Commit 4bdb9aca authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

fs: add kern_select() helper; remove in-kernel call to sys_select() 

Using this helper allows us to avoid the in-kernel call to the sys_umount()
syscall.

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.GA17492@light.dominikbrodowski.net



Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent 30cfe4ef

fs/select.c

+9 −3
Original line number Diff line number Diff line
@@ -675,8 +675,8 @@ int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, 
	return ret;

}



SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,

		fd_set __user *, exp, struct timeval __user *, tvp)

static int kern_select(int n, fd_set __user *inp, fd_set __user *outp,

		       fd_set __user *exp, struct timeval __user *tvp)

{

	struct timespec64 end_time, *to = NULL;

	struct timeval tv;
@@ -699,6 +699,12 @@ SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp, 
	return ret;

}



SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,

		fd_set __user *, exp, struct timeval __user *, tvp)

{

	return kern_select(n, inp, outp, exp, tvp);

}



static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp,

		       fd_set __user *exp, struct timespec __user *tsp,

		       const sigset_t __user *sigmask, size_t sigsetsize)
@@ -784,7 +790,7 @@ SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg) 


	if (copy_from_user(&a, arg, sizeof(a)))

		return -EFAULT;

	return sys_select(a.n, a.inp, a.outp, a.exp, a.tvp);

	return kern_select(a.n, a.inp, a.outp, a.exp, a.tvp);

}

#endif