[TCP]: Allow choosing TCP congestion control via sockopt.
[linux-2.6.git] / net / ipv4 / tcp_cong.c
index 665394a..4970d10 100644 (file)
@@ -21,7 +21,7 @@ static struct tcp_congestion_ops *tcp_ca_find(const char *name)
 {
        struct tcp_congestion_ops *e;
 
-       list_for_each_entry(e, &tcp_cong_list, list) {
+       list_for_each_entry_rcu(e, &tcp_cong_list, list) {
                if (strcmp(e->name, name) == 0)
                        return e;
        }
@@ -77,6 +77,9 @@ void tcp_init_congestion_control(struct tcp_sock *tp)
 {
        struct tcp_congestion_ops *ca;
 
+       if (tp->ca_ops != &tcp_init_congestion_ops)
+               return;
+
        rcu_read_lock();
        list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
                if (try_module_get(ca->owner)) {
@@ -139,6 +142,34 @@ void tcp_get_default_congestion_control(char *name)
        rcu_read_unlock();
 }
 
+/* Change congestion control for socket */
+int tcp_set_congestion_control(struct tcp_sock *tp, const char *name)
+{
+       struct tcp_congestion_ops *ca;
+       int err = 0;
+
+       rcu_read_lock();
+       ca = tcp_ca_find(name);
+       if (ca == tp->ca_ops)
+               goto out;
+
+       if (!ca)
+               err = -ENOENT;
+
+       else if (!try_module_get(ca->owner))
+               err = -EBUSY;
+
+       else {
+               tcp_cleanup_congestion_control(tp);
+               tp->ca_ops = ca;
+               if (tp->ca_ops->init)
+                       tp->ca_ops->init(tp);
+       }
+ out:
+       rcu_read_unlock();
+       return err;
+}
+
 /*
  * TCP Reno congestion control
  * This is special case used for fallback as well.
@@ -192,4 +223,15 @@ struct tcp_congestion_ops tcp_reno = {
        .min_cwnd       = tcp_reno_min_cwnd,
 };
 
-EXPORT_SYMBOL_GPL(tcp_reno);
+/* Initial congestion control used (until SYN)
+ * really reno under another name so we can tell difference
+ * during tcp_set_default_congestion_control
+ */
+struct tcp_congestion_ops tcp_init_congestion_ops  = {
+       .name           = "",
+       .owner          = THIS_MODULE,
+       .ssthresh       = tcp_reno_ssthresh,
+       .cong_avoid     = tcp_reno_cong_avoid,
+       .min_cwnd       = tcp_reno_min_cwnd,
+};
+EXPORT_SYMBOL_GPL(tcp_init_congestion_ops);