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Date:	Wed, 17 Feb 2016 09:01:25 +0000
From:	Paul Durrant <Paul.Durrant@...rix.com>
To:	Paul Durrant <Paul.Durrant@...rix.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:	"David S. Miller" <davem@...emloft.net>,
	Jay Vosburgh <j.vosburgh@...il.com>,
	Veaceslav Falico <vfalico@...il.com>,
	Andy Gospodarek <gospo@...ulusnetworks.com>
Subject: RE: [PATCH net-next] store complete hash type information in socket
 buffer...

Ping?

> -----Original Message-----
> From: Paul Durrant [mailto:paul.durrant@...rix.com]
> Sent: 15 February 2016 08:32
> To: netdev@...r.kernel.org
> Cc: Paul Durrant; David S. Miller; Jay Vosburgh; Veaceslav Falico; Andy
> Gospodarek
> Subject: [PATCH net-next] store complete hash type information 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.
> 
> Signed-off-by: Paul Durrant <paul.durrant@...rix.com>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Jay Vosburgh <j.vosburgh@...il.com>
> Cc: Veaceslav Falico <vfalico@...il.com>
> Cc: Andy Gospodarek <gospo@...ulusnetworks.com>
> ---
>  drivers/net/bonding/bond_main.c |  2 +-
>  include/linux/skbuff.h          | 53 ++++++++++++++++++++++++++++----------
> ---
>  include/net/flow_dissector.h    |  5 ++++
>  include/net/sock.h              |  2 +-
>  include/trace/events/net.h      |  2 +-
>  net/core/flow_dissector.c       | 27 ++++++++++++++++-----
>  6 files changed, 65 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/net/bonding/bond_main.c
> b/drivers/net/bonding/bond_main.c
> index 45bdd87..ad0ee00 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -3173,7 +3173,7 @@ 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 3920675..b991ca2 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -595,8 +595,7 @@ static inline bool skb_mstamp_after(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
> @@ -701,10 +700,10 @@ 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. */
> @@ -721,7 +720,8 @@ 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 */
> @@ -1030,19 +1030,35 @@ 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;
>  }
> @@ -1051,13 +1067,13 @@ 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);
> @@ -1110,9 +1126,10 @@ 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;
> @@ -1122,11 +1139,12 @@ __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;
> @@ -1136,11 +1154,12 @@ __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;
> @@ -1157,7 +1176,7 @@ 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 8c8548c..418b8c5 100644
> --- 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 255d3e0..21b8cdc 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -1828,7 +1828,7 @@ 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 49cc7c3..25e7979 100644
> --- 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 d79699c..956208b 100644
> --- 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;
>  }
> --
> 2.1.4

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