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 1d65b4a088de ("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>

diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index e18f318..4de1c6d 100644 (file)
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -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);

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 10212c6..67c7a07 100644 (file)
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -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;

diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 3584462..61c3372 100644 (file)
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -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);