USB: use mutex instead of semaphore in the USB gadget serial driver

The USB gadget serial driver uses a semaphore as mutex. Use the
mutex API instead of the (binary) semaphore.

Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@gmail.com>
Acked-by: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 13 insertions, 12 deletions

diff --git a/drivers/usb/gadget/serial.c b/drivers/usb/gadget/serial.c
index 38138bb9ddb0..9cd98e73dc1d 100644
--- a/drivers/usb/gadget/serial.c
+++ b/drivers/usb/gadget/serial.c
@@ -33,6 +33,7 @@
 #include <linux/device.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
+#include <linux/mutex.h>
 
 #include <asm/byteorder.h>
 #include <asm/io.h>
@@ -258,7 +259,7 @@ static const char *EP_IN_NAME;
 static const char *EP_OUT_NAME;
 static const char *EP_NOTIFY_NAME;
 
-static struct semaphore gs_open_close_sem[GS_NUM_PORTS];
+static struct mutex gs_open_close_lock[GS_NUM_PORTS];
 
 static unsigned int read_q_size = GS_DEFAULT_READ_Q_SIZE;
 static unsigned int write_q_size = GS_DEFAULT_WRITE_Q_SIZE;
@@ -595,7 +596,7 @@ static int __init gs_module_init(void)
         tty_set_operations(gs_tty_driver, &gs_tty_ops);
 
         for (i=0; i < GS_NUM_PORTS; i++)
-                sema_init(&gs_open_close_sem[i], 1);
+                mutex_init(&gs_open_close_lock[i]);
 
         retval = tty_register_driver(gs_tty_driver);
         if (retval) {
@@ -635,7 +636,7 @@ static int gs_open(struct tty_struct *tty, struct file *file)
         struct gs_port *port;
         struct gs_dev *dev;
         struct gs_buf *buf;
-        struct semaphore *sem;
+        struct mutex *mtx;
         int ret;
 
         port_num = tty->index;
@@ -656,10 +657,10 @@ static int gs_open(struct tty_struct *tty, struct file *file)
                 return -ENODEV;
         }
 
-        sem = &gs_open_close_sem[port_num];
-        if (down_interruptible(sem)) {
+        mtx = &gs_open_close_lock[port_num];
+        if (mutex_lock_interruptible(mtx)) {
                 printk(KERN_ERR
-                "gs_open: (%d,%p,%p) interrupted waiting for semaphore\n",
+                "gs_open: (%d,%p,%p) interrupted waiting for mutex\n",
                         port_num, tty, file);
                 return -ERESTARTSYS;
         }
@@ -754,12 +755,12 @@ static int gs_open(struct tty_struct *tty, struct file *file)
 
 exit_unlock_port:
         spin_unlock_irqrestore(&port->port_lock, flags);
-        up(sem);
+        mutex_unlock(mtx);
         return ret;
 
 exit_unlock_dev:
         spin_unlock_irqrestore(&dev->dev_lock, flags);
-        up(sem);
+        mutex_unlock(mtx);
         return ret;
 
 }
@@ -781,7 +782,7 @@ exit_unlock_dev:
 static void gs_close(struct tty_struct *tty, struct file *file)
 {
         struct gs_port *port = tty->driver_data;
-        struct semaphore *sem;
+        struct mutex *mtx;
 
         if (port == NULL) {
                 printk(KERN_ERR "gs_close: NULL port pointer\n");
@@ -790,8 +791,8 @@ static void gs_close(struct tty_struct *tty, struct file *file)
 
         gs_debug("gs_close: (%d,%p,%p)\n", port->port_num, tty, file);
 
-        sem = &gs_open_close_sem[port->port_num];
-        down(sem);
+        mtx = &gs_open_close_lock[port->port_num];
+        mutex_lock(mtx);
 
         spin_lock_irq(&port->port_lock);
 
@@ -846,7 +847,7 @@ static void gs_close(struct tty_struct *tty, struct file *file)
 
 exit:
         spin_unlock_irq(&port->port_lock);
-        up(sem);
+        mutex_unlock(mtx);
 }
 
 /*