Commit cbb60b92 authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

fs: add ksys_ioctl() helper; remove in-kernel calls to sys_ioctl() 

Using this helper allows us to avoid the in-kernel calls to the
sys_ioctl() 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_ioctl().

After careful review, at least some of these calls could be converted
to do_vfs_ioctl() in future.

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: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent 454dab3f

fs/ioctl.c

+6 −1
Original line number Diff line number Diff line
@@ -689,7 +689,7 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd, 
	return error;

}



SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)

int ksys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg)

{

	int error;

	struct fd f = fdget(fd);
@@ -702,3 +702,8 @@ SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) 
	fdput(f);

	return error;

}



SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)

{

	return ksys_ioctl(fd, cmd, arg);

}

include/linux/syscalls.h

+1 −0
Original line number Diff line number Diff line
@@ -957,6 +957,7 @@ int ksys_fchmod(unsigned int fd, umode_t mode); 
int ksys_fchown(unsigned int fd, uid_t user, gid_t group);

int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,

		    unsigned int count);

int ksys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg);



/*

 * The following kernel syscall equivalents are just wrappers to fs-internal

init/do_mounts.c

+4 −4
Original line number Diff line number Diff line
@@ -491,18 +491,18 @@ void __init change_floppy(char *fmt, ...) 
	va_end(args);

	fd = ksys_open("/dev/root", O_RDWR | O_NDELAY, 0);

	if (fd >= 0) {

		sys_ioctl(fd, FDEJECT, 0);

		ksys_ioctl(fd, FDEJECT, 0);

		ksys_close(fd);

	}

	printk(KERN_NOTICE "VFS: Insert %s and press ENTER\n", buf);

	fd = ksys_open("/dev/console", O_RDWR, 0);

	if (fd >= 0) {

		sys_ioctl(fd, TCGETS, (long)&termios);

		ksys_ioctl(fd, TCGETS, (long)&termios);

		termios.c_lflag &= ~ICANON;

		sys_ioctl(fd, TCSETSF, (long)&termios);

		ksys_ioctl(fd, TCSETSF, (long)&termios);

		sys_read(fd, &c, 1);

		termios.c_lflag |= ICANON;

		sys_ioctl(fd, TCSETSF, (long)&termios);

		ksys_ioctl(fd, TCSETSF, (long)&termios);

		ksys_close(fd);

	}

}

init/do_mounts_initrd.c

+1 −1
Original line number Diff line number Diff line
@@ -110,7 +110,7 @@ static void __init handle_initrd(void) 
		if (fd < 0) {

			error = fd;

		} else {

			error = sys_ioctl(fd, BLKFLSBUF, 0);

			error = ksys_ioctl(fd, BLKFLSBUF, 0);

			ksys_close(fd);

		}

		printk(!error ? "okay\n" : "failed\n");

init/do_mounts_md.c

+8 −7
Original line number Diff line number Diff line
@@ -187,7 +187,7 @@ static void __init md_setup_drive(void) 
					"array %s\n", name);

			continue;

		}

		if (sys_ioctl(fd, SET_ARRAY_INFO, 0) == -EBUSY) {

		if (ksys_ioctl(fd, SET_ARRAY_INFO, 0) == -EBUSY) {

			printk(KERN_WARNING

			       "md: Ignoring md=%d, already autodetected. (Use raid=noautodetect)\n",

			       minor);
@@ -210,7 +210,7 @@ static void __init md_setup_drive(void) 
			ainfo.state = (1 << MD_SB_CLEAN);

			ainfo.layout = 0;

			ainfo.chunk_size = md_setup_args[ent].chunk;

			err = sys_ioctl(fd, SET_ARRAY_INFO, (long)&ainfo);

			err = ksys_ioctl(fd, SET_ARRAY_INFO, (long)&ainfo);

			for (i = 0; !err && i <= MD_SB_DISKS; i++) {

				dev = devices[i];

				if (!dev)
@@ -220,7 +220,8 @@ static void __init md_setup_drive(void) 
				dinfo.state = (1<<MD_DISK_ACTIVE)|(1<<MD_DISK_SYNC);

				dinfo.major = MAJOR(dev);

				dinfo.minor = MINOR(dev);

				err = sys_ioctl(fd, ADD_NEW_DISK, (long)&dinfo);

				err = ksys_ioctl(fd, ADD_NEW_DISK,

						 (long)&dinfo);

			}

		} else {

			/* persistent */
@@ -230,11 +231,11 @@ static void __init md_setup_drive(void) 
					break;

				dinfo.major = MAJOR(dev);

				dinfo.minor = MINOR(dev);

				sys_ioctl(fd, ADD_NEW_DISK, (long)&dinfo);

				ksys_ioctl(fd, ADD_NEW_DISK, (long)&dinfo);

			}

		}

		if (!err)

			err = sys_ioctl(fd, RUN_ARRAY, 0);

			err = ksys_ioctl(fd, RUN_ARRAY, 0);

		if (err)

			printk(KERN_WARNING "md: starting md%d failed\n", minor);

		else {
@@ -245,7 +246,7 @@ static void __init md_setup_drive(void) 
			 */

			ksys_close(fd);

			fd = ksys_open(name, 0, 0);

			sys_ioctl(fd, BLKRRPART, 0);

			ksys_ioctl(fd, BLKRRPART, 0);

		}

		ksys_close(fd);

	}
@@ -296,7 +297,7 @@ static void __init autodetect_raid(void) 


	fd = ksys_open("/dev/md0", 0, 0);

	if (fd >= 0) {

		sys_ioctl(fd, RAID_AUTORUN, raid_autopart);

		ksys_ioctl(fd, RAID_AUTORUN, raid_autopart);

		ksys_close(fd);

	}

}

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