[PATCH] USB serial: Converts port semaphore to mutexes.

The usbserial's port semaphore used to synchronize serial_open()
and serial_close() are strict mutexes, convert them to the mutex
implementation.

Signed-off-by: Luiz Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/usb-serial.c

@@ -27,10 +27,10 @@
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/spinlock.h>
+#include <linux/mutex.h>
 #include <linux/list.h>
 #include <linux/smp_lock.h>
 #include <asm/uaccess.h>
-#include <asm/semaphore.h>
 #include <linux/usb.h>
 #include "usb-serial.h"
 #include "pl2303.h"
@@ -192,7 +192,7 @@ static int serial_open (struct tty_struct *tty, struct file * filp)
 	if (!port)
 		return -ENODEV;
 
-	if (down_interruptible(&port->sem))
+	if (mutex_lock_interruptible(&port->mutex))
 		return -ERESTARTSYS;
 
 	++port->open_count;
@@ -219,15 +219,15 @@ static int serial_open (struct tty_struct *tty, struct file * filp)
 			goto bailout_module_put;
 	}
 
-	up(&port->sem);
+	mutex_unlock(&port->mutex);
 	return 0;
 
 bailout_module_put:
 	module_put(serial->type->driver.owner);
 bailout_kref_put:
 	kref_put(&serial->kref, destroy_serial);
 	port->open_count = 0;
-	up(&port->sem);
+	mutex_unlock(&port->mutex);
 	return retval;
 }
 
@@ -240,10 +240,10 @@ static void serial_close(struct tty_struct *tty, struct file * filp)
 
 	dbg("%s - port %d", __FUNCTION__, port->number);
 
-	down(&port->sem);
+	mutex_lock(&port->mutex);
 
 	if (port->open_count == 0) {
-		up(&port->sem);
+		mutex_unlock(&port->mutex);
 		return;
 	}
 
@@ -262,7 +262,7 @@ static void serial_close(struct tty_struct *tty, struct file * filp)
 		module_put(port->serial->type->driver.owner);
 	}
 
-	up(&port->sem);
+	mutex_unlock(&port->mutex);
 	kref_put(&port->serial->kref, destroy_serial);
 }
 
@@ -783,7 +783,7 @@ int usb_serial_probe(struct usb_interface *interface,
 		port->number = i + serial->minor;
 		port->serial = serial;
 		spin_lock_init(&port->lock);
-		sema_init(&port->sem, 1);
+		mutex_init(&port->mutex);
 		INIT_WORK(&port->work, usb_serial_port_softint, port);
 		serial->port[i] = port;
 	}

drivers/usb/serial/usb-serial.h

@@ -16,7 +16,7 @@
 
 #include <linux/config.h>
 #include <linux/kref.h>
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
 
 #define SERIAL_TTY_MAJOR	188	/* Nice legal number now */
 #define SERIAL_TTY_MINORS	255	/* loads of devices :) */
@@ -31,7 +31,7 @@
  * @serial: pointer back to the struct usb_serial owner of this port.
  * @tty: pointer to the corresponding tty for this port.
  * @lock: spinlock to grab when updating portions of this structure.
- * @sem: semaphore used to synchronize serial_open() and serial_close()
+ * @mutex: mutex used to synchronize serial_open() and serial_close()
  *	access for this port.
  * @number: the number of the port (the minor number).
  * @interrupt_in_buffer: pointer to the interrupt in buffer for this port.
@@ -63,7 +63,7 @@ struct usb_serial_port {
 	struct usb_serial *	serial;
 	struct tty_struct *	tty;
 	spinlock_t		lock;
-	struct semaphore        sem;
+	struct mutex            mutex;
 	unsigned char		number;
 
 	unsigned char *		interrupt_in_buffer;