Fix the (i)Stallion driver's putchar() and break_ctl() ops

Fix the Stallion driver's putchar() and break_ctl() ops and iStallion's
putchar() to return values.

Is it actually possible for putchar() or break_ctl() to be called with tty ==
NULL or can the check be discarded?

Should stl_write() be returning 0 if tty->driver_data is NULL or tx.buf is
NULL?  Is this even possible?

I've made Stallion's functions return -EINVAL as stli_breakctl() if the checks
fail.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/char/stallion.c

@@ -1025,7 +1025,7 @@ static int stl_write(struct tty_struct *tty, const unsigned char *buf, int count
 
 /*****************************************************************************/
 
-static void stl_putchar(struct tty_struct *tty, unsigned char ch)
+static int stl_putchar(struct tty_struct *tty, unsigned char ch)
 {
 	struct stlport	*portp;
 	unsigned int	len;
@@ -1034,12 +1034,12 @@ static void stl_putchar(struct tty_struct *tty, unsigned char ch)
 	pr_debug("stl_putchar(tty=%p,ch=%x)\n", tty, ch);
 
 	if (tty == NULL)
-		return;
+		return -EINVAL;
 	portp = tty->driver_data;
 	if (portp == NULL)
-		return;
+		return -EINVAL;
 	if (portp->tx.buf == NULL)
-		return;
+		return -EINVAL;
 
 	head = portp->tx.head;
 	tail = portp->tx.tail;
@@ -1053,6 +1053,7 @@ static void stl_putchar(struct tty_struct *tty, unsigned char ch)
 			head = portp->tx.buf;
 	}	
 	portp->tx.head = head;
+	return 0;
 }
 
 /*****************************************************************************/
@@ -1460,19 +1461,20 @@ static void stl_hangup(struct tty_struct *tty)
 
 /*****************************************************************************/
 
-static void stl_breakctl(struct tty_struct *tty, int state)
+static int stl_breakctl(struct tty_struct *tty, int state)
 {
 	struct stlport	*portp;
 
 	pr_debug("stl_breakctl(tty=%p,state=%d)\n", tty, state);
 
 	if (tty == NULL)
-		return;
+		return -EINVAL;
 	portp = tty->driver_data;
 	if (portp == NULL)
-		return;
+		return -EINVAL;
 
 	stl_sendbreak(portp, ((state == -1) ? 1 : 2));
+	return 0;
 }
 
 /*****************************************************************************/