diff options
author | Eric W. Biederman <ebiederm@xmission.com> | 2010-03-03 02:53:19 -0500 |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2010-03-03 14:56:07 -0500 |
commit | 2bd3a997befc226ab4b504f05c5cbba305f3e0e6 (patch) | |
tree | b510653236a8db16d6eaaf5b8b8c47000ee1b754 /init | |
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>
Diffstat (limited to 'init')
-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 614241b5200c..2b108538d0d9 100644 --- a/init/do_mounts_initrd.c +++ b/init/do_mounts_initrd.c | |||
@@ -30,11 +30,7 @@ static int __init do_linuxrc(void * shell) | |||
30 | extern char * envp_init[]; | 30 | extern char * envp_init[]; |
31 | 31 | ||
32 | sys_close(old_fd);sys_close(root_fd); | 32 | sys_close(old_fd);sys_close(root_fd); |
33 | sys_close(0);sys_close(1);sys_close(2); | ||
34 | sys_setsid(); | 33 | sys_setsid(); |
35 | (void) sys_open("/dev/console",O_RDWR,0); | ||
36 | (void) sys_dup(0); | ||
37 | (void) sys_dup(0); | ||
38 | return kernel_execve(shell, argv, envp_init); | 34 | return kernel_execve(shell, argv, envp_init); |
39 | } | 35 | } |
40 | 36 | ||
diff --git a/init/main.c b/init/main.c index 4cb47a159f02..106e02d7ffa5 100644 --- a/init/main.c +++ b/init/main.c | |||
@@ -806,11 +806,6 @@ static noinline int init_post(void) | |||
806 | system_state = SYSTEM_RUNNING; | 806 | system_state = SYSTEM_RUNNING; |
807 | numa_default_policy(); | 807 | numa_default_policy(); |
808 | 808 | ||
809 | if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0) | ||
810 | printk(KERN_WARNING "Warning: unable to open an initial console.\n"); | ||
811 | |||
812 | (void) sys_dup(0); | ||
813 | (void) sys_dup(0); | ||
814 | 809 | ||
815 | current->signal->flags |= SIGNAL_UNKILLABLE; | 810 | current->signal->flags |= SIGNAL_UNKILLABLE; |
816 | 811 | ||
@@ -873,6 +868,12 @@ static int __init kernel_init(void * unused) | |||
873 | 868 | ||
874 | do_basic_setup(); | 869 | do_basic_setup(); |
875 | 870 | ||
871 | /* Open the /dev/console on the rootfs, this should never fail */ | ||
872 | if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0) | ||
873 | printk(KERN_WARNING "Warning: unable to open an initial console.\n"); | ||
874 | |||
875 | (void) sys_dup(0); | ||
876 | (void) sys_dup(0); | ||
876 | /* | 877 | /* |
877 | * check if there is an early userspace init. If yes, let it do all | 878 | * check if there is an early userspace init. If yes, let it do all |
878 | * the work | 879 | * the work |