[SERIAL] Locking fixup (part 1)

After the last few days of debugging, we've ended up with the caller
of the start_tx and stop_tx methods taking the per-port lock.  This
cset and the accompanying csets make the same change to some of the
other methods for consistency reasons.  Since these methods don't
contain a lot of code, it is better that they have consistent locking
rules.

This cset fixes up the stop_rx method.

Documentation/serial/driver

@@ -138,8 +138,8 @@ hardware.
 	Stop receiving characters; the port is in the process of
 	being closed.
 
-	Locking: none.
-	Interrupts: caller dependent.
+	Locking: port->lock taken.
+	Interrupts: locally disabled.
 	This call must not sleep
 
   enable_ms(port)

drivers/serial/21285.c

@@ -85,14 +85,10 @@ serial21285_start_tx(struct uart_port *port, unsigned int tty_start)
 
 static void serial21285_stop_rx(struct uart_port *port)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&port->lock, flags);
 	if (rx_enabled(port)) {
 		disable_irq(IRQ_CONRX);
 		rx_enabled(port) = 0;
 	}
-	spin_unlock_irqrestore(&port->lock, flags);
 }
 
 static void serial21285_enable_ms(struct uart_port *port)

drivers/serial/8250.c

@@ -724,13 +724,10 @@ static void serial8250_start_tx(struct uart_port *port, unsigned int tty_start)
 static void serial8250_stop_rx(struct uart_port *port)
 {
 	struct uart_8250_port *up = (struct uart_8250_port *)port;
-	unsigned long flags;
 
-	spin_lock_irqsave(&up->port.lock, flags);
 	up->ier &= ~UART_IER_RLSI;
 	up->port.read_status_mask &= ~UART_LSR_DR;
 	serial_out(up, UART_IER, up->ier);
-	spin_unlock_irqrestore(&up->port.lock, flags);
 }
 
 static void serial8250_enable_ms(struct uart_port *port)

drivers/serial/amba.c

@@ -138,14 +138,11 @@ static void ambauart_start_tx(struct uart_port *port, unsigned int tty_start)
 
 static void ambauart_stop_rx(struct uart_port *port)
 {
-	unsigned long flags;
 	unsigned int cr;
 
-	spin_lock_irqsave(&port->lock, flags);
 	cr = UART_GET_CR(port);
 	cr &= ~(AMBA_UARTCR_RIE | AMBA_UARTCR_RTIE);
 	UART_PUT_CR(port, cr);
-	spin_unlock_irqrestore(&port->lock, flags);
 }
 
 static void ambauart_enable_ms(struct uart_port *port)

drivers/serial/anakin.c

@@ -119,13 +119,9 @@ anakin_start_tx(struct uart_port *port, unsigned int tty_start)
 static void
 anakin_stop_rx(struct uart_port *port)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&port->lock, flags);
 	while (anakin_in(port, 0x10) & RXRELEASE) 
 	    anakin_in(port, 0x14);
 	anakin_out(port, 0x18, anakin_in(port, 0x18) | BLOCKRX);
-	spin_unlock_irqrestore(&port->lock, flags);
 }
 
 static void

drivers/serial/core.c

@@ -1200,7 +1200,9 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 	 * disable the receive line status interrupts.
 	 */
 	if (info->flags & UIF_INITIALIZED) {
+		spin_lock_irqsave(&port->lock, flags);
 		port->ops->stop_rx(port);
+		spin_unlock_irqrestore(&port->lock, flags);
 		/*
 		 * Before we drop DTR, make sure the UART transmitter
 		 * has completely drained; this is especially
@@ -1948,8 +1950,8 @@ static int uart_pm_set_state(struct uart_state *state, int pm_state, int oldstat
 			spin_lock_irq(&port->lock);
 			ops->stop_tx(port, 0);
 			ops->set_mctrl(port, 0);
-			spin_unlock_irq(&port->lock);
 			ops->stop_rx(port);
+			spin_unlock_irq(&port->lock);
 			ops->shutdown(port);
 		}
 		if (ops->pm)

drivers/serial/sa1100.c

@@ -190,13 +190,10 @@ static void sa1100_start_tx(struct uart_port *port, unsigned int tty_start)
 static void sa1100_stop_rx(struct uart_port *port)
 {
 	struct sa1100_port *sport = (struct sa1100_port *)port;
-	unsigned long flags;
 	u32 utcr3;
 
-	spin_lock_irqsave(&sport->port.lock, flags);
 	utcr3 = UART_GET_UTCR3(sport);
 	UART_PUT_UTCR3(sport, utcr3 & ~UTCR3_RIE);
-	spin_unlock_irqrestore(&sport->port.lock, flags);
 }
 
 /*