queue-6.19/net-introduce-mangleid_features.patch

From dc7f820a49b671493cb743d81d995ccd5eecf2f8 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Wed, 21 Jan 2026 17:11:27 +0100
Subject: net: introduce mangleid_features

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 1216f050f0699..846afec74703b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1833,6 +1833,8 @@ 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
@@ -2222,6 +2224,7 @@ 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 b5f0d5c4d5412..8439bac371b7d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3819,7 +3819,7 @@ 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,
@@ -11411,6 +11411,9 @@ 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