netdev - [PATCH RFC 8/9] sk_buff: move vlan field after tail.

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Date:   Wed, 21 Jul 2021 18:44:40 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     netdev@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Florian Westphal <fw@...len.de>,
        Eric Dumazet <edumazet@...gle.com>,
        linux-security-module@...r.kernel.org, selinux@...r.kernel.org
Subject: [PATCH RFC 8/9] sk_buff: move vlan field after tail.

Such field validity is already tracked by the existing
'vlan_present' bit. Move them after tail and conditinally copy
as needed.

Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
 include/linux/skbuff.h | 10 ++++++++--
 net/core/skbuff.c      |  5 +++--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index a3e756575aa7..7acf2a203918 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -897,8 +897,6 @@ struct sk_buff {
 	__u32			priority;
 	int			skb_iif;
 	__u32			hash;
-	__be16			vlan_proto;
-	__u16			vlan_tci;
 #if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS)
 	union {
 		unsigned int	napi_id;
@@ -955,6 +953,14 @@ struct sk_buff {
 		};
 		__u64		inner_headers;
 	};
+
+	union {
+		struct {
+			__be16	vlan_proto;
+			__u16	vlan_tci;
+		};
+		__u32		vlan_info;
+	};
 };
 
 #ifdef __KERNEL__
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 53b8db10e567..c59e90db80d5 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -996,6 +996,8 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 	__skb_ext_copy(new, old);
 	__nf_copy(new, old, false);
 	__skb_copy_inner_headers(new, old);
+	if (old->vlan_present)
+		new->vlan_info = old->vlan_info;
 
 	/* Note : this field could be in headers_start/headers_end section
 	 * It is not yet because we do not want to have a 16 bit hole
@@ -1007,13 +1009,12 @@ static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 	       offsetof(struct sk_buff, headers_start));
 	CHECK_SKB_FIELD(_state);
 	CHECK_SKB_FIELD(__pkt_encapsulation_offset);
+	CHECK_SKB_FIELD(__pkt_vlan_present_offset);
 	CHECK_SKB_FIELD(protocol);
 	CHECK_SKB_FIELD(csum);
 	CHECK_SKB_FIELD(hash);
 	CHECK_SKB_FIELD(priority);
 	CHECK_SKB_FIELD(skb_iif);
-	CHECK_SKB_FIELD(vlan_proto);
-	CHECK_SKB_FIELD(vlan_tci);
 	CHECK_SKB_FIELD(transport_header);
 	CHECK_SKB_FIELD(network_header);
 	CHECK_SKB_FIELD(mac_header);
-- 
2.26.3