Commit 2ca2a09d authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

fs: add ksys_close() wrapper; remove in-kernel calls to sys_close() 

Using the ksys_close() wrapper allows us to get rid of in-kernel calls
to the sys_close() 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_close(), with one subtle
difference:

The few places which checked the return value did not care about the return
value re-writing in sys_close(), so simply use a wrapper around
__close_fd().

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 411d9475

fs/autofs4/dev-ioctl.c

+1 −1
Original line number Diff line number Diff line
@@ -310,7 +310,7 @@ static int autofs_dev_ioctl_closemount(struct file *fp, 
				       struct autofs_sb_info *sbi,

				       struct autofs_dev_ioctl *param)

{

	return sys_close(param->ioctlfd);

	return ksys_close(param->ioctlfd);

}



/*

fs/binfmt_misc.c

+1 −1
Original line number Diff line number Diff line
@@ -241,7 +241,7 @@ ret: 
	return retval;

error:

	if (fd_binary > 0)

		sys_close(fd_binary);

		ksys_close(fd_binary);

	bprm->interp_flags = 0;

	bprm->interp_data = 0;

	goto ret;

fs/file.c

+1 −0
Original line number Diff line number Diff line
@@ -638,6 +638,7 @@ out_unlock: 
	spin_unlock(&files->file_lock);

	return -EBADF;

}

EXPORT_SYMBOL(__close_fd); /* for ksys_close() */



void do_close_on_exec(struct files_struct *files)

{

fs/open.c

+0 −1
Original line number Diff line number Diff line
@@ -1200,7 +1200,6 @@ SYSCALL_DEFINE1(close, unsigned int, fd) 


	return retval;

}

EXPORT_SYMBOL(sys_close);



/*

 * This routine simulates a hangup on the tty, to arrange that users

include/linux/syscalls.h

+12 −0
Original line number Diff line number Diff line
@@ -1045,4 +1045,16 @@ static inline long ksys_ftruncate(unsigned int fd, unsigned long length) 
	return do_sys_ftruncate(fd, length, 1);

}



extern int __close_fd(struct files_struct *files, unsigned int fd);



/*

 * In contrast to sys_close(), this stub does not check whether the syscall

 * should or should not be restarted, but returns the raw error codes from

 * __close_fd().

 */

static inline int ksys_close(unsigned int fd)

{

	return __close_fd(current->files, fd);

}



#endif

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