net: remove skb->vlan_present

skb->vlan_present seems redundant.

We can instead derive it from this boolean expression:

vlan_present = skb->vlan_proto != 0 || skb->vlan_tci != 0

Add a new union, to access both fields in a single load/store
when possible.

	union {
		u32	vlan_all;
		struct {
		__be16	vlan_proto;
		__u16	vlan_tci;
		};
	};

This allows following patch to remove a conditional test in GRO stack.

Note:
  We move remcsum_offload to keep TC_AT_INGRESS_MASK
  and SKB_MONO_DELIVERY_TIME_MASK unchanged.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 13 insertions, 14 deletions

diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index e00c4ee81ff7..6864b89ef868 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -76,7 +76,7 @@ static inline bool is_vlan_dev(const struct net_device *dev)
         return dev->priv_flags & IFF_802_1Q_VLAN;
 }
 
-#define skb_vlan_tag_present(__skb)	((__skb)->vlan_present)
+#define skb_vlan_tag_present(__skb)	(!!(__skb)->vlan_all)
 #define skb_vlan_tag_get(__skb)		((__skb)->vlan_tci)
 #define skb_vlan_tag_get_id(__skb)	((__skb)->vlan_tci & VLAN_VID_MASK)
 #define skb_vlan_tag_get_cfi(__skb)	(!!((__skb)->vlan_tci & VLAN_CFI_MASK))
@@ -471,7 +471,7 @@ static inline struct sk_buff *vlan_insert_tag_set_proto(struct sk_buff *skb,
  */
 static inline void __vlan_hwaccel_clear_tag(struct sk_buff *skb)
 {
-	skb->vlan_present = 0;
+	skb->vlan_all = 0;
 }
 
 /**
@@ -483,9 +483,7 @@ static inline void __vlan_hwaccel_clear_tag(struct sk_buff *skb)
  */
 static inline void __vlan_hwaccel_copy_tag(struct sk_buff *dst, const struct sk_buff *src)
 {
-	dst->vlan_present = src->vlan_present;
-	dst->vlan_proto = src->vlan_proto;
-	dst->vlan_tci = src->vlan_tci;
+	dst->vlan_all = src->vlan_all;
 }
 
 /*
@@ -519,7 +517,6 @@ static inline void __vlan_hwaccel_put_tag(struct sk_buff *skb,
 {
 	skb->vlan_proto = vlan_proto;
 	skb->vlan_tci = vlan_tci;
-	skb->vlan_present = 1;
 }
 
 /**
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 59c9fd55699d..4e464a27adaf 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -818,7 +818,7 @@ typedef unsigned char *sk_buff_data_t;
  *	@mark: Generic packet mark
  *	@reserved_tailroom: (aka @mark) number of bytes of free space available
  *		at the tail of an sk_buff
- *	@vlan_present: VLAN tag is present
+ *	@vlan_all: vlan fields (proto & tci)
  *	@vlan_proto: vlan encapsulation protocol
  *	@vlan_tci: vlan tag control information
  *	@inner_protocol: Protocol (encapsulation)
@@ -951,7 +951,7 @@ struct sk_buff {
 	/* private: */
 	__u8			__pkt_vlan_present_offset[0];
 	/* public: */
-	__u8			vlan_present:1;	/* See PKT_VLAN_PRESENT_BIT */
+	__u8			remcsum_offload:1;
 	__u8			csum_complete_sw:1;
 	__u8			csum_level:2;
 	__u8			dst_pending_confirm:1;
@@ -966,7 +966,6 @@ struct sk_buff {
 
 	__u8			ipvs_property:1;
 	__u8			inner_protocol_type:1;
-	__u8			remcsum_offload:1;
 #ifdef CONFIG_NET_SWITCHDEV
 	__u8			offload_fwd_mark:1;
 	__u8			offload_l3_fwd_mark:1;
@@ -999,8 +998,13 @@ struct sk_buff {
 	__u32			priority;
 	int			skb_iif;
 	__u32			hash;
-	__be16			vlan_proto;
-	__u16			vlan_tci;
+	union {
+		u32		vlan_all;
+		struct {
+			__be16	vlan_proto;
+			__u16	vlan_tci;
+		};
+	};
 #if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS)
 	union {
 		unsigned int	napi_id;
@@ -1059,15 +1063,13 @@ struct sk_buff {
 #endif
 #define PKT_TYPE_OFFSET		offsetof(struct sk_buff, __pkt_type_offset)
 
-/* if you move pkt_vlan_present, tc_at_ingress, or mono_delivery_time
+/* if you move tc_at_ingress or mono_delivery_time
  * around, you also must adapt these constants.
  */
 #ifdef __BIG_ENDIAN_BITFIELD
-#define PKT_VLAN_PRESENT_BIT	7
 #define TC_AT_INGRESS_MASK		(1 << 0)
 #define SKB_MONO_DELIVERY_TIME_MASK	(1 << 2)
 #else
-#define PKT_VLAN_PRESENT_BIT	0
 #define TC_AT_INGRESS_MASK		(1 << 7)
 #define SKB_MONO_DELIVERY_TIME_MASK	(1 << 5)
 #endif