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>

6 files changed, 41 insertions, 9 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,
diff --git a/include/net/sock.h b/include/net/sock.h
index 5edf0038867c..8b7ed7167243 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2697,7 +2697,7 @@ sock_recv_timestamp(struct msghdr *msg, struct sock *sk, struct sk_buff *skb)
 	else
 		sock_write_timestamp(sk, kt);
 
-	if (sock_flag(sk, SOCK_WIFI_STATUS) && skb->wifi_acked_valid)
+	if (sock_flag(sk, SOCK_WIFI_STATUS) && skb_wifi_acked_valid(skb))
 		__sock_recv_wifi_status(msg, sk, skb);
 }
 
diff --git a/net/core/dev.c b/net/core/dev.c
index 8aea68275172..3fc4dba71f9d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3315,8 +3315,7 @@ int skb_crc32c_csum_help(struct sk_buff *skb)
 						  skb->len - start, ~(__u32)0,
 						  crc32c_csum_stub));
 	*(__le32 *)(skb->data + offset) = crc32c_csum;
-	skb->ip_summed = CHECKSUM_NONE;
-	skb->csum_not_inet = 0;
+	skb_reset_csum_not_inet(skb);
 out:
 	return ret;
 }
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index ef81452759be..768f9d04911f 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5189,6 +5189,7 @@ void skb_tstamp_tx(struct sk_buff *orig_skb,
 }
 EXPORT_SYMBOL_GPL(skb_tstamp_tx);
 
+#ifdef CONFIG_WIRELESS
 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
 {
 	struct sock *sk = skb->sk;
@@ -5214,6 +5215,7 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
 		kfree_skb(skb);
 }
 EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
+#endif /* CONFIG_WIRELESS */
 
 /**
  * skb_partial_csum_set - set up and verify partial csum values for packet
diff --git a/net/sched/act_csum.c b/net/sched/act_csum.c
index 95e9304024b7..8ed285023a40 100644
--- a/net/sched/act_csum.c
+++ b/net/sched/act_csum.c
@@ -376,8 +376,7 @@ static int tcf_csum_sctp(struct sk_buff *skb, unsigned int ihl,
 
 	sctph->checksum = sctp_compute_cksum(skb,
 					     skb_network_offset(skb) + ihl);
-	skb->ip_summed = CHECKSUM_NONE;
-	skb->csum_not_inet = 0;
+	skb_reset_csum_not_inet(skb);
 
 	return 1;
 }
diff --git a/net/socket.c b/net/socket.c
index 73e493da4589..a7b4b37d86df 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -957,6 +957,7 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
 }
 EXPORT_SYMBOL_GPL(__sock_recv_timestamp);
 
+#ifdef CONFIG_WIRELESS
 void __sock_recv_wifi_status(struct msghdr *msg, struct sock *sk,
 	struct sk_buff *skb)
 {
@@ -972,6 +973,7 @@ void __sock_recv_wifi_status(struct msghdr *msg, struct sock *sk,
 	put_cmsg(msg, SOL_SOCKET, SCM_WIFI_STATUS, sizeof(ack), &ack);
 }
 EXPORT_SYMBOL_GPL(__sock_recv_wifi_status);
+#endif
 
 static inline void sock_recv_drops(struct msghdr *msg, struct sock *sk,
 				   struct sk_buff *skb)