Merge branch 'skbuff-bitfields'

Jakub Kicinski says:

====================
net: skbuff: hide some bitfield members

There is a number of protocol or subsystem specific fields
in struct sk_buff which are only accessed by one subsystem.
We can wrap them in ifdefs with minimal code impact.

This gives us a better chance to save a 2B and a 4B holes
resulting with the following savings (assuming a lucky
kernel config):

-	/* size: 232, cachelines: 4, members: 28 */
-	/* sum members: 227, holes: 1, sum holes: 4 */
-	/* sum bitfield members: 8 bits (1 bytes) */
+	/* size: 224, cachelines: 4, members: 28 */
 	/* forced alignments: 2 */
-	/* last cacheline: 40 bytes */
+	/* last cacheline: 32 bytes */

I think that the changes shouldn't be too controversial.
The only one I'm not 100% sure of is the SCTP one,
12 extra LoC for one bit.. But it did fit squarely
in the "this bit has only one user" category.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Simon Horman <horms@kernel.org>

1 files changed, 34 insertions, 4 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index a823ec3aa326..5f120bbab9da 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -934,7 +934,7 @@ struct sk_buff {
 	/* public: */
 	__u8			pkt_type:3; /* see PKT_TYPE_MAX */
 	__u8			ignore_df:1;
-	__u8			nf_trace:1;
+	__u8			dst_pending_confirm:1;
 	__u8			ip_summed:2;
 	__u8			ooo_okay:1;
 
@@ -949,12 +949,14 @@ struct sk_buff {
 	__u8			remcsum_offload:1;
 	__u8			csum_complete_sw:1;
 	__u8			csum_level:2;
-	__u8			dst_pending_confirm:1;
+	__u8			inner_protocol_type:1;
 
 	__u8			l4_hash:1;
 	__u8			sw_hash:1;
+#ifdef CONFIG_WIRELESS
 	__u8			wifi_acked_valid:1;
 	__u8			wifi_acked:1;
+#endif
 	__u8			no_fcs:1;
 	/* Indicates the inner headers are valid in the skbuff. */
 	__u8			encapsulation:1;
@@ -964,8 +966,12 @@ struct sk_buff {
 	__u8			ndisc_nodetype:2;
 #endif
 
+#if IS_ENABLED(CONFIG_IP_VS)
 	__u8			ipvs_property:1;
-	__u8			inner_protocol_type:1;
+#endif
+#if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || IS_ENABLED(CONFIG_NF_TABLES)
+	__u8			nf_trace:1;
+#endif
 #ifdef CONFIG_NET_SWITCHDEV
 	__u8			offload_fwd_mark:1;
 	__u8			offload_l3_fwd_mark:1;
@@ -981,12 +987,16 @@ struct sk_buff {
 	__u8			decrypted:1;
 #endif
 	__u8			slow_gro:1;
+#if IS_ENABLED(CONFIG_IP_SCTP)
 	__u8			csum_not_inet:1;
+#endif
 
 #ifdef CONFIG_NET_SCHED
 	__u16			tc_index;	/* traffic control index */
 #endif
 
+	u16			alloc_cpu;
+
 	union {
 		__wsum		csum;
 		struct {
@@ -1010,7 +1020,6 @@ struct sk_buff {
 		unsigned int	sender_cpu;
 	};
 #endif
-	u16			alloc_cpu;
 #ifdef CONFIG_NETWORK_SECMARK
 	__u32		secmark;
 #endif
@@ -1187,6 +1196,15 @@ static inline unsigned int skb_napi_id(const struct sk_buff *skb)
 #endif
 }
 
+static inline bool skb_wifi_acked_valid(const struct sk_buff *skb)
+{
+#ifdef CONFIG_WIRELESS
+	return skb->wifi_acked_valid;
+#else
+	return 0;
+#endif
+}
+
 /**
  * skb_unref - decrement the skb's reference count
  * @skb: buffer
@@ -5049,7 +5067,19 @@ static inline void skb_reset_redirect(struct sk_buff *skb)
 
 static inline bool skb_csum_is_sctp(struct sk_buff *skb)
 {
+#if IS_ENABLED(CONFIG_IP_SCTP)
 	return skb->csum_not_inet;
+#else
+	return 0;
+#endif
+}
+
+static inline void skb_reset_csum_not_inet(struct sk_buff *skb)
+{
+	skb->ip_summed = CHECKSUM_NONE;
+#if IS_ENABLED(CONFIG_IP_SCTP)
+	skb->csum_not_inet = 0;
+#endif
 }
 
 static inline void skb_set_kcov_handle(struct sk_buff *skb,