Commit e0efb316 authored by Jann Horn's avatar Jann Horn Committed by Greg Kroah-Hartman
Browse files

tty: Remove dead termiox code 



set_termiox() and the TCGETX handler bail out with -EINVAL immediately
if ->termiox is NULL, but there are no code paths that can set
->termiox to a non-NULL pointer; and no such code paths seem to have
existed since the termiox mechanism was introduced back in
commit 1d65b4a0 ("tty: Add termiox") in v2.6.28.
Similarly, no driver actually implements .set_termiox; and it looks like
no driver ever has.

Delete this dead code; but leave the definition of struct termiox in the
UAPI headers intact.

Signed-off-by: default avatarJann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20201203020331.2394754-1-jannh@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent aef1b6a2

drivers/tty/tty_ioctl.c

+2 −59
Original line number Diff line number Diff line
@@ -443,51 +443,6 @@ static int get_termio(struct tty_struct *tty, struct termio __user *termio) 
	return 0;

}





#ifdef TCGETX



/**

 *	set_termiox	-	set termiox fields if possible

 *	@tty: terminal

 *	@arg: termiox structure from user

 *	@opt: option flags for ioctl type

 *

 *	Implement the device calling points for the SYS5 termiox ioctl

 *	interface in Linux

 */



static int set_termiox(struct tty_struct *tty, void __user *arg, int opt)

{

	struct termiox tnew;

	struct tty_ldisc *ld;



	if (tty->termiox == NULL)

		return -EINVAL;

	if (copy_from_user(&tnew, arg, sizeof(struct termiox)))

		return -EFAULT;



	ld = tty_ldisc_ref(tty);

	if (ld != NULL) {

		if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)

			ld->ops->flush_buffer(tty);

		tty_ldisc_deref(ld);

	}

	if (opt & TERMIOS_WAIT) {

		tty_wait_until_sent(tty, 0);

		if (signal_pending(current))

			return -ERESTARTSYS;

	}



	down_write(&tty->termios_rwsem);

	if (tty->ops->set_termiox)

		tty->ops->set_termiox(tty, &tnew);

	up_write(&tty->termios_rwsem);

	return 0;

}



#endif





#ifdef TIOCGETP

/*

 * These are deprecated, but there is limited support..
@@ -815,23 +770,11 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file, 
		return ret;

#endif

#ifdef TCGETX

	case TCGETX: {

		struct termiox ktermx;

		if (real_tty->termiox == NULL)

			return -EINVAL;

		down_read(&real_tty->termios_rwsem);

		memcpy(&ktermx, real_tty->termiox, sizeof(struct termiox));

		up_read(&real_tty->termios_rwsem);

		if (copy_to_user(p, &ktermx, sizeof(struct termiox)))

			ret = -EFAULT;

		return ret;

	}

	case TCGETX:

	case TCSETX:

		return set_termiox(real_tty, p, 0);

	case TCSETXW:

		return set_termiox(real_tty, p, TERMIOS_WAIT);

	case TCSETXF:

		return set_termiox(real_tty, p, TERMIOS_FLUSH);

		return -EINVAL;

#endif		

	case TIOCGSOFTCAR:

		copy_termios(real_tty, &kterm);

include/linux/tty.h

+0 −1
Original line number Diff line number Diff line
@@ -303,7 +303,6 @@ struct tty_struct { 
	spinlock_t flow_lock;

	/* Termios values are protected by the termios rwsem */

	struct ktermios termios, termios_locked;

	struct termiox *termiox;	/* May be NULL for unsupported */

	char name[64];

	struct pid *pgrp;		/* Protected by ctrl lock */

	struct pid *session;

include/linux/tty_driver.h

+0 −9
Original line number Diff line number Diff line
@@ -224,14 +224,6 @@ 
 *	line). See tty_do_resize() if you need to wrap the standard method

 *	in your own logic - the usual case.

 *

 * void (*set_termiox)(struct tty_struct *tty, struct termiox *new);

 *

 *	Called when the device receives a termiox based ioctl. Passes down

 *	the requested data from user space. This method will not be invoked

 *	unless the tty also has a valid tty->termiox pointer.

 *

 *	Optional: Called under the termios lock

 *

 * int (*get_icount)(struct tty_struct *tty, struct serial_icounter *icount);

 *

 *	Called when the device receives a TIOCGICOUNT ioctl. Passed a kernel
@@ -285,7 +277,6 @@ struct tty_operations { 
	int (*tiocmset)(struct tty_struct *tty,

			unsigned int set, unsigned int clear);

	int (*resize)(struct tty_struct *tty, struct winsize *ws);

	int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);

	int (*get_icount)(struct tty_struct *tty,

				struct serial_icounter_struct *icount);

	int  (*get_serial)(struct tty_struct *tty, struct serial_struct *p);