mdev: move daemon setup to dedicated function

Signed-off-by: Jan Klötzke <jan@kloetzke.net>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 27 insertions, 17 deletions

diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index 8b06d3456..4c00a2d7e 100644
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -1165,6 +1165,29 @@ static void initial_scan(char *temp)
 # define KERN_RCVBUF (128 * 1024 * 1024)
 # define MAX_ENV 32
 
+static int daemon_init(char *temp)
+{
+        int fd;
+
+        /* Subscribe for UEVENT kernel messages */
+        /* Without a sufficiently big RCVBUF, a ton of simultaneous events
+         * can trigger ENOBUFS on read, which is unrecoverable.
+         * Reproducer:
+         *      mdev -d
+         *      find /sys -name uevent -exec sh -c 'echo add >"{}"' ';'
+         */
+        fd = create_and_bind_to_netlink(NETLINK_KOBJECT_UEVENT, 1 << 0, KERN_RCVBUF);
+
+        /*
+         * Make inital scan after the uevent socket is alive and
+         * _before_ we fork away. Already open mdev.log because we work
+         * in daemon mode.
+         */
+        initial_scan(temp);
+
+        return fd;
+}
+
 static void daemon_loop(char *temp, int fd)
 {
         for (;;) {
@@ -1234,24 +1257,11 @@ int mdev_main(int argc UNUSED_PARAM, char **argv)
 #if ENABLE_FEATURE_MDEV_DAEMON
         if (opt & MDEV_OPT_DAEMON) {
                 /*
-                 * Daemon mode listening on uevent netlink socket.
-                 */
-                int fd;
-
-                /* Subscribe for UEVENT kernel messages */
-                /* Without a sufficiently big RCVBUF, a ton of simultaneous events
-                 * can trigger ENOBUFS on read, which is unrecoverable.
-                 * Reproducer:
-                 *      mdev -d
-                 *      find /sys -name uevent -exec sh -c 'echo add >"{}"' ';'
-                 */
-                fd = create_and_bind_to_netlink(NETLINK_KOBJECT_UEVENT, 1 << 0, KERN_RCVBUF);
-
-                /*
-                 * Make inital scan after the uevent socket is alive and
-                 * _before_ we fork away.
+                 * Daemon mode listening on uevent netlink socket. Fork away
+                 * after initial scan so that caller can be sure everything
+                 * is up-to-date when mdev process returns.
                  */
-                initial_scan(temp);
+                int fd = daemon_init(temp);
 
                 if (!(opt & MDEV_OPT_FOREGROUND))
                         bb_daemonize_or_rexec(0, argv);