dz: fix locking issues

The ->start_tx(), ->stop_tx() and ->stop_rx() backends are called with the
port's lock already taken.  Remove locking from within them and wrap around
calls as necessary.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 11 deletions

diff --git a/drivers/serial/dz.c b/drivers/serial/dz.c
index c2f867777145..656c342a80f8 100644
--- a/drivers/serial/dz.c
+++ b/drivers/serial/dz.c
@@ -108,37 +108,28 @@ static void dz_stop_tx(struct uart_port *uport)
 {
         struct dz_port *dport = (struct dz_port *)uport;
         unsigned short tmp, mask = 1 << dport->port.line;
-        unsigned long flags;
 
-        spin_lock_irqsave(&dport->port.lock, flags);
         tmp = dz_in(dport, DZ_TCR);     /* read the TX flag */
         tmp &= ~mask;                   /* clear the TX flag */
         dz_out(dport, DZ_TCR, tmp);
-        spin_unlock_irqrestore(&dport->port.lock, flags);
 }
 
 static void dz_start_tx(struct uart_port *uport)
 {
         struct dz_port *dport = (struct dz_port *)uport;
         unsigned short tmp, mask = 1 << dport->port.line;
-        unsigned long flags;
 
-        spin_lock_irqsave(&dport->port.lock, flags);
         tmp = dz_in(dport, DZ_TCR);     /* read the TX flag */
         tmp |= mask;                    /* set the TX flag */
         dz_out(dport, DZ_TCR, tmp);
-        spin_unlock_irqrestore(&dport->port.lock, flags);
 }
 
 static void dz_stop_rx(struct uart_port *uport)
 {
         struct dz_port *dport = (struct dz_port *)uport;
-        unsigned long flags;
 
-        spin_lock_irqsave(&dport->port.lock, flags);
         dport->cflag &= ~DZ_CREAD;
         dz_out(dport, DZ_LPR, dport->cflag | dport->port.line);
-        spin_unlock_irqrestore(&dport->port.lock, flags);
 }
 
 static void dz_enable_ms(struct uart_port *port)
@@ -268,7 +259,9 @@ static inline void dz_transmit_chars(struct dz_port *dport_in)
         }
         /* If nothing to do or stopped or hardware stopped. */
         if (uart_circ_empty(xmit) || uart_tx_stopped(&dport->port)) {
+                spin_lock(&dport->port.lock);
                 dz_stop_tx(&dport->port);
+                spin_unlock(&dport->port.lock);
                 return;
         }
 
@@ -285,8 +278,11 @@ static inline void dz_transmit_chars(struct dz_port *dport_in)
                 uart_write_wakeup(&dport->port);
 
         /* Are we are done. */
-        if (uart_circ_empty(xmit))
+        if (uart_circ_empty(xmit)) {
+                spin_lock(&dport->port.lock);
                 dz_stop_tx(&dport->port);
+                spin_unlock(&dport->port.lock);
+        }
 }
 
 /*
@@ -417,7 +413,12 @@ static int dz_startup(struct uart_port *uport)
  */
 static void dz_shutdown(struct uart_port *uport)
 {
-        dz_stop_tx(uport);
+        struct dz_port *dport = (struct dz_port *)uport;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dport->port.lock, flags);
+        dz_stop_tx(&dport->port);
+        spin_unlock_irqrestore(&dport->port.lock, flags);
 }
 
 /*