skbuff: store hash type in socket buffer...

...rather than a boolean merely indicating a canonical L4 hash.

skb_set_hash() takes a hash type (from enum pkt_hash_types) as an
argument but information is lost since only a single bit in the skb
stores whether that hash type is PKT_HASH_TYPE_L4 or not.

By using two bits it's possible to store the complete hash type
information for use by drivers, such as xen-netback when forwarding
network packets to VM frontend drivers.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jay Vosburgh <j.vosburgh@gmail.com>
Cc: Veaceslav Falico <vfalico@gmail.com>
Cc: Andy Gospodarek <gospo@cumulusnetworks.com>

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index d0f23cd6e236b0a51d3879ab8010537827d3424c..abf9c3ff20ee7635bd60143ccc72bd1e665bd93d 100644 (file)
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3137,7 +3137,7 @@ u32 bond_xmit_hash(struct bonding *bond, struct sk_buff *skb)
        u32 hash;
 
        if (bond->params.xmit_policy == BOND_XMIT_POLICY_ENCAP34 &&
-           skb->l4_hash)
+           skb_has_l4_hash(skb))
                return skb->hash;
 
        if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER2 ||

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4398411236f16c3f87691162909dc6197fb62b08..30e1e604283bc72c6b3c1a23dd64107cb58baa5f 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -506,8 +506,7 @@ static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1,
  *     @xmit_more: More SKBs are pending for this queue
  *     @ndisc_nodetype: router type (from link layer)
  *     @ooo_okay: allow the mapping of a socket to a queue to be changed
- *     @l4_hash: indicate hash is a canonical 4-tuple hash over transport
- *             ports.
+ *     @hash_type: indicates type of hash (see enum pkt_hash_types below)
  *     @sw_hash: indicates hash was computed in software stack
  *     @wifi_acked_valid: wifi_acked was set
  *     @wifi_acked: whether frame was acked on wifi or not
@@ -612,10 +611,10 @@ struct sk_buff {
        __u8                    nf_trace:1;
        __u8                    ip_summed:2;
        __u8                    ooo_okay:1;
-       __u8                    l4_hash:1;
        __u8                    sw_hash:1;
        __u8                    wifi_acked_valid:1;
        __u8                    wifi_acked:1;
+       /* 1 bit hole */
 
        __u8                    no_fcs:1;
        /* Indicates the inner headers are valid in the skbuff. */
@@ -632,7 +631,8 @@ struct sk_buff {
        __u8                    ipvs_property:1;
        __u8                    inner_protocol_type:1;
        __u8                    remcsum_offload:1;
-       /* 3 or 5 bit hole */
+       __u8                    hash_type:2;
+       /* 1 or 3 bit hole */
 
 #ifdef CONFIG_NET_SCHED
        __u16                   tc_index;       /* traffic control index */
@@ -941,19 +941,35 @@ static inline void skb_clear_hash(struct sk_buff *skb)
 {
        skb->hash = 0;
        skb->sw_hash = 0;
-       skb->l4_hash = 0;
+       skb->hash_type = 0;
+}
+
+static inline enum pkt_hash_types skb_hash_type(struct sk_buff *skb)
+{
+       return skb->hash_type;
+}
+
+static inline bool skb_has_l4_hash(struct sk_buff *skb)
+{
+       return skb_hash_type(skb) == PKT_HASH_TYPE_L4;
+}
+
+static inline bool skb_has_sw_hash(struct sk_buff *skb)
+{
+       return !!skb->sw_hash;
 }
 
 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
 {
-       if (!skb->l4_hash)
+       if (!skb_has_l4_hash(skb))
                skb_clear_hash(skb);
 }
 
 static inline void
-__skb_set_hash(struct sk_buff *skb, __u32 hash, bool is_sw, bool is_l4)
+__skb_set_hash(struct sk_buff *skb, __u32 hash, bool is_sw,
+              enum pkt_hash_types type)
 {
-       skb->l4_hash = is_l4;
+       skb->hash_type = type;
        skb->sw_hash = is_sw;
        skb->hash = hash;
 }
@@ -962,13 +978,13 @@ static inline void
 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
 {
        /* Used by drivers to set hash from HW */
-       __skb_set_hash(skb, hash, false, type == PKT_HASH_TYPE_L4);
+       __skb_set_hash(skb, hash, false, type);
 }
 
 static inline void
-__skb_set_sw_hash(struct sk_buff *skb, __u32 hash, bool is_l4)
+__skb_set_sw_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
 {
-       __skb_set_hash(skb, hash, true, is_l4);
+       __skb_set_hash(skb, hash, true, type);
 }
 
 void __skb_get_hash(struct sk_buff *skb);
@@ -1021,9 +1037,10 @@ static inline bool skb_flow_dissect_flow_keys_buf(struct flow_keys *flow,
                                  data, proto, nhoff, hlen, flags);
 }
 
+
 static inline __u32 skb_get_hash(struct sk_buff *skb)
 {
-       if (!skb->l4_hash && !skb->sw_hash)
+       if (!skb_has_l4_hash(skb) && !skb_has_sw_hash(skb))
                __skb_get_hash(skb);
 
        return skb->hash;
@@ -1033,11 +1050,12 @@ __u32 __skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6);
 
 static inline __u32 skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6)
 {
-       if (!skb->l4_hash && !skb->sw_hash) {
+       if (!skb_has_l4_hash(skb) && !skb_has_sw_hash(skb)) {
                struct flow_keys keys;
                __u32 hash = __get_hash_from_flowi6(fl6, &keys);
 
-               __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
+               __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys) ?
+                                 PKT_HASH_TYPE_L4 : PKT_HASH_TYPE_L3);
        }
 
        return skb->hash;
@@ -1047,11 +1065,12 @@ __u32 __skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl);
 
 static inline __u32 skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl4)
 {
-       if (!skb->l4_hash && !skb->sw_hash) {
+       if (!skb_has_l4_hash(skb) && !skb_has_sw_hash(skb)) {
                struct flow_keys keys;
                __u32 hash = __get_hash_from_flowi4(fl4, &keys);
 
-               __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
+               __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys) ?
+                                 PKT_HASH_TYPE_L4 : PKT_HASH_TYPE_L3);
        }
 
        return skb->hash;
@@ -1068,7 +1087,7 @@ static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
 {
        to->hash = from->hash;
        to->sw_hash = from->sw_hash;
-       to->l4_hash = from->l4_hash;
+       to->hash_type = from->hash_type;
 };
 
 static inline void skb_sender_cpu_clear(struct sk_buff *skb)

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 8c8548cf5888c4535a809494fad454e755ff6749..418b8c5cbf1b1fbdb00a8419cce96aec7cc0ca4b 100644 (file)
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -182,6 +182,11 @@ static inline bool flow_keys_have_l4(struct flow_keys *keys)
        return (keys->ports.ports || keys->tags.flow_label);
 }
 
+static inline bool flow_keys_have_l3(struct flow_keys *keys)
+{
+       return !!keys->control.addr_type;
+}
+
 u32 flow_hash_from_keys(struct flow_keys *keys);
 
 #endif

diff --git a/include/net/sock.h b/include/net/sock.h
index 64a75458d22cc2fc4e972601972cf9ff9cf0a57a..b9f68dbca37f07e5faf584134a584c615c1dcf3c 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1938,7 +1938,7 @@ static inline void sock_poll_wait(struct file *filp,
 static inline void skb_set_hash_from_sk(struct sk_buff *skb, struct sock *sk)
 {
        if (sk->sk_txhash) {
-               skb->l4_hash = 1;
+               skb->hash_type = PKT_HASH_TYPE_L4;
                skb->hash = sk->sk_txhash;
        }
 }

diff --git a/include/trace/events/net.h b/include/trace/events/net.h
index 49cc7c3de25221f2e014c80f12189bb1edc3b946..25e79794d641e9232363b4ec188025b64b50ff60 100644 (file)
--- a/include/trace/events/net.h
+++ b/include/trace/events/net.h
@@ -180,7 +180,7 @@ DECLARE_EVENT_CLASS(net_dev_rx_verbose_template,
                __entry->protocol = ntohs(skb->protocol);
                __entry->ip_summed = skb->ip_summed;
                __entry->hash = skb->hash;
-               __entry->l4_hash = skb->l4_hash;
+               __entry->l4_hash = skb->hash_type == PKT_HASH_TYPE_L4;
                __entry->len = skb->len;
                __entry->data_len = skb->data_len;
                __entry->truesize = skb->truesize;

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index d79699c9d1b9eb9f250254e360b2d5a7b4ff6e34..956208b03a8dbac3130234d0577bfcebde8bada1 100644 (file)
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -658,17 +658,30 @@ EXPORT_SYMBOL(make_flow_keys_digest);
  *
  * This function calculates a flow hash based on src/dst addresses
  * and src/dst port numbers.  Sets hash in skb to non-zero hash value
- * on success, zero indicates no valid hash.  Also, sets l4_hash in skb
- * if hash is a canonical 4-tuple hash over transport ports.
+ * on success, zero indicates no valid hash in which case the hash type
+ * is set to NONE. If the hash is a canonical 4-tuple hash over transport
+ * ports then type is set to L4. If the hash did not include transport
+ * then type is set to L3, otherwise it is assumed to be L2 only.
  */
 void __skb_get_hash(struct sk_buff *skb)
 {
        struct flow_keys keys;
+       u32 hash;
+       enum pkt_hash_types type;
 
        __flow_hash_secret_init();
 
-       __skb_set_sw_hash(skb, ___skb_get_hash(skb, &keys, hashrnd),
-                         flow_keys_have_l4(&keys));
+       hash = ___skb_get_hash(skb, &keys, hashrnd);
+       if (hash == 0)
+               type = PKT_HASH_TYPE_NONE;
+       else if (flow_keys_have_l4(&keys))
+               type = PKT_HASH_TYPE_L4;
+       else if (flow_keys_have_l3(&keys))
+               type = PKT_HASH_TYPE_L3;
+       else
+               type = PKT_HASH_TYPE_L2;
+
+       __skb_set_sw_hash(skb, hash, type);
 }
 EXPORT_SYMBOL(__skb_get_hash);
 
@@ -698,7 +711,8 @@ __u32 __skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6)
        keys.basic.ip_proto = fl6->flowi6_proto;
 
        __skb_set_sw_hash(skb, flow_hash_from_keys(&keys),
-                         flow_keys_have_l4(&keys));
+                         flow_keys_have_l4(&keys) ?
+                         PKT_HASH_TYPE_L4 : PKT_HASH_TYPE_L3);
 
        return skb->hash;
 }
@@ -719,7 +733,8 @@ __u32 __skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl4)
        keys.basic.ip_proto = fl4->flowi4_proto;
 
        __skb_set_sw_hash(skb, flow_hash_from_keys(&keys),
-                         flow_keys_have_l4(&keys));
+                         flow_keys_have_l4(&keys) ?
+                         PKT_HASH_TYPE_L4 : PKT_HASH_TYPE_L3);
 
        return skb->hash;
 }