[TCP]: Allow choosing TCP congestion control via sockopt.

Allow using setsockopt to set TCP congestion control to use on a per
socket basis.

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

1 files changed, 30 insertions, 1 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f3dbc8dc1263..882436da9a3a 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1927,6 +1927,25 @@ int tcp_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
                 return tp->af_specific->setsockopt(sk, level, optname,
                                                    optval, optlen);
 
+        /* This is a string value all the others are int's */
+        if (optname == TCP_CONGESTION) {
+                char name[TCP_CA_NAME_MAX];
+
+                if (optlen < 1)
+                        return -EINVAL;
+
+                val = strncpy_from_user(name, optval,
+                                        min(TCP_CA_NAME_MAX-1, optlen));
+                if (val < 0)
+                        return -EFAULT;
+                name[val] = 0;
+
+                lock_sock(sk);
+                err = tcp_set_congestion_control(tp, name);
+                release_sock(sk);
+                return err;
+        }
+
         if (optlen < sizeof(int))
                 return -EINVAL;
 
@@ -2211,6 +2230,16 @@ int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
         case TCP_QUICKACK:
                 val = !tp->ack.pingpong;
                 break;
+
+        case TCP_CONGESTION:
+                if (get_user(len, optlen))
+                        return -EFAULT;
+                len = min_t(unsigned int, len, TCP_CA_NAME_MAX);
+                if (put_user(len, optlen))
+                        return -EFAULT;
+                if (copy_to_user(optval, tp->ca_ops->name, len))
+                        return -EFAULT;
+                return 0;
         default:
                 return -ENOPROTOOPT;
         };
@@ -2224,7 +2253,7 @@ int tcp_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
 
 
 extern void __skb_cb_too_small_for_tcp(int, int);
-extern void tcpdiag_init(void);
+extern struct tcp_congestion_ops tcp_reno;
 
 static __initdata unsigned long thash_entries;
 static int __init set_thash_entries(char *str)