tty: We want the port object to be persistent

Move the tty_port and uart_info bits around a little. By embedding the uart_info
into the uart_port we get rid of lots of corner case testing and also get the
ability to go port<->state<->info which is a bit more elegant than the current
data structures.

Downsides - we allocate a tiny bit more memory for unused ports, upside we've
removed as much code as it saved for most users..
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/serial/jsm/jsm_tty.c

@@ -272,7 +272,7 @@ static void jsm_tty_close(struct uart_port *port)
 	jsm_printk(CLOSE, INFO, &channel->ch_bd->pci_dev, "start\n");
 
 	bd = channel->ch_bd;
-	ts = channel->uart_port.info->port.tty->termios;
+	ts = port->info->port.tty->termios;
 
 	channel->ch_flags &= ~(CH_STOPI);
 

include/linux/serial_core.h

@@ -315,36 +315,14 @@ struct uart_port {
 	void			*private_data;		/* generic platform data pointer */
 };
 
-/*
- * This is the state information which is persistent across opens.
- * The low level driver must not to touch any elements contained
- * within.
- */
-struct uart_state {
-	unsigned int		close_delay;		/* msec */
-	unsigned int		closing_wait;		/* msec */
-
-#define USF_CLOSING_WAIT_INF	(0)
-#define USF_CLOSING_WAIT_NONE	(~0U)
-
-	int			count;
-	int			pm_state;
-	struct uart_info	*info;
-	struct uart_port	*port;
-
-	struct mutex		mutex;
-};
-
-#define UART_XMIT_SIZE	PAGE_SIZE
-
-typedef unsigned int __bitwise__ uif_t;
-
 /*
  * This is the state information which is only valid when the port
- * is open; it may be freed by the core driver once the device has
+ * is open; it may be cleared the core driver once the device has
  * been closed.  Either the low level driver or the core can modify
  * stuff here.
  */
+typedef unsigned int __bitwise__ uif_t;
+
 struct uart_info {
 	struct tty_port		port;
 	struct circ_buf		xmit;
@@ -366,6 +344,29 @@ struct uart_info {
 	wait_queue_head_t	delta_msr_wait;
 };
 
+/*
+ * This is the state information which is persistent across opens.
+ * The low level driver must not to touch any elements contained
+ * within.
+ */
+struct uart_state {
+	unsigned int		close_delay;		/* msec */
+	unsigned int		closing_wait;		/* msec */
+
+#define USF_CLOSING_WAIT_INF	(0)
+#define USF_CLOSING_WAIT_NONE	(~0U)
+
+	int			count;
+	int			pm_state;
+	struct uart_info	info;
+	struct uart_port	*port;
+
+	struct mutex		mutex;
+};
+
+#define UART_XMIT_SIZE	PAGE_SIZE
+
+
 /* number of characters left in xmit buffer before we ask for more */
 #define WAKEUP_CHARS		256
 
@@ -439,8 +440,13 @@ int uart_resume_port(struct uart_driver *reg, struct uart_port *port);
 #define uart_circ_chars_free(circ)	\
 	(CIRC_SPACE((circ)->head, (circ)->tail, UART_XMIT_SIZE))
 
-#define uart_tx_stopped(portp)		\
-	((portp)->info->port.tty->stopped || (portp)->info->port.tty->hw_stopped)
+static inline int uart_tx_stopped(struct uart_port *port)
+{
+	struct tty_struct *tty = port->info->port.tty;
+	if(tty->stopped || tty->hw_stopped)
+		return 1;
+	return 0;
+}
 
 /*
  * The following are helper functions for the low level drivers.
@@ -451,7 +457,7 @@ uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
 #ifdef SUPPORT_SYSRQ
 	if (port->sysrq) {
 		if (ch && time_before(jiffies, port->sysrq)) {
-			handle_sysrq(ch, port->info ? port->info->port.tty : NULL);
+			handle_sysrq(ch, port->info->port.tty);
 			port->sysrq = 0;
 			return 1;
 		}