Using this helper allows us to avoid the in-kernel call to the sys_setsid() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_setsid().
This patch is part of a series which tries to remove in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. Cc: Al Viro <[email protected]> Signed-off-by: Dominik Brodowski <[email protected]> --- include/linux/syscalls.h | 1 + init/do_mounts_initrd.c | 2 +- kernel/sys.c | 7 ++++++- 3 files changed, 8 insertions(+), 2 deletions(-) diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index a3f42f5f3b08..c509459ce9d5 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -981,6 +981,7 @@ ssize_t ksys_pread64(unsigned int fd, char __user *buf, size_t count, ssize_t ksys_pwrite64(unsigned int fd, const char __user *buf, size_t count, loff_t pos); int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len); +int ksys_setsid(void); /* * The following kernel syscall equivalents are just wrappers to fs-internal diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c index d1d3e53bdeef..5a91aefa7305 100644 --- a/init/do_mounts_initrd.c +++ b/init/do_mounts_initrd.c @@ -45,7 +45,7 @@ static int init_linuxrc(struct subprocess_info *info, struct cred *new) ksys_chdir("/root"); ksys_mount(".", "/", NULL, MS_MOVE, NULL); ksys_chroot("."); - sys_setsid(); + ksys_setsid(); return 0; } diff --git a/kernel/sys.c b/kernel/sys.c index ebb138b841c8..8eda25dcbbd4 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1108,7 +1108,7 @@ static void set_special_pids(struct pid *pid) change_pid(curr, PIDTYPE_PGID, pid); } -SYSCALL_DEFINE0(setsid) +int ksys_setsid(void) { struct task_struct *group_leader = current->group_leader; struct pid *sid = task_pid(group_leader); @@ -1141,6 +1141,11 @@ SYSCALL_DEFINE0(setsid) return err; } +SYSCALL_DEFINE0(setsid) +{ + return ksys_setsid(); +} + DECLARE_RWSEM(uts_sem); #ifdef COMPAT_UTS_MACHINE -- 2.16.2
