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Subject[PATCH 4/5] use mutex instead of semaphore in the Adutux driver
The Adutux driver uses a semaphore as mutex. Use the mutex API
instead of the (binary) semaphore.

Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@gmail.com>

--

diff --git a/drivers/usb/misc/adutux.c b/drivers/usb/misc/adutux.c
index d72c42e..274d08e 100644
--- a/drivers/usb/misc/adutux.c
+++ b/drivers/usb/misc/adutux.c
@@ -24,6 +24,7 @@
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/usb.h>
+#include <linux/mutex.h>
#include <asm/uaccess.h>

#ifdef CONFIG_USB_DEBUG
@@ -80,7 +81,7 @@ MODULE_DEVICE_TABLE(usb, device_table);

/* Structure to hold all of our device specific stuff */
struct adu_device {
- struct semaphore sem; /* locks this structure */
+ struct mutex mtx; /* locks this structure */
struct usb_device* udev; /* save off the usb device pointer */
struct usb_interface* interface;
unsigned char minor; /* the starting minor number for this device */
@@ -269,8 +270,8 @@ static int adu_open(struct inode *inode, struct file *file)
}

/* lock this device */
- if ((retval = down_interruptible(&dev->sem))) {
- dbg(2, "%s : sem down failed", __FUNCTION__);
+ if ((retval = mutex_lock_interruptible(&dev->mtx))) {
+ dbg(2, "%s : mutex lock failed", __FUNCTION__);
goto exit_no_device;
}

@@ -299,7 +300,7 @@ static int adu_open(struct inode *inode, struct file *file)
if (retval)
--dev->open_count;
}
- up(&dev->sem);
+ mutex_unlock(&dev->mtx);

exit_no_device:
dbg(2,"%s : leave, return value %d ", __FUNCTION__, retval);
@@ -347,7 +348,7 @@ static int adu_release(struct inode *inode, struct file *file)
}

/* lock our device */
- down(&dev->sem); /* not interruptible */
+ mutex_lock(&dev->mtx); /* not interruptible */

if (dev->open_count <= 0) {
dbg(1," %s : device not opened", __FUNCTION__);
@@ -357,7 +358,7 @@ static int adu_release(struct inode *inode, struct file *file)

if (dev->udev == NULL) {
/* the device was unplugged before the file was released */
- up(&dev->sem);
+ mutex_unlock(&dev->mtx);
adu_delete(dev);
dev = NULL;
} else {
@@ -367,7 +368,7 @@ static int adu_release(struct inode *inode, struct file *file)

exit:
if (dev)
- up(&dev->sem);
+ mutex_unlock(&dev->mtx);
dbg(2," %s : leave, return value %d", __FUNCTION__, retval);
return retval;
}
@@ -390,7 +391,7 @@ static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
dev = file->private_data;
dbg(2," %s : dev=%p", __FUNCTION__, dev);
/* lock this object */
- if (down_interruptible(&dev->sem))
+ if (mutex_lock_interruptible(&dev->mtx))
return -ERESTARTSYS;

/* verify that the device wasn't unplugged */
@@ -522,7 +523,7 @@ static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,

exit:
/* unlock the device */
- up(&dev->sem);
+ mutex_unlock(&dev->mtx);

dbg(2," %s : leave, return value %d", __FUNCTION__, retval);
return retval;
@@ -543,7 +544,7 @@ static ssize_t adu_write(struct file *file, const __user char *buffer,
dev = file->private_data;

/* lock this object */
- retval = down_interruptible(&dev->sem);
+ retval = mutex_lock_interruptible(&dev->mtx);
if (retval)
goto exit_nolock;

@@ -571,9 +572,9 @@ static ssize_t adu_write(struct file *file, const __user char *buffer,
retval = -EINTR;
goto exit;
}
- up(&dev->sem);
+ mutex_unlock(&dev->mtx);
timeout = interruptible_sleep_on_timeout(&dev->write_wait, timeout);
- retval = down_interruptible(&dev->sem);
+ retval = mutex_lock_interruptible(&dev->mtx);
if (retval) {
retval = bytes_written ? bytes_written : retval;
goto exit_nolock;
@@ -638,7 +639,7 @@ static ssize_t adu_write(struct file *file, const __user char *buffer,

exit:
/* unlock the device */
- up(&dev->sem);
+ mutex_unlock(&dev->mtx);
exit_nolock:

dbg(2," %s : leave, return value %d", __FUNCTION__, retval);
@@ -698,7 +699,7 @@ static int adu_probe(struct usb_interface *interface,
goto exit;
}

- init_MUTEX(&dev->sem);
+ mutex_init(&dev->mtx);
spin_lock_init(&dev->buflock);
dev->udev = udev;
init_waitqueue_head(&dev->read_wait);
@@ -835,16 +836,16 @@ static void adu_disconnect(struct usb_interface *interface)
usb_deregister_dev(interface, &adu_class);
dev->minor = 0;

- down(&dev->sem); /* not interruptible */
+ mutex_lock(&dev->mtx); /* not interruptible */

/* if the device is not opened, then we clean up right now */
dbg(2," %s : open count %d", __FUNCTION__, dev->open_count);
if (!dev->open_count) {
- up(&dev->sem);
+ mutex_unlock(&dev->mtx);
adu_delete(dev);
} else {
dev->udev = NULL;
- up(&dev->sem);
+ mutex_unlock(&dev->mtx);
}

dev_info(&interface->dev, "ADU device adutux%d now disconnected",
--
Matthias Kaehlcke
Linux Application Developer
Barcelona

The assumption that what currently exists must necessarily
exist is the acid that corrodes all visionary thinking
.''`.
using free software / Debian GNU/Linux | http://debian.org : :' :
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