nbd-server: do not call fcntl F_SETFL unnecessarily

Call fcntl F_SETFL only when new file status flags differ from the old one.

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>

diff --git a/nbd-server.c b/nbd-server.c
index cd8fdb92f1d788b00de927eee5dc3a5e46836ae9..3e64c37f9373639404ff024d87a3feb357d30ecb 100644 (file)
--- a/nbd-server.c
+++ b/nbd-server.c
@@ -2165,7 +2165,8 @@ void destroy_pid_t(gpointer data) {
 static void
 handle_connection(GArray *servers, int net, SERVER *serve, CLIENT *client)
 {
-       int sock_flags;
+       int sock_flags_old;
+       int sock_flags_new;
 
        if(serve->max_connections > 0 &&
           g_hash_table_size(children) >= serve->max_connections) {
@@ -2173,10 +2174,12 @@ handle_connection(GArray *servers, int net, SERVER *serve, CLIENT *client)
                close(net);
                return;
        }
-       if((sock_flags = fcntl(net, F_GETFL, 0))==-1) {
+       if((sock_flags_old = fcntl(net, F_GETFL, 0)) == -1) {
                err("fcntl F_GETFL");
        }
-       if(fcntl(net, F_SETFL, sock_flags &~O_NONBLOCK)==-1) {
+       sock_flags_new = sock_flags_old & ~O_NONBLOCK;
+       if (sock_flags_new != sock_flags_old &&
+           fcntl(net, F_SETFL, sock_flags_new) == -1) {
                err("fcntl F_SETFL ~O_NONBLOCK");
        }
        if(!client) {