On Sun, Aug 31, 2025 at 06:35:49PM +0300, Ido Schimmel wrote:
diff --git a/net/core/dev.c b/net/core/dev.c index 1d1650d9ecff..fcad2a9f6b65 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -12577,6 +12577,85 @@ netdev_features_t netdev_increment_features(netdev_features_t all, } EXPORT_SYMBOL(netdev_increment_features); +/**
- netdev_compute_features_from_lowers - compute feature from lowers
- @dev: the upper device
- Recompute the upper device's feature based on all lower devices.
- */
+void netdev_compute_features_from_lowers(struct net_device *dev) +{
- unsigned int dst_release_flag = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
- netdev_features_t gso_partial_features = VIRTUAL_DEV_GSO_PARTIAL_FEATURES;
+#ifdef CONFIG_XFRM_OFFLOAD
- netdev_features_t xfrm_features = VIRTUAL_DEV_XFRM_FEATURES;
^ double space (in other places as well)+#endif
- netdev_features_t mpls_features = VIRTUAL_DEV_MPLS_FEATURES;
- netdev_features_t vlan_features = VIRTUAL_DEV_VLAN_FEATURES;
- netdev_features_t enc_features = VIRTUAL_DEV_ENC_FEATURES;
- unsigned short max_hard_header_len = ETH_HLEN;
hard_header_len is not really a feature, so does not sound like it belongs here. I'm pretty sure it's not needed at all.
It was added to the bond driver in 2006 by commit 54ef31371407 ("[PATCH] bonding: Handle large hard_header_len") citing panics with gianfar on xmit. In 2009 commit 93c1285c5d92 ("gianfar: reallocate skb when headroom is not enough for fcb") fixed the gianfar driver to stop assuming that it has enough room to push its custom header. Further, commit bee9e58c9e98 ("gianfar:don't add FCB length to hard_header_len") from 2012 fixed this driver to use needed_headroom instead of hard_header_len.
Wow, thanks a lot for the long history changes..
The team driver is also adjusting hard_header_len according to the lower devices, but it most likely copied it from the bond driver. On the other hand, the bridge driver does not mess with hard_header_len and no problems were reported there (that I know of).
Might be a good idea to remove this hard_header_len logic from bond and team and instead set their needed_headroom according to the lower device with the highest needed_headroom. Paolo added similar logic in bridge and ovs but the use case is a bit different there.
OK, I will get the highest needed_headroom for each slave and set the minimal one to upper device.
Regards Hangbin