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>
diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index 614241b..2b10853 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -30,11 +30,7 @@
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 4cb47a1..106e02d 100644
--- a/init/main.c
+++ b/init/main.c
@@ -806,11 +806,6 @@
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 @@
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
