serial: mcf: don't take spinlocks in already protected functions

Don't take the port spinlock in uart functions where the serial core
already takes care of locking/unlocking them.

The code would actually lock up on architectures where spinlocks are
implemented.

Also protect calling mcf_rx_chars/mcf_tx_chars in the interrupt handler by
the port spinlock and use IRQ_RETVAL to return from isr.

[akpm@linux-foundation.org: make irq-handler return value more explicit]
Signed-off-by: Yury Georgievskiy <ygeorgie@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 13 insertions, 18 deletions

diff --git a/drivers/serial/mcf.c b/drivers/serial/mcf.c
index b5aaef965f24..3394b7cc1722 100644
--- a/drivers/serial/mcf.c
+++ b/drivers/serial/mcf.c
@@ -70,16 +70,14 @@ static unsigned int mcf_tx_empty(struct uart_port *port)
 static unsigned int mcf_get_mctrl(struct uart_port *port)
 {
         struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
-        unsigned long flags;
         unsigned int sigs;
 
-        spin_lock_irqsave(&port->lock, flags);
         sigs = (readb(port->membase + MCFUART_UIPR) & MCFUART_UIPR_CTS) ?
                 0 : TIOCM_CTS;
         sigs |= (pp->sigs & TIOCM_RTS);
         sigs |= (mcf_getppdcd(port->line) ? TIOCM_CD : 0);
         sigs |= (mcf_getppdtr(port->line) ? TIOCM_DTR : 0);
-        spin_unlock_irqrestore(&port->lock, flags);
+
         return sigs;
 }
 
@@ -88,16 +86,13 @@ static unsigned int mcf_get_mctrl(struct uart_port *port)
 static void mcf_set_mctrl(struct uart_port *port, unsigned int sigs)
 {
         struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
-        unsigned long flags;
 
-        spin_lock_irqsave(&port->lock, flags);
         pp->sigs = sigs;
         mcf_setppdtr(port->line, (sigs & TIOCM_DTR));
         if (sigs & TIOCM_RTS)
                 writeb(MCFUART_UOP_RTS, port->membase + MCFUART_UOP1);
         else
                 writeb(MCFUART_UOP_RTS, port->membase + MCFUART_UOP0);
-        spin_unlock_irqrestore(&port->lock, flags);
 }
 
 /****************************************************************************/
@@ -105,12 +100,9 @@ static void mcf_set_mctrl(struct uart_port *port, unsigned int sigs)
 static void mcf_start_tx(struct uart_port *port)
 {
         struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
-        unsigned long flags;
 
-        spin_lock_irqsave(&port->lock, flags);
         pp->imr |= MCFUART_UIR_TXREADY;
         writeb(pp->imr, port->membase + MCFUART_UIMR);
-        spin_unlock_irqrestore(&port->lock, flags);
 }
 
 /****************************************************************************/
@@ -118,12 +110,9 @@ static void mcf_start_tx(struct uart_port *port)
 static void mcf_stop_tx(struct uart_port *port)
 {
         struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
-        unsigned long flags;
 
-        spin_lock_irqsave(&port->lock, flags);
         pp->imr &= ~MCFUART_UIR_TXREADY;
         writeb(pp->imr, port->membase + MCFUART_UIMR);
-        spin_unlock_irqrestore(&port->lock, flags);
 }
 
 /****************************************************************************/
@@ -131,12 +120,9 @@ static void mcf_stop_tx(struct uart_port *port)
 static void mcf_stop_rx(struct uart_port *port)
 {
         struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
-        unsigned long flags;
 
-        spin_lock_irqsave(&port->lock, flags);
         pp->imr &= ~MCFUART_UIR_RXREADY;
         writeb(pp->imr, port->membase + MCFUART_UIMR);
-        spin_unlock_irqrestore(&port->lock, flags);
 }
 
 /****************************************************************************/
@@ -366,13 +352,22 @@ static irqreturn_t mcf_interrupt(int irq, void *data)
         struct uart_port *port = data;
         struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
         unsigned int isr;
+        irqreturn_t ret = IRQ_NONE;
 
         isr = readb(port->membase + MCFUART_UISR) & pp->imr;
-        if (isr & MCFUART_UIR_RXREADY)
+
+        spin_lock(&port->lock);
+        if (isr & MCFUART_UIR_RXREADY) {
                 mcf_rx_chars(pp);
-        if (isr & MCFUART_UIR_TXREADY)
+                ret = IRQ_HANDLED;
+        }
+        if (isr & MCFUART_UIR_TXREADY) {
                 mcf_tx_chars(pp);
-        return IRQ_HANDLED;
+                ret = IRQ_HANDLED;
+        }
+        spin_unlock(&port->lock);
+
+        return ret;
 }
 
 /****************************************************************************/