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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 /include/net
parentb8d3e4163a3562d7cba486687904383e78e7dd6a (diff)
downloadop-kernel-dev-c3a8d9474684d391b0afc3970d9b249add15ec07.zip
op-kernel-dev-c3a8d9474684d391b0afc3970d9b249add15ec07.tar.gz
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 'include/net')
-rw-r--r--include/net/dst.h6
-rw-r--r--include/net/tcp.h2
2 files changed, 7 insertions, 1 deletions
diff --git a/include/net/dst.h b/include/net/dst.h
index 4c48016..9261d92 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -207,6 +207,12 @@ static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
p[metric-1] = val;
}
+/* Kernel-internal feature bits that are unallocated in user space. */
+#define DST_FEATURE_ECN_CA (1 << 31)
+
+#define DST_FEATURE_MASK (DST_FEATURE_ECN_CA)
+#define DST_FEATURE_ECN_MASK (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
+
static inline u32
dst_feature(const struct dst_entry *dst, u32 feature)
{
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 4a7b039..0cab28c 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -888,7 +888,7 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
extern struct tcp_congestion_ops tcp_reno;
struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
-u32 tcp_ca_get_key_by_name(const char *name);
+u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca);
#ifdef CONFIG_INET
char *tcp_ca_get_name_by_key(u32 key, char *buffer);
#else
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