[TCP]: Report congestion control algorithm in tcp_diag.

Enhancement to the tcp_diag interface used by the iproute2 ss command
to report the tcp congestion control being used by a socket.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 7 insertions, 2 deletions

diff --git a/include/linux/tcp_diag.h b/include/linux/tcp_diag.h
index ceee962e1d15..7a5996743946 100644
--- a/include/linux/tcp_diag.h
+++ b/include/linux/tcp_diag.h
@@ -99,9 +99,10 @@ enum
         TCPDIAG_MEMINFO,
         TCPDIAG_INFO,
         TCPDIAG_VEGASINFO,
+        TCPDIAG_CONG,
 };
 
-#define TCPDIAG_MAX TCPDIAG_VEGASINFO
+#define TCPDIAG_MAX TCPDIAG_CONG
 
 
 /* TCPDIAG_MEM */
@@ -123,5 +124,4 @@ struct tcpvegas_info {
         __u32   tcpv_minrtt;
 };
 
-
 #endif /* _TCP_DIAG_H_ */
diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
index a4e512036d88..f66945cb158f 100644
--- a/net/ipv4/tcp_diag.c
+++ b/net/ipv4/tcp_diag.c
@@ -65,6 +65,11 @@ static int tcpdiag_fill(struct sk_buff *skb, struct sock *sk,
                 if (ext & (1<<(TCPDIAG_INFO-1)))
                         info = TCPDIAG_PUT(skb, TCPDIAG_INFO, sizeof(*info));
                 
+                if (ext & (1<<(TCPDIAG_CONG-1))) {
+                        size_t len = strlen(tp->ca_ops->name);
+                        strcpy(TCPDIAG_PUT(skb, TCPDIAG_CONG, len+1),
+                               tp->ca_ops->name);
+                }
         }
         r->tcpdiag_family = sk->sk_family;
         r->tcpdiag_state = sk->sk_state;