From ba4df2808a86f8b103c4db0b8807649383e9bd13 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 2 Oct 2012 15:29:10 -0400 Subject: don't bother with kernel_thread/kernel_execve for launching linuxrc exec_usermodehelper_fns() will do just fine... Signed-off-by: Al Viro --- init/do_mounts_initrd.c | 41 ++++++++++++++++------------------------- 1 file changed, 16 insertions(+), 25 deletions(-) (limited to 'init') diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c index 135959a276b..5e4ded51788 100644 --- a/init/do_mounts_initrd.c +++ b/init/do_mounts_initrd.c @@ -16,13 +16,13 @@ #include #include #include +#include #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(); -- cgit v1.2.3 From d6b2123802d2b7eee8c62cd0ebd73e8636cbb068 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 10 Oct 2012 19:57:26 -0400 Subject: make sure that we always have a return path from kernel_execve() The only place where kernel_execve() is called without a way to return to the caller of kernel_thread() callback is kernel_post(). Reorganize kernel_init()/kernel_post() - instead of the former calling the latter in the end (and getting freed by it), have the latter *begin* with calling the former (and turn the latter into kernel_thread() callback, of course). Signed-off-by: Al Viro --- init/main.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) (limited to 'init') diff --git a/init/main.c b/init/main.c index b28673087ac..a490ffecb7b 100644 --- a/init/main.c +++ b/init/main.c @@ -794,11 +794,11 @@ static void run_init_process(const char *init_filename) 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(); @@ -835,7 +835,7 @@ static noinline int init_post(void) "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. @@ -890,7 +890,4 @@ 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; } -- cgit v1.2.3 From a74fb73c12398b250fdc5e333a11e15a9e3a84fc Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 10 Oct 2012 21:28:25 -0400 Subject: infrastructure for saner ret_from_kernel_thread semantics * allow kernel_execve() leave the actual return to userland to caller (selected by CONFIG_GENERIC_KERNEL_EXECVE). Callers updated accordingly. * architecture that does select GENERIC_KERNEL_EXECVE in its Kconfig should have its ret_from_kernel_thread() do this: call schedule_tail call the callback left for it by copy_thread(); if it ever returns, that's because it has just done successful kernel_execve() jump to return from syscall IOW, its only difference from ret_from_fork() is that it does call the callback. * such an architecture should also get rid of ret_from_kernel_execve() and __ARCH_WANT_KERNEL_EXECVE This is the last part of infrastructure patches in that area - from that point on work on different architectures can live independently. Signed-off-by: Al Viro --- init/main.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) (limited to 'init') diff --git a/init/main.c b/init/main.c index a490ffecb7b..02df2ddc5f8 100644 --- a/init/main.c +++ b/init/main.c @@ -69,6 +69,7 @@ #include #include #include +#include #include #include @@ -788,10 +789,10 @@ 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); } static void __init kernel_init_freeable(void); @@ -810,7 +811,8 @@ static int __ref kernel_init(void *unused) 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); } @@ -822,14 +824,16 @@ static int __ref kernel_init(void *unused) * 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."); -- cgit v1.2.3