Re: [PATCH net] ipv6: omit traffic class when calculating flow hash
From: David Ahern <hidden>
Date: 2018-06-01 16:42:16
Also in:
lkml
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
On 6/1/18 4:34 AM, Michal Kubecek wrote:
quoted hunk ↗ jump to hunk
Some of the code paths calculating flow hash for IPv6 use flowlabel member of struct flowi6 which, despite its name, encodes both flow label and traffic class. If traffic class changes within a TCP connection (as e.g. ssh does), ECMP route can switch between path. It's also incosistent with other code paths where ip6_flowlabel() (returning only flow label) is used to feed the key. Use only flow label everywhere, including one place where hash key is set using ip6_flowinfo(). Fixes: 51ebd3181572 ("ipv6: add support of equal cost multipath (ECMP)") Fixes: f70ea018da06 ("net: Add functions to get skb->hash based on flow structures") Signed-off-by: Michal Kubecek <redacted> --- net/core/flow_dissector.c | 3 ++- net/ipv6/route.c | 5 +++-- 2 files changed, 5 insertions(+), 3 deletions(-)diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index d29f09bc5ff9..441d3db76e8e 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c@@ -1334,7 +1334,8 @@ __u32 __get_hash_from_flowi6(const struct flowi6 *fl6, struct flow_keys *keys) keys->ports.src = fl6->fl6_sport; keys->ports.dst = fl6->fl6_dport; keys->keyid.keyid = fl6->fl6_gre_key; - keys->tags.flow_label = (__force u32)fl6->flowlabel; + keys->tags.flow_label = (__force u32)(fl6->flowlabel & + IPV6_FLOWLABEL_MASK); keys->basic.ip_proto = fl6->flowi6_proto; return flow_hash_from_keys(keys);diff --git a/net/ipv6/route.c b/net/ipv6/route.c index f4d61736c41a..fcbacf1677f8 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c@@ -1868,7 +1868,7 @@ static void ip6_multipath_l3_keys(const struct sk_buff *skb, } else { keys->addrs.v6addrs.src = key_iph->saddr; keys->addrs.v6addrs.dst = key_iph->daddr; - keys->tags.flow_label = ip6_flowinfo(key_iph); + keys->tags.flow_label = ip6_flowlabel(key_iph); keys->basic.ip_proto = key_iph->nexthdr; } }@@ -1889,7 +1889,8 @@ u32 rt6_multipath_hash(const struct net *net, const struct flowi6 *fl6, } else { hash_keys.addrs.v6addrs.src = fl6->saddr; hash_keys.addrs.v6addrs.dst = fl6->daddr; - hash_keys.tags.flow_label = (__force u32)fl6->flowlabel; + hash_keys.tags.flow_label = (__force u32)(fl6->flowlabel & + IPV6_FLOWLABEL_MASK); hash_keys.basic.ip_proto = fl6->flowi6_proto; } break;
Can you make an inline for the flowlabel conversion. Something like this:
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 798558fd1681..e36eca2f8531 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h@@ -284,6 +284,11 @@ struct ip6_flowlabel { #define IPV6_FLOWLABEL_MASK cpu_to_be32(0x000FFFFF) #define IPV6_FLOWLABEL_STATELESS_FLAG cpu_to_be32(0x00080000) +static inline u32 flowi6_get_flowlabel(const struct flowi6 *fl6) +{ + return (__force u32)(fl6->flowlabel & IPV6_FLOWLABEL_MASK); +} + #define IPV6_TCLASS_MASK (IPV6_FLOWINFO_MASK & ~IPV6_FLOWLABEL_MASK) #define IPV6_TCLASS_SHIFT 20
From there we can fix the flow struct to have flowinfo instead of
flowlabel and use the macro to hide the conversion.