Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal

Pull third pile of kernel_execve() patches from Al Viro:
 "The last bits of infrastructure for kernel_thread() et.al., with
  alpha/arm/x86 use of those.  Plus sanitizing the asm glue and
  do_notify_resume() on alpha, fixing the "disabled irq while running
  task_work stuff" breakage there.

  At that point the rest of kernel_thread/kernel_execve/sys_execve work
  can be done independently for different architectures.  The only
  pending bits that do depend on having all architectures converted are
  restrictred to fs/* and kernel/* - that'll obviously have to wait for
  the next cycle.

  I thought we'd have to wait for all of them done before we start
  eliminating the longjump-style insanity in kernel_execve(), but it
  turned out there's a very simple way to do that without flagday-style
  changes."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal:
  alpha: switch to saner kernel_execve() semantics
  arm: switch to saner kernel_execve() semantics
  x86, um: convert to saner kernel_execve() semantics
  infrastructure for saner ret_from_kernel_thread semantics
  make sure that kernel_thread() callbacks call do_exit() themselves
  make sure that we always have a return path from kernel_execve()
  ppc: eeh_event should just use kthread_run()
  don't bother with kernel_thread/kernel_execve for launching linuxrc
  alpha: get rid of switch_stack argument of do_work_pending()
  alpha: don't bother passing switch_stack separately from regs
  alpha: take SIGPENDING/NOTIFY_RESUME loop into signal.c
  alpha: simplify TIF_NEED_RESCHED handling

2 files changed, 33 insertions, 41 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();
 
diff --git a/init/main.c b/init/main.c
index 313360fe1118..9cf77ab138a6 100644
--- a/init/main.c
+++ b/init/main.c
@@ -69,6 +69,7 @@
 #include <linux/slab.h>
 #include <linux/perf_event.h>
 #include <linux/file.h>
+#include <linux/ptrace.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -791,17 +792,17 @@ static void __init do_pre_smp_initcalls(void)
 		do_one_initcall(*fn);
 }
 
-static void run_init_process(const char *init_filename)
+static int run_init_process(const char *init_filename)
 {
 	argv_init[0] = init_filename;
-	kernel_execve(init_filename, argv_init, envp_init);
+	return kernel_execve(init_filename, argv_init, envp_init);
 }
 
-/* This is a non __init function. Force it to be noinline otherwise gcc
- * makes it inline to init() and it becomes part of init.text section
- */
-static noinline int init_post(void)
+static void __init kernel_init_freeable(void);
+
+static int __ref kernel_init(void *unused)
 {
+	kernel_init_freeable();
 	/* need to finish all async __init code before freeing the memory */
 	async_synchronize_full();
 	free_initmem();
@@ -813,7 +814,8 @@ static noinline int init_post(void)
 	flush_delayed_fput();
 
 	if (ramdisk_execute_command) {
-		run_init_process(ramdisk_execute_command);
+		if (!run_init_process(ramdisk_execute_command))
+			return 0;
 		printk(KERN_WARNING "Failed to execute %s\n",
 				ramdisk_execute_command);
 	}
@@ -825,20 +827,22 @@ static noinline int init_post(void)
 	 * trying to recover a really broken machine.
 	 */
 	if (execute_command) {
-		run_init_process(execute_command);
+		if (!run_init_process(execute_command))
+			return 0;
 		printk(KERN_WARNING "Failed to execute %s.  Attempting "
 					"defaults...\n", execute_command);
 	}
-	run_init_process("/sbin/init");
-	run_init_process("/etc/init");
-	run_init_process("/bin/init");
-	run_init_process("/bin/sh");
+	if (!run_init_process("/sbin/init") ||
+	    !run_init_process("/etc/init") ||
+	    !run_init_process("/bin/init") ||
+	    !run_init_process("/bin/sh"))
+		return 0;
 
 	panic("No init found.  Try passing init= option to kernel. "
 	      "See Linux Documentation/init.txt for guidance.");
 }
 
-static int __init kernel_init(void * unused)
+static void __init kernel_init_freeable(void)
 {
 	/*
 	 * Wait until kthreadd is all set-up.
@@ -893,7 +897,4 @@ static int __init kernel_init(void * unused)
 	 * we're essentially up and running. Get rid of the
 	 * initmem segments and start the user-mode stuff..
 	 */
-
-	init_post();
-	return 0;
 }