diff options
| author | Daniel Borkmann <daniel@iogearbox.net> | 2015-08-31 16:58:47 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-08-31 22:34:00 +0300 |
| commit | c3a8d9474684d391b0afc3970d9b249add15ec07 (patch) | |
| tree | f12130b61955f4471ebd61474244ecf9ebdc0858 /net/ipv6 | |
| parent | b8d3e4163a3562d7cba486687904383e78e7dd6a (diff) | |
| download | linux-c3a8d9474684d391b0afc3970d9b249add15ec07.tar.xz | |
tcp: use dctcp if enabled on the route to the initiator
Currently, the following case doesn't use DCTCP, even if it should:
A responder has f.e. Cubic as system wide default, but for a specific
route to the initiating host, DCTCP is being set in RTAX_CC_ALGO. The
initiating host then uses DCTCP as congestion control, but since the
initiator sets ECT(0), tcp_ecn_create_request() doesn't set ecn_ok,
and we have to fall back to Reno after 3WHS completes.
We were thinking on how to solve this in a minimal, non-intrusive
way without bloating tcp_ecn_create_request() needlessly: lets cache
the CA ecn option flag in RTAX_FEATURES. In other words, when ECT(0)
is set on the SYN packet, set ecn_ok=1 iff route RTAX_FEATURES
contains the unexposed (internal-only) DST_FEATURE_ECN_CA. This allows
to only do a single metric feature lookup inside tcp_ecn_create_request().
Joint work with Florian Westphal.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/route.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 8771530df45e..f45cac6f8356 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1698,6 +1698,7 @@ out: static int ip6_convert_metrics(struct mx6_config *mxc, const struct fib6_config *cfg) { + bool ecn_ca = false; struct nlattr *nla; int remaining; u32 *mp; @@ -1722,7 +1723,7 @@ static int ip6_convert_metrics(struct mx6_config *mxc, char tmp[TCP_CA_NAME_MAX]; nla_strlcpy(tmp, nla, sizeof(tmp)); - val = tcp_ca_get_key_by_name(tmp); + val = tcp_ca_get_key_by_name(tmp, &ecn_ca); if (val == TCP_CA_UNSPEC) goto err; } else { @@ -1735,8 +1736,12 @@ static int ip6_convert_metrics(struct mx6_config *mxc, __set_bit(type - 1, mxc->mx_valid); } - mxc->mx = mp; + if (ecn_ca) { + __set_bit(RTAX_FEATURES - 1, mxc->mx_valid); + mp[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA; + } + mxc->mx = mp; return 0; err: kfree(mp); |