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authorDaniel Borkmann <daniel@iogearbox.net>2015-08-31 15:58:47 +0200
committerDavid S. Miller <davem@davemloft.net>2015-08-31 12:34:00 -0700
commitc3a8d9474684d391b0afc3970d9b249add15ec07 (patch)
treef12130b61955f4471ebd61474244ecf9ebdc0858 /net/ipv4/fib_semantics.c
parentb8d3e4163a3562d7cba486687904383e78e7dd6a (diff)
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/ipv4/fib_semantics.c')
-rw-r--r--net/ipv4/fib_semantics.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 115a08e70d43..992a9597daf8 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -879,6 +879,7 @@ static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
static int
fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
{
+ bool ecn_ca = false;
struct nlattr *nla;
int remaining;
@@ -898,7 +899,7 @@ fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
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)
return -EINVAL;
} else {
@@ -913,6 +914,9 @@ fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
fi->fib_metrics[type - 1] = val;
}
+ if (ecn_ca)
+ fi->fib_metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
+
return 0;
}