[PATCH 18/23] init: open code setting up stdin/stdout/stderr

Christoph Hellwig
2020-07-14T19:10:03Z

Don't rely on the implicit set_fs(KERNEL_DS) for ksys_open to work, but
instead open a struct file for /dev/console and then install it as FD
0/1/2 manually.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
init/main.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/init/main.c b/init/main.c
index 0ead83e86b5aa2..db0621dfbb0468 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1457,15 +1457,19 @@ static int __ref kernel_init(void *unused)
"See Linux Documentation/admin-guide/init.rst for guidance.");
}

+/* Open /dev/console, for stdin/stdout/stderr, this should never fail */
void console_on_rootfs(void)
{
- /* Open the /dev/console as stdin, this should never fail */
- if (ksys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
- pr_err("Warning: unable to open an initial console.\n");
+ struct file *file = filp_open("/dev/console", O_RDWR, 0);

- /* create stdout/stderr */
- (void) ksys_dup(0);
- (void) ksys_dup(0);
+ if (IS_ERR(file)) {
+ pr_err("Warning: unable to open an initial console.\n");
+ return;
+ }
+ get_file_rcu_many(file, 2);
+ fd_install(get_unused_fd_flags(0), file);
+ fd_install(get_unused_fd_flags(0), file);
+ fd_install(get_unused_fd_flags(0), file);
}

static noinline void __init kernel_init_freeable(void)
--
2.27.0