don't bother with kernel_thread/kernel_execve for launching linuxrc

exec_usermodehelper_fns() will do just fine...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 16 insertions, 25 deletions

diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index 135959a276be..5e4ded51788e 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -16,13 +16,13 @@
 #include <linux/initrd.h>
 #include <linux/sched.h>
 #include <linux/freezer.h>
+#include <linux/kmod.h>
 
 #include "do_mounts.h"
 
 unsigned long initrd_start, initrd_end;
 int initrd_below_start_ok;
 unsigned int real_root_dev;     /* do_proc_dointvec cannot handle kdev_t */
-static int __initdata old_fd, root_fd;
 static int __initdata mount_initrd = 1;
 
 static int __init no_initrd(char *str)
@@ -33,33 +33,29 @@ static int __init no_initrd(char *str)
 
 __setup("noinitrd", no_initrd);
 
-static int __init do_linuxrc(void *_shell)
+static int init_linuxrc(struct subprocess_info *info, struct cred *new)
 {
-        static const char *argv[] = { "linuxrc", NULL, };
-        extern const char *envp_init[];
-        const char *shell = _shell;
-
-        sys_close(old_fd);sys_close(root_fd);
+        sys_unshare(CLONE_FS | CLONE_FILES);
+        /* move initrd over / and chdir/chroot in initrd root */
+        sys_chdir("/root");
+        sys_mount(".", "/", NULL, MS_MOVE, NULL);
+        sys_chroot(".");
         sys_setsid();
-        return kernel_execve(shell, argv, envp_init);
+        return 0;
 }
 
 static void __init handle_initrd(void)
 {
+        static char *argv[] = { "linuxrc", NULL, };
+        extern char *envp_init[];
         int error;
-        int pid;
 
         real_root_dev = new_encode_dev(ROOT_DEV);
         create_dev("/dev/root.old", Root_RAM0);
         /* mount initrd on rootfs' /root */
         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
         sys_mkdir("/old", 0700);
-        root_fd = sys_open("/", 0, 0);
-        old_fd = sys_open("/old", 0, 0);
-        /* move initrd over / and chdir/chroot in initrd root */
-        sys_chdir("/root");
-        sys_mount(".", "/", NULL, MS_MOVE, NULL);
-        sys_chroot(".");
+        sys_chdir("/old");
 
         /*
          * In case that a resume from disk is carried out by linuxrc or one of
@@ -67,27 +63,22 @@ static void __init handle_initrd(void)
          */
         current->flags |= PF_FREEZER_SKIP;
 
-        pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
-        if (pid > 0)
-                while (pid != sys_wait4(-1, NULL, 0, NULL))
-                        yield();
+        call_usermodehelper_fns("/linuxrc", argv, envp_init, UMH_WAIT_PROC,
+                        init_linuxrc, NULL, NULL);
 
         current->flags &= ~PF_FREEZER_SKIP;
 
         /* move initrd to rootfs' /old */
-        sys_fchdir(old_fd);
-        sys_mount("/", ".", NULL, MS_MOVE, NULL);
+        sys_mount("..", ".", NULL, MS_MOVE, NULL);
         /* switch root and cwd back to / of rootfs */
-        sys_fchdir(root_fd);
-        sys_chroot(".");
-        sys_close(old_fd);
-        sys_close(root_fd);
+        sys_chroot("..");
 
         if (new_decode_dev(real_root_dev) == Root_RAM0) {
                 sys_chdir("/old");
                 return;
         }
 
+        sys_chdir("/");
         ROOT_DEV = new_decode_dev(real_root_dev);
         mount_root();