[PATCH 2/5] use mutex instead of semaphore in the USB gadget serial driver

From: Matthias Kaehlcke
Date: Fri Jul 13 2007 - 15:24:21 EST


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@xxxxxxxxx>

--

diff --git a/drivers/usb/gadget/serial.c b/drivers/usb/gadget/serial.c
index dd33ff0..4192d24 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);
}

/*

--
Matthias Kaehlcke
Linux Application Developer
Barcelona

If liberty means anything at all, it means the
right to tell people what they do not want to hear
(George Orwell)
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