From: Stephen Hemminger <shemminger@osdl.org>
Date: Fri, 10 Nov 2006 00:36:36 +0000 (-0800)
Subject: [TCP]: Allow autoloading of congestion control via setsockopt.
X-Git-Tag: v3.12-rc1~31383^2~47^2~519
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=35bfbc94070e480f350c868abc4ff9f77e7f2051;p=kernel%2Fkernel-generic.git

[TCP]: Allow autoloading of congestion control via setsockopt.

If user has permision to load modules, then autoload then attempt
autoload of TCP congestion module.

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 343d619..5ca7723 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -113,7 +113,7 @@ int tcp_set_default_congestion_control(const char *name)
 	spin_lock(&tcp_cong_list_lock);
 	ca = tcp_ca_find(name);
 #ifdef CONFIG_KMOD
-	if (!ca) {
+	if (!ca && capable(CAP_SYS_MODULE)) {
 		spin_unlock(&tcp_cong_list_lock);
 
 		request_module("tcp_%s", name);
@@ -236,9 +236,19 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
 
 	rcu_read_lock();
 	ca = tcp_ca_find(name);
+	/* no change asking for existing value */
 	if (ca == icsk->icsk_ca_ops)
 		goto out;
 
+#ifdef CONFIG_KMOD
+	/* not found attempt to autoload module */
+	if (!ca && capable(CAP_SYS_MODULE)) {
+		rcu_read_unlock();
+		request_module("tcp_%s", name);
+		rcu_read_lock();
+		ca = tcp_ca_find(name);
+	}
+#endif
 	if (!ca)
 		err = -ENOENT;