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devtmpfs: use do_mount() instead of ksys_mount() 

In devtmpfs, do_mount() can be called directly instead of complex wrapping
by ksys_mount():
- the first and third arguments are const strings in the kernel,
  and do not need to be copied over from userspace;
- the fifth argument is NULL, and therefore no page needs to be
  copied over from userspace;
- the second and fourth argument are passed through anyway.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
This commit is contained in:
Dominik Brodowski 2018-10-23 22:10:35 +02:00
parent ae4b064e2a
commit 5e787dbf65
3 changed files with 6 additions and 6 deletions
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6
drivers/base/devtmpfs.c
View File

@ -359,7 +359,7 @@ static int handle_remove(const char *nodename, struct device *dev)
* If configured, or requested by the commandline, devtmpfs will be
* auto-mounted after the kernel mounted the root filesystem.
*/
int devtmpfs_mount(const char *mntdir)
int devtmpfs_mount(void)
{
int err;
@ -369,7 +369,7 @@ int devtmpfs_mount(const char *mntdir)
if (!thread)
return 0;
err = ksys_mount("devtmpfs", mntdir, "devtmpfs", MS_SILENT, NULL);
err = do_mount("devtmpfs", "dev", "devtmpfs", MS_SILENT, NULL);
if (err)
printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
else
@ -394,7 +394,7 @@ static int devtmpfsd(void *p)
*err = ksys_unshare(CLONE_NEWNS);
if (*err)
goto out;
*err = ksys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
*err = do_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
if (*err)
goto out;
ksys_chdir("/.."); /* will traverse into overmounted root */

4
include/linux/device.h
View File

@ -1666,11 +1666,11 @@ extern bool kill_device(struct device *dev);
#ifdef CONFIG_DEVTMPFS
extern int devtmpfs_create_node(struct device *dev);
extern int devtmpfs_delete_node(struct device *dev);
extern int devtmpfs_mount(const char *mntdir);
extern int devtmpfs_mount(void);
#else
static inline int devtmpfs_create_node(struct device *dev) { return 0; }
static inline int devtmpfs_delete_node(struct device *dev) { return 0; }
static inline int devtmpfs_mount(const char *mountpoint) { return 0; }
static inline int devtmpfs_mount(void) { return 0; }
#endif
/* drivers/base/power/shutdown.c */

2
init/do_mounts.c
View File

@ -670,7 +670,7 @@ void __init prepare_namespace(void)
mount_root();
out:
devtmpfs_mount("dev");
devtmpfs_mount();
ksys_mount(".", "/", NULL, MS_MOVE, NULL);
ksys_chroot(".");
}