is used, in which case the bonding driver uses xso.real_dev to manage offloaded xfrm states.
Since commit [3], the check added in commit [1] is unused on all cases, since packets going through validate_xmit_xfrm twice bail out on the check added in commit [2]. Here's a breakdown of relevant scenarios:
1. ESP offload off: validate_xmit_xfrm returns early on !xo. 2. ESP offload on, no bond: skb->dev == xso.real_dev == xso.dev. 3. ESP offload on, bond, xs on bond dev: 1st pass adds XFRM_XMIT, 2nd pass returns early on XFRM_XMIT. 3. ESP offload on, bond, xs on slave dev: 1st pass returns early on !xo, 2nd pass adds XFRM_XMIT. 4. ESP offload on, bond, xs on both bond AND slave dev: only 1 offload possible in secpath. Either 1st pass adds XFRM_XMIT and 2nd pass returns early on XFRM_XMIT, or 1st pass is sw and returns early on !xo. 6. ESP offload on, crypto fallback triggered in esp_xmit/esp6_xmit: 1st pass does sw crypto & secpath_reset, 2nd pass returns on !xo.
This commit removes the unnecessary check, so xso.real_dev becomes what it is in practice: a private field managed by bonding driver. The check immediately below that can be simplified as well.
[1] commit 272c2330adc9 ("xfrm: bail early on slave pass over skb") [2] commit 94579ac3f6d0 ("xfrm: Fix double ESP trailer insertion in IPsec crypto offload.") [3] commit c7dbf4c08868 ("xfrm: Provide private skb extensions for segmented and hw offloaded ESP packets")
Signed-off-by: Cosmin Ratiu cratiu@nvidia.com Reviewed-by: Leon Romanovsky leonro@nvidia.com --- net/xfrm/xfrm_device.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c index 4f4165ff738d..0be5f7ffd019 100644 --- a/net/xfrm/xfrm_device.c +++ b/net/xfrm/xfrm_device.c @@ -145,10 +145,6 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur return NULL; }
- /* This skb was already validated on the upper/virtual dev */ - if ((x->xso.dev != dev) && (x->xso.real_dev == dev)) - return skb; - local_irq_save(flags); sd = this_cpu_ptr(&softnet_data); err = !skb_queue_empty(&sd->xfrm_backlog); @@ -159,8 +155,7 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur return skb; }
- if (skb_is_gso(skb) && (unlikely(x->xso.dev != dev) || - unlikely(xmit_xfrm_check_overflow(skb)))) { + if (skb_is_gso(skb) && unlikely(xmit_xfrm_check_overflow(skb))) { struct sk_buff *segs;
/* Packet got rerouted, fixup features and segment it. */