[PATCH 6.12 060/242] net: introduce mangleid_features

Greg Kroah-Hartman
2026-04-08T18:41:52Z

From: Paolo Abeni <pabeni@redhat.com>

[ Upstream commit 31c5a71d982b57df75858974634c2f0a338f2fc6 ]

Some/most devices implementing gso_partial need to disable the GSO partial
features when the IP ID can't be mangled; to that extend each of them
implements something alike the following[1]:

if (skb->encapsulation && !(features & NETIF_F_TSO_MANGLEID))
features &= ~NETIF_F_TSO;

in the ndo_features_check() op, which leads to a bit of duplicate code.

Later patch in the series will implement GSO partial support for virtual
devices, and the current status quo will require more duplicate code and
a new indirect call in the TX path for them.

Introduce the mangleid_features mask, allowing the core to disable NIC
features based on/requiring MANGLEID, without any further intervention
from the driver.

The same functionality could be alternatively implemented adding a single
boolean flag to the struct net_device, but would require an additional
checks in ndo_features_check().

Also note that [1] is incorrect if the NIC additionally implements
NETIF_F_GSO_UDP_L4, mangleid_features transparently handle even such a
case.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/5a7cdaeea40b0a29b88e525b6c942d73ed3b8ce7.1769011015.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: ddc748a391dd ("net: use skb_header_pointer() for TCPv4 GSO frag_off check")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/netdevice.h | 3 +++
net/core/dev.c | 5 ++++-
2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index fcc1509ca7cb8..ea9b40b196de2 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1760,6 +1760,8 @@ enum netdev_reg_state {
*
* @mpls_features: Mask of features inheritable by MPLS
* @gso_partial_features: value(s) from NETIF_F_GSO\*
+ * @mangleid_features: Mask of features requiring MANGLEID, will be
+ * disabled together with the latter.
*
* @ifindex: interface index
* @group: The group the device belongs to
@@ -2133,6 +2135,7 @@ struct net_device {
netdev_features_t vlan_features;
netdev_features_t hw_enc_features;
netdev_features_t mpls_features;
+ netdev_features_t mangleid_features;

unsigned int min_mtu;
unsigned int max_mtu;
diff --git a/net/core/dev.c b/net/core/dev.c
index 336257b515f04..2748ee051bd1b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3613,7 +3613,7 @@ static netdev_features_t gso_features_check(const struct sk_buff *skb,
inner_ip_hdr(skb) : ip_hdr(skb);

if (!(iph->frag_off & htons(IP_DF)))
- features &= ~NETIF_F_TSO_MANGLEID;
+ features &= ~dev->mangleid_features;
}

/* NETIF_F_IPV6_CSUM does not support IPv6 extension headers,
@@ -10579,6 +10579,9 @@ int register_netdevice(struct net_device *dev)
if (dev->hw_enc_features & NETIF_F_TSO)
dev->hw_enc_features |= NETIF_F_TSO_MANGLEID;

+ /* TSO_MANGLEID belongs in mangleid_features by definition */
+ dev->mangleid_features |= NETIF_F_TSO_MANGLEID;
+
/* Make NETIF_F_HIGHDMA inheritable to VLAN devices.
*/
dev->vlan_features |= NETIF_F_HIGHDMA;
--
2.53.0