diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2010-03-02 23:53:19 -0800 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2010-03-03 14:56:07 -0500 |
| commit | 2bd3a997befc226ab4b504f05c5cbba305f3e0e6 (patch) | |
| tree | b510653236a8db16d6eaaf5b8b8c47000ee1b754 | |
| parent | 2329e392accdb1b277927e8d9cbf568ba3f3856d (diff) | |
init: Open /dev/console from rootfs
To avoid potential problems with an empty /dev open /dev/console
from rootfs instead of waiting to mount our root filesystem and
mounting it there. This effectively guarantees that there will
be a device node, and it won't be on a filesystem that we will
ever unmount, so there are no issues with leaving /dev/console
open and pinning the filesystem.
This is actually more effective than automatically mounting
devtmpfs on /dev because it removes removes the occasionally
problematic assumption that /dev/console exists from the boot
code.
With this patch I was able to throw busybox on my /boot partition
(which has no /dev directory) and boot into userspace without
problems.
The only possible negative consequence I can think of is that
someone out there deliberately used did not use a character device
that is major 5 minor 2 for /dev/console. Does anyone know of a
situation in which that could make sense?
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | init/do_mounts_initrd.c | 4 | ||||
| -rw-r--r-- | init/main.c | 11 |
2 files changed, 6 insertions, 9 deletions
diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c index 614241b5200..2b108538d0d 100644 --- a/init/do_mounts_initrd.c +++ b/init/do_mounts_initrd.c @@ -30,11 +30,7 @@ static int __init do_linuxrc(void * shell) extern char * envp_init[]; sys_close(old_fd);sys_close(root_fd); - sys_close(0);sys_close(1);sys_close(2); sys_setsid(); - (void) sys_open("/dev/console",O_RDWR,0); - (void) sys_dup(0); - (void) sys_dup(0); return kernel_execve(shell, argv, envp_init); } diff --git a/init/main.c b/init/main.c index 4cb47a159f0..106e02d7ffa 100644 --- a/init/main.c +++ b/init/main.c @@ -806,11 +806,6 @@ static noinline int init_post(void) system_state = SYSTEM_RUNNING; numa_default_policy(); - if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0) - printk(KERN_WARNING "Warning: unable to open an initial console.\n"); - - (void) sys_dup(0); - (void) sys_dup(0); current->signal->flags |= SIGNAL_UNKILLABLE; @@ -873,6 +868,12 @@ static int __init kernel_init(void * unused) do_basic_setup(); + /* Open the /dev/console on the rootfs, this should never fail */ + if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0) + printk(KERN_WARNING "Warning: unable to open an initial console.\n"); + + (void) sys_dup(0); + (void) sys_dup(0); /* * check if there is an early userspace init. If yes, let it do all * the work |