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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 1d65b4a088 ("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: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20201203020331.2394754-1-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
zero-sugar-mainline-defconfig
Jann Horn 2020-12-03 03:03:31 +01:00 committed by Greg Kroah-Hartman
parent aef1b6a279
commit e0efb3168d
3 changed files with 2 additions and 69 deletions
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61
drivers/tty/tty_ioctl.c
View File

@ -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);

1
include/linux/tty.h
View File

@ -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;

9
include/linux/tty_driver.h
View File

@ -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);