Eric Lee / smarc-fsl-linux-kernel

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Commit 2bd3a997befc226ab4b504f05c5cbba305f3e0e6

Authored by Eric W. Biederman
Committed by Al Viro
1 parent 2329e392ac
Exists in master and in 39 other branches 8mp-imx_5.4.70_2.3.0, 8qm-imx_5.4.70_2.3.0, emb_imx_lf-5.15.y, emb_lf-6.1.y, imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, imx_4.1.15_1.0.0_ga, pitx_8mp_lf-5.10.y, rt-smarc-imx_4.1.15_1.0.0_ga, rt_linux_5.15.71, smarc-8m-android-11.0.0_2.0.0, smarc-imx6_4.14.98_2.0.0_ga, smarc-imx6_4.9.88_2.0.0_ga, smarc-imx7_4.14.98_2.0.0_ga, smarc-imx7_4.9.11_1.0.0_ga, smarc-imx7_4.9.88_2.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-imx_4.1.15_1.0.0_ga, smarc-imx_4.9.11_1.0.0_ga, smarc-imx_4.9.51_imx8m_ga, smarc-imx_4.9.88_2.0.0_ga, smarc-m6.0.1_2.1.0-ga, smarc-n7.1.2_2.0.0-ga, smarc-rel_imx_4.1.15_1.2.0_ga, smarc_8m_00d0_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.14.78_1.0.0_ga, smarc_8m_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.19.35_1.1.0, smarc_8mm_imx_4.14.78_1.0.0_ga, smarc_8mm_imx_4.14.98_2.0.0_ga, smarc_8mm_imx_4.19.35_1.1.0, smarc_8mm_imx_5.4.24_2.1.0, smarc_8mp_lf-5.10.y, smarc_8mq_imx_5.4.24_2.1.0, smarc_8mq_lf-5.10.y, smarc_imx_lf-5.15.y

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>

Showing 2 changed files with 6 additions and 9 deletions Side-by-side Diff

init/do_mounts_initrd.c
Diff comments   View file @ 2bd3a99
... ... @@ -30,11 +30,7 @@
30 30 extern char * envp_init[];
31 31  
32 32 sys_close(old_fd);sys_close(root_fd);
33   - sys_close(0);sys_close(1);sys_close(2);
34 33 sys_setsid();
35   - (void) sys_open("/dev/console",O_RDWR,0);
36   - (void) sys_dup(0);
37   - (void) sys_dup(0);
38 34 return kernel_execve(shell, argv, envp_init);
39 35 }
40 36  
... ... @@ -806,12 +806,7 @@
806 806 system_state = SYSTEM_RUNNING;
807 807 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");
811 809  
812   - (void) sys_dup(0);
813   - (void) sys_dup(0);
814   -
815 810 current->signal->flags |= SIGNAL_UNKILLABLE;
816 811  
817 812 if (ramdisk_execute_command) {
... ... @@ -873,6 +868,12 @@
873 868  
874 869 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 /*
877 878 * check if there is an early userspace init. If yes, let it do all
878 879 * the work