net: bpfilter: fallback to netfilter if failed to load bpfilter kernel module

If bpfilter is not available return ENOPROTOOPT to fallback to netfilter.

Function request_module() returns both errors and userspace exit codes.
Just ignore them. Rechecking bpfilter_ops is enough.

Fixes: d2ba09c17a ("net: add skeleton of bpfilter kernel module")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/bpfilter/sockopt.c

@@ -30,13 +30,11 @@ static int bpfilter_mbox_request(struct sock *sk, int optname,
 	mutex_lock(&bpfilter_ops.lock);
 	if (!bpfilter_ops.sockopt) {
 		mutex_unlock(&bpfilter_ops.lock);
-		err = request_module("bpfilter");
+		request_module("bpfilter");
 		mutex_lock(&bpfilter_ops.lock);
 
-		if (err)
-			goto out;
 		if (!bpfilter_ops.sockopt) {
-			err = -ECHILD;
+			err = -ENOPROTOOPT;
 			goto out;
 		}
 	}