TTY/serial fixes for 3.13-rc2

Here are some tty/serial driver fixes for reported issues in 3.13-rc2.
 
 The n_gsm "fix" was reverted as it was found to not be correct.
 Hopefully this will be resolved in a future pull request, but as there's
 really only one user of this line setting, it's not a big deal...
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-3.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial fixes from Greg KH:
 "Here are some tty/serial driver fixes for reported issues in 3.13-rc2.

  The n_gsm "fix" was reverted as it was found to not be correct.
  Hopefully this will be resolved in a future pull request, but as
  there's really only one user of this line setting, it's not a big
  deal..."

* tag 'tty-3.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  Revert "n_gsm: race between ld close and gsmtty open"
  n_tty: Protect minimum_to_wake reset for concurrent readers
  tty: Reset hupped state on open
  TTY: amiserial, add missing platform check
  TTY: pmac_zilog, check existence of ports in pmz_console_init()
  n_gsm: race between ld close and gsmtty open
  tty/serial/8250: fix typo in help text
  n_tty: Fix 4096-byte canonical reads
  n_tty: Fix echo overrun tail computation
  n_tty: Ensure reader restarts worker for next reader

drivers/tty/amiserial.c

@@ -1855,6 +1855,9 @@ static struct console sercons = {
  */
 static int __init amiserial_console_init(void)
 {
+	if (!MACH_IS_AMIGA)
+		return -ENODEV;
+
 	register_console(&sercons);
 	return 0;
 }

drivers/tty/n_tty.c

@@ -768,7 +768,7 @@ static size_t __process_echoes(struct tty_struct *tty)
 	 * data at the tail to prevent a subsequent overrun */
 	while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
 		if (echo_buf(ldata, tail) == ECHO_OP_START) {
-			if (echo_buf(ldata, tail) == ECHO_OP_ERASE_TAB)
+			if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
 				tail += 3;
 			else
 				tail += 2;
@@ -1998,7 +1998,10 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 		found = 1;
 
 	size = N_TTY_BUF_SIZE - tail;
-	n = (found + eol + size) & (N_TTY_BUF_SIZE - 1);
+	n = eol - tail;
+	if (n > 4096)
+		n += 4096;
+	n += found;
 	c = n;
 
 	if (found && read_buf(ldata, eol) == __DISABLED_CHAR) {
@@ -2243,18 +2246,19 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 		if (time)
 			timeout = time;
 	}
-	mutex_unlock(&ldata->atomic_read_lock);
+	n_tty_set_room(tty);
-	remove_wait_queue(&tty->read_wait, &wait);
+	up_read(&tty->termios_rwsem);
 
+	remove_wait_queue(&tty->read_wait, &wait);
 	if (!waitqueue_active(&tty->read_wait))
 		ldata->minimum_to_wake = minimum;
 
+	mutex_unlock(&ldata->atomic_read_lock);
+
 	__set_current_state(TASK_RUNNING);
 	if (b - buf)
 		retval = b - buf;
 
-	n_tty_set_room(tty);
-	up_read(&tty->termios_rwsem);
 	return retval;
 }
 

drivers/tty/serial/8250/Kconfig

@@ -41,7 +41,7 @@ config SERIAL_8250_DEPRECATED_OPTIONS
 	  accept kernel parameters in both forms like 8250_core.nr_uarts=4 and
 	  8250.nr_uarts=4. We now renamed the module back to 8250, but if
 	  anybody noticed in 3.7 and changed their userspace we still have to
-	  keep the 8350_core.* options around until they revert the changes
+	  keep the 8250_core.* options around until they revert the changes
 	  they already did.
 
 	  If 8250 is built as a module, this adds 8250_core alias instead. 

drivers/tty/serial/pmac_zilog.c

@@ -2052,6 +2052,9 @@ static int __init pmz_console_init(void)
 	/* Probe ports */
 	pmz_probe();
 
+	if (pmz_ports_count == 0)
+		return -ENODEV;
+
 	/* TODO: Autoprobe console based on OF */
 	/* pmz_console.index = i; */
 	register_console(&pmz_console);

drivers/tty/tty_io.c

@@ -2086,6 +2086,7 @@ retry_open:
 			filp->f_op = &tty_fops;
 		goto retry_open;
 	}
+	clear_bit(TTY_HUPPED, &tty->flags);
 	tty_unlock(tty);