[TCP]: Add tcp_available_congestion_control sysctl.

Create /proc/sys/net/ipv4/tcp_available_congestion_control
that reflects currently available TCP choices.

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

1 files changed, 16 insertions, 0 deletions

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 1e2982f4acd4..d846d7b95e1f 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -139,6 +139,22 @@ static int __init tcp_congestion_default(void)
 late_initcall(tcp_congestion_default);
 
 
+/* Build string with list of available congestion control values */
+void tcp_get_available_congestion_control(char *buf, size_t maxlen)
+{
+        struct tcp_congestion_ops *ca;
+        size_t offs = 0;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
+                offs += snprintf(buf + offs, maxlen - offs,
+                                 "%s%s",
+                                 offs == 0 ? "" : " ", ca->name);
+
+        }
+        rcu_read_unlock();
+}
+
 /* Get current default congestion control */
 void tcp_get_default_congestion_control(char *name)
 {