From: Eric Dumazet <edumazet@google.com>
Date: Tue, 28 Apr 2015 23:23:49 +0000 (-0700)
Subject: tcp: add TCP_CC_INFO socket option
X-Git-Tag: omap-for-v4.2/wakeirq-drivers~2^2~30^2~34^2~19
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6e9250f59ef9efb932c84850cd221f22c2a03c4a;p=pandora-kernel.git

tcp: add TCP_CC_INFO socket option

Some Congestion Control modules can provide per flow information,
but current way to get this information is to use netlink.

Like TCP_INFO, let's add TCP_CC_INFO so that applications can
issue a getsockopt() if they have a socket file descriptor,
instead of playing complex netlink games.

Sample usage would be :

  union tcp_cc_info info;
  socklen_t len = sizeof(info);

  if (getsockopt(fd, SOL_TCP, TCP_CC_INFO, &info, &len) == -1)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index a48f93f3207b..faa72f4fa547 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -112,6 +112,7 @@ enum {
 #define TCP_FASTOPEN		23	/* Enable FastOpen on listeners */
 #define TCP_TIMESTAMP		24
 #define TCP_NOTSENT_LOWAT	25	/* limit number of unsent bytes in write queue */
+#define TCP_CC_INFO		26	/* Get Congestion Control (optional) info */
 
 struct tcp_repair_opt {
 	__u32	opt_code;
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