On Fri, Aug 29, 2025 at 09:54:26AM +0000, Hangbin Liu wrote:
Some high level virtual drivers need to compute features from lower devices. But each has their own implementations and may lost some feature compute. Let's use one common function to compute features for kinds of these devices.
The new helper uses the current bond implementation as the reference one, as the latter already handles all the relevant aspects: netdev features, TSO limits and dst retention.
Suggested-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Hangbin Liu liuhangbin@gmail.com
include/linux/netdevice.h | 19 ++++++++++ net/core/dev.c | 79 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 98 insertions(+)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index f3a3b761abfb..42742a47f2c6 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -5279,6 +5279,25 @@ int __netdev_update_features(struct net_device *dev); void netdev_update_features(struct net_device *dev); void netdev_change_features(struct net_device *dev); +/* netdevice features */ +#define VIRTUAL_DEV_VLAN_FEATURES (NETIF_F_HW_CSUM | NETIF_F_SG | \
NETIF_F_FRAGLIST | NETIF_F_GSO_SOFTWARE | \NETIF_F_GSO_ENCAP_ALL | \NETIF_F_HIGHDMA | NETIF_F_LRO)+#define VIRTUAL_DEV_ENC_FEATURES (NETIF_F_HW_CSUM | NETIF_F_SG | \
NETIF_F_RXCSUM | NETIF_F_GSO_SOFTWARE | \NETIF_F_GSO_PARTIAL)+#define VIRTUAL_DEV_MPLS_FEATURES (NETIF_F_HW_CSUM | NETIF_F_SG | \
NETIF_F_GSO_SOFTWARE)+#define VIRTUAL_DEV_XFRM_FEATURES (NETIF_F_HW_ESP | NETIF_F_HW_ESP_TX_CSUM | \
NETIF_F_GSO_ESP)+#define VIRTUAL_DEV_GSO_PARTIAL_FEATURES (NETIF_F_GSO_ESP) +void netdev_compute_features_from_lowers(struct net_device *dev);
void netif_stacked_transfer_operstate(const struct net_device *rootdev, struct net_device *dev); 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.
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.
- unsigned int tso_max_size = TSO_MAX_SIZE;
- u16 tso_max_segs = TSO_MAX_SEGS;
- struct net_device *lower_dev;
- struct list_head *iter;
- mpls_features = netdev_base_features(mpls_features);
- vlan_features = netdev_base_features(vlan_features);
- enc_features = netdev_base_features(enc_features);
- netdev_for_each_lower_dev(dev, lower_dev, iter) {
gso_partial_features = netdev_increment_features(gso_partial_features,lower_dev->gso_partial_features,VIRTUAL_DEV_GSO_PARTIAL_FEATURES);vlan_features = netdev_increment_features(vlan_features,lower_dev->vlan_features,VIRTUAL_DEV_VLAN_FEATURES);+#ifdef CONFIG_XFRM_OFFLOAD
xfrm_features = netdev_increment_features(xfrm_features,lower_dev->hw_enc_features,VIRTUAL_DEV_XFRM_FEATURES);+#endif
enc_features = netdev_increment_features(enc_features,lower_dev->hw_enc_features,VIRTUAL_DEV_ENC_FEATURES);mpls_features = netdev_increment_features(mpls_features,lower_dev->mpls_features,VIRTUAL_DEV_MPLS_FEATURES);dst_release_flag &= lower_dev->priv_flags;if (lower_dev->hard_header_len > max_hard_header_len)max_hard_header_len = lower_dev->hard_header_len;tso_max_size = min(tso_max_size, lower_dev->tso_max_size);tso_max_segs = min(tso_max_segs, lower_dev->tso_max_segs);- }
- dev->gso_partial_features = gso_partial_features;
- dev->hard_header_len = max_hard_header_len;
- dev->vlan_features = vlan_features;
- dev->hw_enc_features = enc_features | NETIF_F_GSO_ENCAP_ALL |
NETIF_F_HW_VLAN_CTAG_TX |NETIF_F_HW_VLAN_STAG_TX;+#ifdef CONFIG_XFRM_OFFLOAD
- dev->hw_enc_features |= xfrm_features;
+#endif
- dev->mpls_features = mpls_features;
- netif_set_tso_max_segs(dev, tso_max_segs);
- netif_set_tso_max_size(dev, tso_max_size);
- dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
- if ((dev->priv_flags & IFF_XMIT_DST_RELEASE_PERM) &&
dst_release_flag == (IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM))dev->priv_flags |= IFF_XMIT_DST_RELEASE;- netdev_change_features(dev);
+} +EXPORT_SYMBOL(netdev_compute_features_from_lowers);
static struct hlist_head * __net_init netdev_create_hash(void) { int i; -- 2.50.1