net: Get skb hash over flow_keys structure

This patch changes flow hashing to use jhash2 over the flow_keys
structure instead just doing jhash_3words over src, dst, and ports.
This method will allow us take more input into the hashing function
so that we can include full IPv6 addresses, VLAN, flow labels etc.
without needing to resort to xor'ing which makes for a poor hash.

Acked-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6b41c15efa277f414d825a5042ebd7b259d66ac5..cc612fc0a8943ec853b92e6b3516b0e5582299e2 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1943,7 +1943,7 @@ static inline void skb_probe_transport_header(struct sk_buff *skb,
        if (skb_transport_header_was_set(skb))
                return;
        else if (skb_flow_dissect_flow_keys(skb, &keys))
-               skb_set_transport_header(skb, keys.basic.thoff);
+               skb_set_transport_header(skb, keys.control.thoff);
        else
                skb_set_transport_header(skb, offset_hint);
 }

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index bac9c1421f580a12d313ac1fdbb98d7e96a05d85..cba6a10b214a6b92177881b8a4192396a7aeb74a 100644 (file)
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -6,6 +6,15 @@
 #include <linux/in6.h>
 #include <uapi/linux/if_ether.h>
 
+/**
+ * struct flow_dissector_key_control:
+ * @thoff: Transport header offset
+ */
+struct flow_dissector_key_control {
+       u16     thoff;
+       u16     padding;
+};
+
 /**
  * struct flow_dissector_key_basic:
  * @thoff: Transport header offset
@@ -13,9 +22,9 @@
  * @ip_proto: Transport header protocol (eg. TCP/UDP)
  */
 struct flow_dissector_key_basic {
-       u16     thoff;
        __be16  n_proto;
        u8      ip_proto;
+       u8      padding;
 };
 
 /**
@@ -70,6 +79,7 @@ struct flow_dissector_key_eth_addrs {
 };
 
 enum flow_dissector_key_id {
+       FLOW_DISSECTOR_KEY_CONTROL, /* struct flow_dissector_key_control */
        FLOW_DISSECTOR_KEY_BASIC, /* struct flow_dissector_key_basic */
        FLOW_DISSECTOR_KEY_IPV4_ADDRS, /* struct flow_dissector_key_addrs */
        FLOW_DISSECTOR_KEY_IPV6_HASH_ADDRS, /* struct flow_dissector_key_addrs */
@@ -109,11 +119,16 @@ static inline bool skb_flow_dissect(const struct sk_buff *skb,
 }
 
 struct flow_keys {
-       struct flow_dissector_key_addrs addrs;
-       struct flow_dissector_key_ports ports;
+       struct flow_dissector_key_control control;
+#define FLOW_KEYS_HASH_START_FIELD basic
        struct flow_dissector_key_basic basic;
+       struct flow_dissector_key_ports ports;
+       struct flow_dissector_key_addrs addrs;
 };
 
+#define FLOW_KEYS_HASH_OFFSET          \
+       offsetof(struct flow_keys, FLOW_KEYS_HASH_START_FIELD)
+
 extern struct flow_dissector flow_keys_dissector;
 extern struct flow_dissector flow_keys_buf_dissector;
 

diff --git a/include/net/ip.h b/include/net/ip.h
index 9b976cf99122dfd6700efa8dff4eb6e796ea721a..16cfc87fed6c855a23be9b14efb3e64985dcae75 100644 (file)
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -360,6 +360,8 @@ static inline void inet_set_txhash(struct sock *sk)
        struct inet_sock *inet = inet_sk(sk);
        struct flow_keys keys;
 
+       memset(&keys, 0, sizeof(keys));
+
        keys.addrs.src = inet->inet_saddr;
        keys.addrs.dst = inet->inet_daddr;
        keys.ports.src = inet->inet_sport;

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 35d485c780802cc28dedb4f889f3478be712b9df..474ca466a0916c7f5debcaf9f7a042be1e388f4c 100644 (file)
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -699,6 +699,8 @@ static inline void ip6_set_txhash(struct sock *sk)
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct flow_keys keys;
 
+       memset(&keys, 0, sizeof(keys));
+
        keys.addrs.src = (__force __be32)ipv6_addr_hash(&np->saddr);
        keys.addrs.dst = (__force __be32)ipv6_addr_hash(&sk->sk_v6_daddr);
        keys.ports.src = inet->inet_sport;

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 0763795bea8f8c85ade60801979815cbaa678b9a..55b5f2962afacd6bb0cef5477d18b84ecdd38ee0 100644 (file)
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -57,9 +57,11 @@ void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
                flow_dissector->offset[key->key_id] = key->offset;
        }
 
-       /* Ensure that the dissector always includes basic key. That way
-        * we are able to avoid handling lack of it in fast path.
+       /* Ensure that the dissector always includes control and basic key.
+        * That way we are able to avoid handling lack of these in fast path.
         */
+       BUG_ON(!skb_flow_dissector_uses_key(flow_dissector,
+                                           FLOW_DISSECTOR_KEY_CONTROL));
        BUG_ON(!skb_flow_dissector_uses_key(flow_dissector,
                                            FLOW_DISSECTOR_KEY_BASIC));
 }
@@ -120,6 +122,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
                        void *target_container,
                        void *data, __be16 proto, int nhoff, int hlen)
 {
+       struct flow_dissector_key_control *key_control;
        struct flow_dissector_key_basic *key_basic;
        struct flow_dissector_key_addrs *key_addrs;
        struct flow_dissector_key_ports *key_ports;
@@ -132,6 +135,13 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
                hlen = skb_headlen(skb);
        }
 
+       /* It is ensured by skb_flow_dissector_init() that control key will
+        * be always present.
+        */
+       key_control = skb_flow_dissector_target(flow_dissector,
+                                               FLOW_DISSECTOR_KEY_CONTROL,
+                                               target_container);
+
        /* It is ensured by skb_flow_dissector_init() that basic key will
         * be always present.
         */
@@ -219,7 +229,7 @@ flow_label:
 
                        key_basic->n_proto = proto;
                        key_basic->ip_proto = ip_proto;
-                       key_basic->thoff = (u16)nhoff;
+                       key_control->thoff = (u16)nhoff;
 
                        if (skb_flow_dissector_uses_key(flow_dissector,
                                                        FLOW_DISSECTOR_KEY_PORTS)) {
@@ -275,7 +285,7 @@ flow_label:
                if (!hdr)
                        return false;
                key_basic->n_proto = proto;
-               key_basic->thoff = (u16)nhoff;
+               key_control->thoff = (u16)nhoff;
 
                if (skb_flow_dissector_uses_key(flow_dissector,
                                                FLOW_DISSECTOR_KEY_IPV6_HASH_ADDRS)) {
@@ -288,7 +298,7 @@ flow_label:
                return true;
        }
        case htons(ETH_P_FCOE):
-               key_basic->thoff = (u16)(nhoff + FCOE_HEADER_LEN);
+               key_control->thoff = (u16)(nhoff + FCOE_HEADER_LEN);
                /* fall through */
        default:
                return false;
@@ -345,7 +355,7 @@ flow_label:
 
        key_basic->n_proto = proto;
        key_basic->ip_proto = ip_proto;
-       key_basic->thoff = (u16) nhoff;
+       key_control->thoff = (u16)nhoff;
 
        if (skb_flow_dissector_uses_key(flow_dissector,
                                        FLOW_DISSECTOR_KEY_PORTS)) {
@@ -366,9 +376,21 @@ static __always_inline void __flow_hash_secret_init(void)
        net_get_random_once(&hashrnd, sizeof(hashrnd));
 }
 
-static __always_inline u32 __flow_hash_3words(u32 a, u32 b, u32 c, u32 keyval)
+static __always_inline u32 __flow_hash_words(u32 *words, u32 length, u32 keyval)
+{
+       return jhash2(words, length, keyval);
+}
+
+static inline void *flow_keys_hash_start(struct flow_keys *flow)
 {
-       return jhash_3words(a, b, c, keyval);
+       BUILD_BUG_ON(FLOW_KEYS_HASH_OFFSET % sizeof(u32));
+       return (void *)flow + FLOW_KEYS_HASH_OFFSET;
+}
+
+static inline size_t flow_keys_hash_length(struct flow_keys *flow)
+{
+       BUILD_BUG_ON((sizeof(*flow) - FLOW_KEYS_HASH_OFFSET) % sizeof(u32));
+       return (sizeof(*flow) - FLOW_KEYS_HASH_OFFSET) / sizeof(u32);
 }
 
 static inline u32 __flow_hash_from_keys(struct flow_keys *keys, u32 keyval)
@@ -383,10 +405,8 @@ static inline u32 __flow_hash_from_keys(struct flow_keys *keys, u32 keyval)
                swap(keys->ports.src, keys->ports.dst);
        }
 
-       hash = __flow_hash_3words((__force u32)keys->addrs.dst,
-                                 (__force u32)keys->addrs.src,
-                                 (__force u32)keys->ports.ports,
-                                 keyval);
+       hash = __flow_hash_words((u32 *)flow_keys_hash_start(keys),
+                                flow_keys_hash_length(keys), keyval);
        if (!hash)
                hash = 1;
 
@@ -473,7 +493,7 @@ EXPORT_SYMBOL(skb_get_hash_perturb);
 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
                   const struct flow_keys *keys, int hlen)
 {
-       u32 poff = keys->basic.thoff;
+       u32 poff = keys->control.thoff;
 
        switch (keys->basic.ip_proto) {
        case IPPROTO_TCP: {
@@ -536,6 +556,10 @@ u32 skb_get_poff(const struct sk_buff *skb)
 }
 
 static const struct flow_dissector_key flow_keys_dissector_keys[] = {
+       {
+               .key_id = FLOW_DISSECTOR_KEY_CONTROL,
+               .offset = offsetof(struct flow_keys, control),
+       },
        {
                .key_id = FLOW_DISSECTOR_KEY_BASIC,
                .offset = offsetof(struct flow_keys, basic),
@@ -555,6 +579,10 @@ static const struct flow_dissector_key flow_keys_dissector_keys[] = {
 };
 
 static const struct flow_dissector_key flow_keys_buf_dissector_keys[] = {
+       {
+               .key_id = FLOW_DISSECTOR_KEY_CONTROL,
+               .offset = offsetof(struct flow_keys, control),
+       },
        {
                .key_id = FLOW_DISSECTOR_KEY_BASIC,
                .offset = offsetof(struct flow_keys, basic),

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 8c8f34ef6980499bd8d333527f54b55b62c710a0..5a7d66c59684d67173fa4c720de225a3ae36a27f 100644 (file)
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -25,6 +25,7 @@
 
 struct fl_flow_key {
        int     indev_ifindex;
+       struct flow_dissector_key_control control;
        struct flow_dissector_key_basic basic;
        struct flow_dissector_key_eth_addrs eth;
        union {
@@ -347,6 +348,7 @@ static void fl_init_dissector(struct cls_fl_head *head,
        struct flow_dissector_key keys[FLOW_DISSECTOR_KEY_MAX];
        size_t cnt = 0;
 
+       FL_KEY_SET(keys, cnt, FLOW_DISSECTOR_KEY_CONTROL, control);
        FL_KEY_SET(keys, cnt, FLOW_DISSECTOR_KEY_BASIC, basic);
        FL_KEY_SET_IF_IN_RANGE(mask, keys, cnt,
                               FLOW_DISSECTOR_KEY_ETH_ADDRS, eth);