Using this wrapper allows us to avoid the in-kernel calls to the sys_unlink() syscall. The ksys_ prefix denotes that this function is meant s a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_unlink().
In the near future, all callers of ksys_unlink() should be converted to call do_unlinkat() directly or, at least, to operate on regular kernel pointers. This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.ga17...@light.dominikbrodowski.net Cc: Al Viro <v...@zeniv.linux.org.uk> Cc: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Dominik Brodowski <li...@dominikbrodowski.net> --- include/linux/syscalls.h | 11 +++++++++++ init/do_mounts.h | 2 +- init/do_mounts_initrd.c | 4 ++-- init/do_mounts_rd.c | 2 +- init/initramfs.c | 4 ++-- 5 files changed, 17 insertions(+), 6 deletions(-) diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 090645b48447..7cbfb41e666b 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -954,4 +954,15 @@ 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); +/* + * The following kernel syscall equivalents are just wrappers to fs-internal + * functions. Therefore, provide stubs to be inlined at the callsites. + */ +extern long do_unlinkat(int dfd, struct filename *name); + +static inline long ksys_unlink(const char __user *pathname) +{ + return do_unlinkat(AT_FDCWD, getname(pathname)); +} + #endif diff --git a/init/do_mounts.h b/init/do_mounts.h index 5b05c8f93f47..401f90ee1eeb 100644 --- a/init/do_mounts.h +++ b/init/do_mounts.h @@ -16,7 +16,7 @@ extern int root_mountflags; static inline int create_dev(char *name, dev_t dev) { - sys_unlink(name); + ksys_unlink(name); return sys_mknod(name, S_IFBLK|0600, new_encode_dev(dev)); } diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c index 83f396d30b9a..e9e9e1c67d31 100644 --- a/init/do_mounts_initrd.c +++ b/init/do_mounts_initrd.c @@ -128,11 +128,11 @@ bool __init initrd_load(void) * mounted in the normal path. */ if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) { - sys_unlink("/initrd.image"); + ksys_unlink("/initrd.image"); handle_initrd(); return true; } } - sys_unlink("/initrd.image"); + ksys_unlink("/initrd.image"); return false; } diff --git a/init/do_mounts_rd.c b/init/do_mounts_rd.c index 2d365c398ccc..5b69056f610a 100644 --- a/init/do_mounts_rd.c +++ b/init/do_mounts_rd.c @@ -288,7 +288,7 @@ int __init rd_load_image(char *from) sys_close(out_fd); out: kfree(buf); - sys_unlink("/dev/ram"); + ksys_unlink("/dev/ram"); return res; } diff --git a/init/initramfs.c b/init/initramfs.c index 6f972df15bf2..08eb551168a8 100644 --- a/init/initramfs.c +++ b/init/initramfs.c @@ -319,7 +319,7 @@ static void __init clean_path(char *path, umode_t fmode) if (S_ISDIR(st.mode)) sys_rmdir(path); else - sys_unlink(path); + ksys_unlink(path); } } @@ -591,7 +591,7 @@ static void __init clean_rootfs(void) if (S_ISDIR(st.mode)) sys_rmdir(dirp->d_name); else - sys_unlink(dirp->d_name); + ksys_unlink(dirp->d_name); } num -= dirp->d_reclen; -- 2.16.3
