xfrm: Remove xfrmi interface ID from flowi

In order to remove performance impact of having the extra u32 in every
single flowi, this change removes the flowi_xfrm struct, prefering to
take the if_id as a method parameter where needed.

In the inbound direction, if_id is only needed during the
__xfrm_check_policy() function, and the if_id can be determined at that
point based on the skb. As such, xfrmi_decode_session() is only called
with the skb in __xfrm_check_policy().

In the outbound direction, the only place where if_id is needed is the
xfrm_lookup() call in xfrmi_xmit2(). With this change, the if_id is
directly passed into the xfrm_lookup_with_ifid() call. All existing
callers can still call xfrm_lookup(), which uses a default if_id of 0.

This change does not change any behavior of XFRMIs except for improving
overall system performance via flowi size reduction.

This change has been tested against the Android Kernel Networking Tests:

https://android.googlesource.com/kernel/tests/+/master/net/test

Signed-off-by: Benedict Wong <benedictwong@google.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

3 files changed, 15 insertions, 10 deletions

diff --git a/include/net/dst.h b/include/net/dst.h
index b3219cd8a5a1..7f735e76ca73 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -475,6 +475,14 @@ static inline struct dst_entry *xfrm_lookup(struct net *net,
 	return dst_orig;
 }
 
+static inline struct dst_entry *
+xfrm_lookup_with_ifid(struct net *net, struct dst_entry *dst_orig,
+		      const struct flowi *fl, const struct sock *sk,
+		      int flags, u32 if_id)
+{
+	return dst_orig;
+}
+
 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
 						  struct dst_entry *dst_orig,
 						  const struct flowi *fl,
@@ -494,6 +502,12 @@ struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 			      const struct flowi *fl, const struct sock *sk,
 			      int flags);
 
+struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
+					struct dst_entry *dst_orig,
+					const struct flowi *fl,
+					const struct sock *sk, int flags,
+					u32 if_id);
+
 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
 				    const struct flowi *fl, const struct sock *sk,
 				    int flags);
diff --git a/include/net/flow.h b/include/net/flow.h
index 187c9bef672f..8ce21793094e 100644
--- a/include/net/flow.h
+++ b/include/net/flow.h
@@ -26,10 +26,6 @@ struct flowi_tunnel {
 	__be64			tun_id;
 };
 
-struct flowi_xfrm {
-	__u32			if_id;
-};
-
 struct flowi_common {
 	int	flowic_oif;
 	int	flowic_iif;
@@ -43,7 +39,6 @@ struct flowi_common {
 #define FLOWI_FLAG_SKIP_NH_OIF		0x04
 	__u32	flowic_secid;
 	struct flowi_tunnel flowic_tun_key;
-	struct flowi_xfrm xfrm;
 	kuid_t  flowic_uid;
 };
 
@@ -83,7 +78,6 @@ struct flowi4 {
 #define flowi4_secid		__fl_common.flowic_secid
 #define flowi4_tun_key		__fl_common.flowic_tun_key
 #define flowi4_uid		__fl_common.flowic_uid
-#define flowi4_xfrm		__fl_common.xfrm
 
 	/* (saddr,daddr) must be grouped, same order as in IP header */
 	__be32			saddr;
@@ -115,7 +109,6 @@ static inline void flowi4_init_output(struct flowi4 *fl4, int oif,
 	fl4->flowi4_flags = flags;
 	fl4->flowi4_secid = 0;
 	fl4->flowi4_tun_key.tun_id = 0;
-	fl4->flowi4_xfrm.if_id = 0;
 	fl4->flowi4_uid = uid;
 	fl4->daddr = daddr;
 	fl4->saddr = saddr;
@@ -145,7 +138,6 @@ struct flowi6 {
 #define flowi6_secid		__fl_common.flowic_secid
 #define flowi6_tun_key		__fl_common.flowic_tun_key
 #define flowi6_uid		__fl_common.flowic_uid
-#define flowi6_xfrm		__fl_common.xfrm
 	struct in6_addr		daddr;
 	struct in6_addr		saddr;
 	/* Note: flowi6_tos is encoded in flowlabel, too. */
@@ -193,7 +185,6 @@ struct flowi {
 #define flowi_secid	u.__fl_common.flowic_secid
 #define flowi_tun_key	u.__fl_common.flowic_tun_key
 #define flowi_uid	u.__fl_common.flowic_uid
-#define flowi_xfrm	u.__fl_common.xfrm
 } __attribute__((__aligned__(BITS_PER_LONG/8)));
 
 static inline struct flowi *flowi4_to_flowi(struct flowi4 *fl4)
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 1350e2cf0749..ca820945f30c 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1557,7 +1557,7 @@ struct xfrm_state *xfrm_state_find(const xfrm_address_t *daddr,
 				   const struct flowi *fl,
 				   struct xfrm_tmpl *tmpl,
 				   struct xfrm_policy *pol, int *err,
-				   unsigned short family);
+				   unsigned short family, u32 if_id);
 struct xfrm_state *xfrm_stateonly_find(struct net *net, u32 mark, u32 if_id,
 				       xfrm_address_t *daddr,
 				       xfrm_address_t *saddr,