[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>

2 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index d98562f1df76..28a48279654d 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -426,6 +426,7 @@ enum
         NET_CIPSOV4_CACHE_BUCKET_SIZE=119,
         NET_CIPSOV4_RBM_OPTFMT=120,
         NET_CIPSOV4_RBM_STRICTVALID=121,
+        NET_TCP_AVAIL_CONG_CONTROL=122,
 };
 
 enum {
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 246916c2321e..6af4baf5b769 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -620,6 +620,9 @@ enum tcp_ca_event {
  * Interface for adding new TCP congestion control handlers
  */
 #define TCP_CA_NAME_MAX 16
+#define TCP_CA_MAX      128
+#define TCP_CA_BUF_MAX  (TCP_CA_NAME_MAX*TCP_CA_MAX)
+
 struct tcp_congestion_ops {
         struct list_head        list;
 
@@ -659,6 +662,7 @@ extern void tcp_init_congestion_control(struct sock *sk);
 extern void tcp_cleanup_congestion_control(struct sock *sk);
 extern int tcp_set_default_congestion_control(const char *name);
 extern void tcp_get_default_congestion_control(char *name);
+extern void tcp_get_available_congestion_control(char *buf, size_t len);
 extern int tcp_set_congestion_control(struct sock *sk, const char *name);
 extern void tcp_slow_start(struct tcp_sock *tp);