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Subject[PATCH 5/5] fs: remove ksys_dup()
Date
ksys_dup() is used only at one place in the kernel, namely to duplicate
fd 0 of /dev/console to stdout and stderr. The same functionality can be
achieved by using functions already available within the kernel namespace.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
---
fs/file.c | 7 +------
include/linux/syscalls.h | 1 -
init/main.c | 26 ++++++++++++++++++++------
3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/fs/file.c b/fs/file.c
index 3da91a112bab..2f4fcf985079 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -960,7 +960,7 @@ SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
return ksys_dup3(oldfd, newfd, 0);
}

-int ksys_dup(unsigned int fildes)
+SYSCALL_DEFINE1(dup, unsigned int, fildes)
{
int ret = -EBADF;
struct file *file = fget_raw(fildes);
@@ -975,11 +975,6 @@ int ksys_dup(unsigned int fildes)
return ret;
}

-SYSCALL_DEFINE1(dup, unsigned int, fildes)
-{
- return ksys_dup(fildes);
-}
-
int f_dupfd(unsigned int from, struct file *file, unsigned flags)
{
int err;
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 5262b7a76d39..2960dedcfde8 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1232,7 +1232,6 @@ asmlinkage long sys_ni_syscall(void);
*/

int ksys_umount(char __user *name, int flags);
-int ksys_dup(unsigned int fildes);
int ksys_chroot(const char __user *filename);
ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count);
int ksys_chdir(const char __user *filename);
diff --git a/init/main.c b/init/main.c
index 2cd736059416..ec3a1463ac69 100644
--- a/init/main.c
+++ b/init/main.c
@@ -93,6 +93,7 @@
#include <linux/rodata_test.h>
#include <linux/jump_label.h>
#include <linux/mem_encrypt.h>
+#include <linux/file.h>

#include <asm/io.h>
#include <asm/bugs.h>
@@ -1157,13 +1158,26 @@ static int __ref kernel_init(void *unused)

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;
+ unsigned int i;
+
+ /* Open /dev/console in kernelspace, this should never fail */
+ file = filp_open("/dev/console", O_RDWR, 0);
+ if (!file)
+ goto err_out;
+
+ /* create stdin/stdout/stderr, this should never fail */
+ for (i = 0; i < 3; i++) {
+ if (f_dupfd(i, file, 0) != i)
+ goto err_out;
+ }
+
+ return;

- /* create stdout/stderr */
- (void) ksys_dup(0);
- (void) ksys_dup(0);
+err_out:
+ /* no panic -- this might not be fatal */
+ pr_err("Warning: unable to open an initial console.\n");
+ return;
}

static noinline void __init kernel_init_freeable(void)
--
2.24.1
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