[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>
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 665394a..4970d10 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -21,7 +21,7 @@
{
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 @@
{
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 @@
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 @@
.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);