diff mbox series

[RFC,net-next,07/10] ipv6: Add custom multipath hash policy

Message ID 20210502162257.3472453-8-idosch@idosch.org (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series Add support for custom multipath hash | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 4 maintainers not CCed: yoshfuji@linux-ipv6.org linux-doc@vger.kernel.org dsahern@kernel.org corbet@lwn.net
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch warning WARNING: line length of 83 exceeds 80 columns
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/header_inline success Link

Commit Message

Ido Schimmel May 2, 2021, 4:22 p.m. UTC 
From: Ido Schimmel <idosch@nvidia.com>

Add a new multipath hash policy where the packet fields used for hash
calculation are determined by user space via the
fib_multipath_hash_fields sysctl that was introduced in the previous
patch.

The current set of available packet fields includes both outer and inner
fields, which requires two invocations of the flow dissector. Avoid
unnecessary dissection of the outer or inner flows by skipping
dissection if the 'need_outer' or 'need_inner' variables are not set.
These fields are set / cleared as part of the control path when the
fib_multipath_hash_fields sysctl is configured.

In accordance with the existing policies, when an skb is not available,
packet fields are extracted from the provided flow key. In which case,
only outer fields are considered.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
---
 Documentation/networking/ip-sysctl.rst |   2 +
 net/ipv6/route.c                       | 125 +++++++++++++++++++++++++
 net/ipv6/sysctl_net_ipv6.c             |   3 +-
 3 files changed, 129 insertions(+), 1 deletion(-)

Comments

David Ahern May 4, 2021, 2:46 a.m. UTC | #1 
On 5/2/21 10:22 AM, Ido Schimmel wrote:
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 9935e18146e5..b4c65c5baf35 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -2326,6 +2326,125 @@ static void ip6_multipath_l3_keys(const struct sk_buff *skb,
>  	}
>  }
>  
> +static u32 rt6_multipath_custom_hash_outer(const struct net *net,
> +					   const struct sk_buff *skb,
> +					   bool *p_has_inner)
> +{
> +	unsigned long *hash_fields = ip6_multipath_hash_fields(net);
> +	struct flow_keys keys, hash_keys;
> +
> +	if (!net->ipv6.sysctl.multipath_hash_fields_need_outer)
> +		return 0;
> +
> +	memset(&hash_keys, 0, sizeof(hash_keys));
> +	skb_flow_dissect_flow_keys(skb, &keys, FLOW_DISSECTOR_F_STOP_AT_ENCAP);
> +
> +	hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_IP, hash_fields))
> +		hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_IP, hash_fields))
> +		hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(IP_PROTO, hash_fields))
> +		hash_keys.basic.ip_proto = keys.basic.ip_proto;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(FLOWLABEL, hash_fields))
> +		hash_keys.tags.flow_label = keys.tags.flow_label;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_PORT, hash_fields))
> +		hash_keys.ports.src = keys.ports.src;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_PORT, hash_fields))
> +		hash_keys.ports.dst = keys.ports.dst;
> +
> +	*p_has_inner = !!(keys.control.flags & FLOW_DIS_ENCAPSULATION);
> +	return flow_hash_from_keys(&hash_keys);
> +}
> +
> +static u32 rt6_multipath_custom_hash_inner(const struct net *net,
> +					   const struct sk_buff *skb,
> +					   bool has_inner)
> +{
> +	unsigned long *hash_fields = ip6_multipath_hash_fields(net);
> +	struct flow_keys keys, hash_keys;
> +
> +	/* We assume the packet carries an encapsulation, but if none was
> +	 * encountered during dissection of the outer flow, then there is no
> +	 * point in calling the flow dissector again.
> +	 */
> +	if (!has_inner)
> +		return 0;
> +
> +	if (!net->ipv6.sysctl.multipath_hash_fields_need_inner)
> +		return 0;
> +
> +	memset(&hash_keys, 0, sizeof(hash_keys));
> +	skb_flow_dissect_flow_keys(skb, &keys, 0);
> +
> +	if (!(keys.control.flags & FLOW_DIS_ENCAPSULATION))
> +		return 0;
> +
> +	if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV4_ADDRS) {
> +		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
> +		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_SRC_IP, hash_fields))
> +			hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
> +		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_DST_IP, hash_fields))
> +			hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
> +	} else if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV6_ADDRS) {
> +		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
> +		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_SRC_IP, hash_fields))
> +			hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
> +		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_DST_IP, hash_fields))
> +			hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
> +		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_FLOWLABEL, hash_fields))
> +			hash_keys.tags.flow_label = keys.tags.flow_label;
> +	}
> +
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_IP_PROTO, hash_fields))
> +		hash_keys.basic.ip_proto = keys.basic.ip_proto;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_SRC_PORT, hash_fields))
> +		hash_keys.ports.src = keys.ports.src;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_DST_PORT, hash_fields))
> +		hash_keys.ports.dst = keys.ports.dst;
> +
> +	return flow_hash_from_keys(&hash_keys);
> +}
> +
> +static u32 rt6_multipath_custom_hash_skb(const struct net *net,
> +					 const struct sk_buff *skb)
> +{
> +	u32 mhash, mhash_inner;
> +	bool has_inner = true;
> +
> +	mhash = rt6_multipath_custom_hash_outer(net, skb, &has_inner);
> +	mhash_inner = rt6_multipath_custom_hash_inner(net, skb, has_inner);
> +
> +	return jhash_2words(mhash, mhash_inner, 0);
> +}
> +
> +static u32 rt6_multipath_custom_hash_fl6(const struct net *net,
> +					 const struct flowi6 *fl6)
> +{
> +	unsigned long *hash_fields = ip6_multipath_hash_fields(net);
> +	struct flow_keys hash_keys;
> +
> +	if (!net->ipv6.sysctl.multipath_hash_fields_need_outer)
> +		return 0;
> +
> +	memset(&hash_keys, 0, sizeof(hash_keys));
> +	hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_IP, hash_fields))
> +		hash_keys.addrs.v6addrs.src = fl6->saddr;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_IP, hash_fields))
> +		hash_keys.addrs.v6addrs.dst = fl6->daddr;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(IP_PROTO, hash_fields))
> +		hash_keys.basic.ip_proto = fl6->flowi6_proto;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(FLOWLABEL, hash_fields))
> +		hash_keys.tags.flow_label = (__force u32)flowi6_get_flowlabel(fl6);
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_PORT, hash_fields))
> +		hash_keys.ports.src = fl6->fl6_sport;
> +	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_PORT, hash_fields))
> +		hash_keys.ports.dst = fl6->fl6_dport;
> +
> +	return flow_hash_from_keys(&hash_keys);
> +}
> +

given the amount of duplication with IPv4, should be able to use inline
macros and the flowi_uli union to make some common helpers without
impacting performance.
Ido Schimmel May 5, 2021, 8:50 a.m. UTC | #2 
On Mon, May 03, 2021 at 08:46:18PM -0600, David Ahern wrote:
> On 5/2/21 10:22 AM, Ido Schimmel wrote:
> > diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> > index 9935e18146e5..b4c65c5baf35 100644
> > --- a/net/ipv6/route.c
> > +++ b/net/ipv6/route.c
> > @@ -2326,6 +2326,125 @@ static void ip6_multipath_l3_keys(const struct sk_buff *skb,
> >  	}
> >  }
> >  
> > +static u32 rt6_multipath_custom_hash_outer(const struct net *net,
> > +					   const struct sk_buff *skb,
> > +					   bool *p_has_inner)
> > +{
> > +	unsigned long *hash_fields = ip6_multipath_hash_fields(net);
> > +	struct flow_keys keys, hash_keys;
> > +
> > +	if (!net->ipv6.sysctl.multipath_hash_fields_need_outer)
> > +		return 0;
> > +
> > +	memset(&hash_keys, 0, sizeof(hash_keys));
> > +	skb_flow_dissect_flow_keys(skb, &keys, FLOW_DISSECTOR_F_STOP_AT_ENCAP);
> > +
> > +	hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_IP, hash_fields))
> > +		hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_IP, hash_fields))
> > +		hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(IP_PROTO, hash_fields))
> > +		hash_keys.basic.ip_proto = keys.basic.ip_proto;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(FLOWLABEL, hash_fields))
> > +		hash_keys.tags.flow_label = keys.tags.flow_label;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_PORT, hash_fields))
> > +		hash_keys.ports.src = keys.ports.src;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_PORT, hash_fields))
> > +		hash_keys.ports.dst = keys.ports.dst;
> > +
> > +	*p_has_inner = !!(keys.control.flags & FLOW_DIS_ENCAPSULATION);
> > +	return flow_hash_from_keys(&hash_keys);
> > +}
> > +
> > +static u32 rt6_multipath_custom_hash_inner(const struct net *net,
> > +					   const struct sk_buff *skb,
> > +					   bool has_inner)
> > +{
> > +	unsigned long *hash_fields = ip6_multipath_hash_fields(net);
> > +	struct flow_keys keys, hash_keys;
> > +
> > +	/* We assume the packet carries an encapsulation, but if none was
> > +	 * encountered during dissection of the outer flow, then there is no
> > +	 * point in calling the flow dissector again.
> > +	 */
> > +	if (!has_inner)
> > +		return 0;
> > +
> > +	if (!net->ipv6.sysctl.multipath_hash_fields_need_inner)
> > +		return 0;
> > +
> > +	memset(&hash_keys, 0, sizeof(hash_keys));
> > +	skb_flow_dissect_flow_keys(skb, &keys, 0);
> > +
> > +	if (!(keys.control.flags & FLOW_DIS_ENCAPSULATION))
> > +		return 0;
> > +
> > +	if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV4_ADDRS) {
> > +		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
> > +		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_SRC_IP, hash_fields))
> > +			hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
> > +		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_DST_IP, hash_fields))
> > +			hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
> > +	} else if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV6_ADDRS) {
> > +		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
> > +		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_SRC_IP, hash_fields))
> > +			hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
> > +		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_DST_IP, hash_fields))
> > +			hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
> > +		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_FLOWLABEL, hash_fields))
> > +			hash_keys.tags.flow_label = keys.tags.flow_label;
> > +	}
> > +
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_IP_PROTO, hash_fields))
> > +		hash_keys.basic.ip_proto = keys.basic.ip_proto;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_SRC_PORT, hash_fields))
> > +		hash_keys.ports.src = keys.ports.src;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_DST_PORT, hash_fields))
> > +		hash_keys.ports.dst = keys.ports.dst;
> > +
> > +	return flow_hash_from_keys(&hash_keys);
> > +}
> > +
> > +static u32 rt6_multipath_custom_hash_skb(const struct net *net,
> > +					 const struct sk_buff *skb)
> > +{
> > +	u32 mhash, mhash_inner;
> > +	bool has_inner = true;
> > +
> > +	mhash = rt6_multipath_custom_hash_outer(net, skb, &has_inner);
> > +	mhash_inner = rt6_multipath_custom_hash_inner(net, skb, has_inner);
> > +
> > +	return jhash_2words(mhash, mhash_inner, 0);
> > +}
> > +
> > +static u32 rt6_multipath_custom_hash_fl6(const struct net *net,
> > +					 const struct flowi6 *fl6)
> > +{
> > +	unsigned long *hash_fields = ip6_multipath_hash_fields(net);
> > +	struct flow_keys hash_keys;
> > +
> > +	if (!net->ipv6.sysctl.multipath_hash_fields_need_outer)
> > +		return 0;
> > +
> > +	memset(&hash_keys, 0, sizeof(hash_keys));
> > +	hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_IP, hash_fields))
> > +		hash_keys.addrs.v6addrs.src = fl6->saddr;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_IP, hash_fields))
> > +		hash_keys.addrs.v6addrs.dst = fl6->daddr;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(IP_PROTO, hash_fields))
> > +		hash_keys.basic.ip_proto = fl6->flowi6_proto;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(FLOWLABEL, hash_fields))
> > +		hash_keys.tags.flow_label = (__force u32)flowi6_get_flowlabel(fl6);
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_PORT, hash_fields))
> > +		hash_keys.ports.src = fl6->fl6_sport;
> > +	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_PORT, hash_fields))
> > +		hash_keys.ports.dst = fl6->fl6_dport;
> > +
> > +	return flow_hash_from_keys(&hash_keys);
> > +}
> > +
> 
> given the amount of duplication with IPv4, should be able to use inline
> macros and the flowi_uli union to make some common helpers without
> impacting performance.

OK, will try to create some common helpers
diff mbox series

Patch

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 5289336227b3..8b88499fe555 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -1774,6 +1774,8 @@  fib_multipath_hash_policy - INTEGER
 	- 0 - Layer 3 (source and destination addresses plus flow label)
 	- 1 - Layer 4 (standard 5-tuple)
 	- 2 - Layer 3 or inner Layer 3 if present
+	- 3 - Custom multipath hash. Fields used for multipath hash calculation
+	  are determined by fib_multipath_hash_fields sysctl
 
 fib_multipath_hash_fields - list of comma separated ranges
 	When fib_multipath_hash_policy is set to 3 (custom multipath hash), the
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 9935e18146e5..b4c65c5baf35 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2326,6 +2326,125 @@  static void ip6_multipath_l3_keys(const struct sk_buff *skb,
 	}
 }
 
+static u32 rt6_multipath_custom_hash_outer(const struct net *net,
+					   const struct sk_buff *skb,
+					   bool *p_has_inner)
+{
+	unsigned long *hash_fields = ip6_multipath_hash_fields(net);
+	struct flow_keys keys, hash_keys;
+
+	if (!net->ipv6.sysctl.multipath_hash_fields_need_outer)
+		return 0;
+
+	memset(&hash_keys, 0, sizeof(hash_keys));
+	skb_flow_dissect_flow_keys(skb, &keys, FLOW_DISSECTOR_F_STOP_AT_ENCAP);
+
+	hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_IP, hash_fields))
+		hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_IP, hash_fields))
+		hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(IP_PROTO, hash_fields))
+		hash_keys.basic.ip_proto = keys.basic.ip_proto;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(FLOWLABEL, hash_fields))
+		hash_keys.tags.flow_label = keys.tags.flow_label;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_PORT, hash_fields))
+		hash_keys.ports.src = keys.ports.src;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_PORT, hash_fields))
+		hash_keys.ports.dst = keys.ports.dst;
+
+	*p_has_inner = !!(keys.control.flags & FLOW_DIS_ENCAPSULATION);
+	return flow_hash_from_keys(&hash_keys);
+}
+
+static u32 rt6_multipath_custom_hash_inner(const struct net *net,
+					   const struct sk_buff *skb,
+					   bool has_inner)
+{
+	unsigned long *hash_fields = ip6_multipath_hash_fields(net);
+	struct flow_keys keys, hash_keys;
+
+	/* We assume the packet carries an encapsulation, but if none was
+	 * encountered during dissection of the outer flow, then there is no
+	 * point in calling the flow dissector again.
+	 */
+	if (!has_inner)
+		return 0;
+
+	if (!net->ipv6.sysctl.multipath_hash_fields_need_inner)
+		return 0;
+
+	memset(&hash_keys, 0, sizeof(hash_keys));
+	skb_flow_dissect_flow_keys(skb, &keys, 0);
+
+	if (!(keys.control.flags & FLOW_DIS_ENCAPSULATION))
+		return 0;
+
+	if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV4_ADDRS) {
+		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
+		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_SRC_IP, hash_fields))
+			hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
+		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_DST_IP, hash_fields))
+			hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
+	} else if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV6_ADDRS) {
+		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
+		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_SRC_IP, hash_fields))
+			hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
+		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_DST_IP, hash_fields))
+			hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
+		if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_FLOWLABEL, hash_fields))
+			hash_keys.tags.flow_label = keys.tags.flow_label;
+	}
+
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_IP_PROTO, hash_fields))
+		hash_keys.basic.ip_proto = keys.basic.ip_proto;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_SRC_PORT, hash_fields))
+		hash_keys.ports.src = keys.ports.src;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(INNER_DST_PORT, hash_fields))
+		hash_keys.ports.dst = keys.ports.dst;
+
+	return flow_hash_from_keys(&hash_keys);
+}
+
+static u32 rt6_multipath_custom_hash_skb(const struct net *net,
+					 const struct sk_buff *skb)
+{
+	u32 mhash, mhash_inner;
+	bool has_inner = true;
+
+	mhash = rt6_multipath_custom_hash_outer(net, skb, &has_inner);
+	mhash_inner = rt6_multipath_custom_hash_inner(net, skb, has_inner);
+
+	return jhash_2words(mhash, mhash_inner, 0);
+}
+
+static u32 rt6_multipath_custom_hash_fl6(const struct net *net,
+					 const struct flowi6 *fl6)
+{
+	unsigned long *hash_fields = ip6_multipath_hash_fields(net);
+	struct flow_keys hash_keys;
+
+	if (!net->ipv6.sysctl.multipath_hash_fields_need_outer)
+		return 0;
+
+	memset(&hash_keys, 0, sizeof(hash_keys));
+	hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_IP, hash_fields))
+		hash_keys.addrs.v6addrs.src = fl6->saddr;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_IP, hash_fields))
+		hash_keys.addrs.v6addrs.dst = fl6->daddr;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(IP_PROTO, hash_fields))
+		hash_keys.basic.ip_proto = fl6->flowi6_proto;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(FLOWLABEL, hash_fields))
+		hash_keys.tags.flow_label = (__force u32)flowi6_get_flowlabel(fl6);
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(SRC_PORT, hash_fields))
+		hash_keys.ports.src = fl6->fl6_sport;
+	if (FIB_MULTIPATH_HASH_TEST_FIELD(DST_PORT, hash_fields))
+		hash_keys.ports.dst = fl6->fl6_dport;
+
+	return flow_hash_from_keys(&hash_keys);
+}
+
 /* if skb is set it will be used and fl6 can be NULL */
 u32 rt6_multipath_hash(const struct net *net, const struct flowi6 *fl6,
 		       const struct sk_buff *skb, struct flow_keys *flkeys)
@@ -2416,6 +2535,12 @@  u32 rt6_multipath_hash(const struct net *net, const struct flowi6 *fl6,
 		}
 		mhash = flow_hash_from_keys(&hash_keys);
 		break;
+	case 3:
+		if (skb)
+			mhash = rt6_multipath_custom_hash_skb(net, skb);
+		else
+			mhash = rt6_multipath_custom_hash_fl6(net, fl6);
+		break;
 	}
 
 	return mhash >> 1;
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index 8d94a1d621d0..38d444b1bb60 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -23,6 +23,7 @@ 
 #endif
 
 static int two = 2;
+static int three = 3;
 static int flowlabel_reflect_max = 0x7;
 static int auto_flowlabels_max = IP6_AUTO_FLOW_LABEL_MAX;
 
@@ -174,7 +175,7 @@  static struct ctl_table ipv6_table_template[] = {
 		.mode		= 0644,
 		.proc_handler   = proc_rt6_multipath_hash_policy,
 		.extra1		= SYSCTL_ZERO,
-		.extra2		= &two,
+		.extra2		= &three,
 	},
 	{
 		.procname	= "fib_multipath_hash_fields",