tty/serial: lay the foundations for the next set of reworks

- Stop drivers calling their own flush method indirectly, it obfuscates code
  and it will change soon anyway

- A few more lock_kernel paths temporarily needed in some driver internal
  waiting code

- Remove private put_char method that does a write call for one char - we
  have that anyway

- Most but not yet all of the termios copy under lock fixing (some has other
  dependencies to follow)

- Note a few locking bugs in drivers found in the process

- Kill remaining [ab]users of TIOCG/SSOFTCAR in the driver, these must go to
  fix the termios locking

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 2 deletions

diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c
index d769e43f73fb..8c4bf3e48d5b 100644
--- a/drivers/char/tty_ioctl.c
+++ b/drivers/char/tty_ioctl.c
@@ -396,7 +396,7 @@ EXPORT_SYMBOL(tty_termios_hw_change);
 static void change_termios(struct tty_struct *tty, struct ktermios *new_termios)
 {
         int canon_change;
-        struct ktermios old_termios = *tty->termios;
+        struct ktermios old_termios;
         struct tty_ldisc *ld;
         unsigned long flags;
 
@@ -408,7 +408,7 @@ static void change_termios(struct tty_struct *tty, struct ktermios *new_termios)
         /* FIXME: we need to decide on some locking/ordering semantics
            for the set_termios notification eventually */
         mutex_lock(&tty->termios_mutex);
-
+        old_termios = *tty->termios;
         *tty->termios = *new_termios;
         unset_locked_termios(tty->termios, &old_termios, tty->termios_locked);
         canon_change = (old_termios.c_lflag ^ tty->termios->c_lflag) & ICANON;
@@ -480,7 +480,9 @@ static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
         if (retval)
                 return retval;
 
+        mutex_lock(&tty->termios_mutex);
         memcpy(&tmp_termios, tty->termios, sizeof(struct ktermios));
+        mutex_unlock(&tty->termios_mutex);
 
         if (opt & TERMIOS_TERMIO) {
                 if (user_termio_to_kernel_termios(&tmp_termios,
@@ -666,12 +668,14 @@ static int get_tchars(struct tty_struct *tty, struct tchars __user *tchars)
 {
         struct tchars tmp;
 
+        mutex_lock(&tty->termios_mutex);
         tmp.t_intrc = tty->termios->c_cc[VINTR];
         tmp.t_quitc = tty->termios->c_cc[VQUIT];
         tmp.t_startc = tty->termios->c_cc[VSTART];
         tmp.t_stopc = tty->termios->c_cc[VSTOP];
         tmp.t_eofc = tty->termios->c_cc[VEOF];
         tmp.t_brkc = tty->termios->c_cc[VEOL2]; /* what is brkc anyway? */
+        mutex_unlock(&tty->termios_mutex);
         return copy_to_user(tchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 }
 
@@ -681,12 +685,14 @@ static int set_tchars(struct tty_struct *tty, struct tchars __user *tchars)
 
         if (copy_from_user(&tmp, tchars, sizeof(tmp)))
                 return -EFAULT;
+        mutex_lock(&tty->termios_mutex);
         tty->termios->c_cc[VINTR] = tmp.t_intrc;
         tty->termios->c_cc[VQUIT] = tmp.t_quitc;
         tty->termios->c_cc[VSTART] = tmp.t_startc;
         tty->termios->c_cc[VSTOP] = tmp.t_stopc;
         tty->termios->c_cc[VEOF] = tmp.t_eofc;
         tty->termios->c_cc[VEOL2] = tmp.t_brkc; /* what is brkc anyway? */
+        mutex_unlock(&tty->termios_mutex);
         return 0;
 }
 #endif
@@ -696,6 +702,7 @@ static int get_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
 {
         struct ltchars tmp;
 
+        mutex_lock(&tty->termios_mutex);
         tmp.t_suspc = tty->termios->c_cc[VSUSP];
         /* what is dsuspc anyway? */
         tmp.t_dsuspc = tty->termios->c_cc[VSUSP];
@@ -704,6 +711,7 @@ static int get_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
         tmp.t_flushc = tty->termios->c_cc[VEOL2];
         tmp.t_werasc = tty->termios->c_cc[VWERASE];
         tmp.t_lnextc = tty->termios->c_cc[VLNEXT];
+        mutex_unlock(&tty->termios_mutex);
         return copy_to_user(ltchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 }
 
@@ -714,6 +722,7 @@ static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
         if (copy_from_user(&tmp, ltchars, sizeof(tmp)))
                 return -EFAULT;
 
+        mutex_lock(&tty->termios_mutex);
         tty->termios->c_cc[VSUSP] = tmp.t_suspc;
         /* what is dsuspc anyway? */
         tty->termios->c_cc[VEOL2] = tmp.t_dsuspc;
@@ -722,6 +731,7 @@ static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
         tty->termios->c_cc[VEOL2] = tmp.t_flushc;
         tty->termios->c_cc[VWERASE] = tmp.t_werasc;
         tty->termios->c_cc[VLNEXT] = tmp.t_lnextc;
+        mutex_unlock(&tty->termios_mutex);
         return 0;
 }
 #endif