USB: fix locking in idmouse

Pete caused me to lock at buggy drivers in this respect. The idmouse has
a race between open and disconnect. This patch

- solves the open/disconnect race
- switches locking to mutexes

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/misc/idmouse.c b/drivers/usb/misc/idmouse.c
index e6fd024024f50c1c317bba53328cd553bef7dd7b..4bcf7fb4e5da7c06c54021631f6f39a1a098fd06 100644 (file)
--- a/drivers/usb/misc/idmouse.c
+++ b/drivers/usb/misc/idmouse.c
@@ -66,6 +66,7 @@ static struct usb_device_id idmouse_table[] = {
        USB_TYPE_VENDOR | USB_RECIP_ENDPOINT | USB_DIR_OUT, value, index, NULL, 0, 1000)
 
 MODULE_DEVICE_TABLE(usb, idmouse_table);
+static DEFINE_MUTEX(open_disc_mutex);
 
 /* structure to hold all of our device specific stuff */
 struct usb_idmouse {
@@ -80,7 +81,7 @@ struct usb_idmouse {
 
        int open; /* if the port is open or not */
        int present; /* if the device is not disconnected */
-       struct semaphore sem; /* locks this structure */
+       struct mutex lock; /* locks this structure */
 
 };
 
@@ -213,13 +214,17 @@ static int idmouse_open(struct inode *inode, struct file *file)
        if (!interface)
                return -ENODEV;
 
+       mutex_lock(&open_disc_mutex);
        /* get the device information block from the interface */
        dev = usb_get_intfdata(interface);
-       if (!dev)
+       if (!dev) {
+               mutex_unlock(&open_disc_mutex);
                return -ENODEV;
+       }
 
        /* lock this device */
-       down(&dev->sem);
+       mutex_lock(&dev->lock);
+       mutex_unlock(&open_disc_mutex);
 
        /* check if already open */
        if (dev->open) {
@@ -245,7 +250,7 @@ static int idmouse_open(struct inode *inode, struct file *file)
 error:
 
        /* unlock this device */
-       up(&dev->sem);
+       mutex_unlock(&dev->lock);
        return result;
 }
 
@@ -258,12 +263,14 @@ static int idmouse_release(struct inode *inode, struct file *file)
        if (dev == NULL)
                return -ENODEV;
 
+       mutex_lock(&open_disc_mutex);
        /* lock our device */
-       down(&dev->sem);
+       mutex_lock(&dev->lock);
 
        /* are we really open? */
        if (dev->open <= 0) {
-               up(&dev->sem);
+               mutex_unlock(&dev->lock);
+               mutex_unlock(&open_disc_mutex);
                return -ENODEV;
        }
 
@@ -271,10 +278,12 @@ static int idmouse_release(struct inode *inode, struct file *file)
 
        if (!dev->present) {
                /* the device was unplugged before the file was released */
-               up(&dev->sem);
+               mutex_unlock(&dev->lock);
+               mutex_unlock(&open_disc_mutex);
                idmouse_delete(dev);
        } else {
-               up(&dev->sem);
+               mutex_unlock(&dev->lock);
+               mutex_unlock(&open_disc_mutex);
        }
        return 0;
 }
@@ -286,18 +295,18 @@ static ssize_t idmouse_read(struct file *file, char __user *buffer, size_t count
        int result;
 
        /* lock this object */
-       down(&dev->sem);
+       mutex_lock(&dev->lock);
 
        /* verify that the device wasn't unplugged */
        if (!dev->present) {
-               up(&dev->sem);
+               mutex_unlock(&dev->lock);
                return -ENODEV;
        }
 
        result = simple_read_from_buffer(buffer, count, ppos,
                                        dev->bulk_in_buffer, IMGSIZE);
        /* unlock the device */
-       up(&dev->sem);
+       mutex_unlock(&dev->lock);
        return result;
 }
 
@@ -320,7 +329,7 @@ static int idmouse_probe(struct usb_interface *interface,
        if (dev == NULL)
                return -ENOMEM;
 
-       init_MUTEX(&dev->sem);
+       mutex_init(&dev->lock);
        dev->udev = udev;
        dev->interface = interface;
 
@@ -372,24 +381,26 @@ static void idmouse_disconnect(struct usb_interface *interface)
 
        /* get device structure */
        dev = usb_get_intfdata(interface);
-       usb_set_intfdata(interface, NULL);
 
        /* give back our minor */
        usb_deregister_dev(interface, &idmouse_class);
 
-       /* lock it */
-       down(&dev->sem);
+       mutex_lock(&open_disc_mutex);
+       usb_set_intfdata(interface, NULL);
+       /* lock the device */
+       mutex_lock(&dev->lock);
+       mutex_unlock(&open_disc_mutex);
 
        /* prevent device read, write and ioctl */
        dev->present = 0;
 
        /* if the device is opened, idmouse_release will clean this up */
        if (!dev->open) {
-               up(&dev->sem);
+               mutex_unlock(&dev->lock);
                idmouse_delete(dev);
        } else {
                /* unlock */
-               up(&dev->sem);
+               mutex_unlock(&dev->lock);
        }
 
        info("%s disconnected", DRIVER_DESC);