1 files changed, 37 insertions, 14 deletions

diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
index 6fb5140e29b9..45cff32656c6 100644
--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -27,6 +27,8 @@ static struct usb_class_driver chaoskey_class;
 static int chaoskey_rng_read(struct hwrng *rng, void *data,
 			     size_t max, bool wait);
 
+static DEFINE_MUTEX(chaoskey_list_lock);
+
 #define usb_dbg(usb_if, format, arg...) \
 	dev_dbg(&(usb_if)->dev, format, ## arg)
 
@@ -233,6 +235,7 @@ static void chaoskey_disconnect(struct usb_interface *interface)
 	usb_deregister_dev(interface, &chaoskey_class);
 
 	usb_set_intfdata(interface, NULL);
+	mutex_lock(&chaoskey_list_lock);
 	mutex_lock(&dev->lock);
 
 	dev->present = false;
@@ -244,6 +247,7 @@ static void chaoskey_disconnect(struct usb_interface *interface)
 	} else
 		mutex_unlock(&dev->lock);
 
+	mutex_unlock(&chaoskey_list_lock);
 	usb_dbg(interface, "disconnect done");
 }
 
@@ -251,6 +255,7 @@ static int chaoskey_open(struct inode *inode, struct file *file)
 {
 	struct chaoskey *dev;
 	struct usb_interface *interface;
+	int rv = 0;
 
 	/* get the interface from minor number and driver information */
 	interface = usb_find_interface(&chaoskey_driver, iminor(inode));
@@ -266,18 +271,23 @@ static int chaoskey_open(struct inode *inode, struct file *file)
 	}
 
 	file->private_data = dev;
+	mutex_lock(&chaoskey_list_lock);
 	mutex_lock(&dev->lock);
-	++dev->open;
+	if (dev->present)
+		++dev->open;
+	else
+		rv = -ENODEV;
 	mutex_unlock(&dev->lock);
+	mutex_unlock(&chaoskey_list_lock);
 
-	usb_dbg(interface, "open success");
-	return 0;
+	return rv;
 }
 
 static int chaoskey_release(struct inode *inode, struct file *file)
 {
 	struct chaoskey *dev = file->private_data;
 	struct usb_interface *interface;
+	int rv = 0;
 
 	if (dev == NULL)
 		return -ENODEV;
@@ -286,14 +296,15 @@ static int chaoskey_release(struct inode *inode, struct file *file)
 
 	usb_dbg(interface, "release");
 
+	mutex_lock(&chaoskey_list_lock);
 	mutex_lock(&dev->lock);
 
 	usb_dbg(interface, "open count at release is %d", dev->open);
 
 	if (dev->open <= 0) {
 		usb_dbg(interface, "invalid open count (%d)", dev->open);
-		mutex_unlock(&dev->lock);
-		return -ENODEV;
+		rv = -ENODEV;
+		goto bail;
 	}
 
 	--dev->open;
@@ -302,13 +313,15 @@ static int chaoskey_release(struct inode *inode, struct file *file)
 		if (dev->open == 0) {
 			mutex_unlock(&dev->lock);
 			chaoskey_free(dev);
-		} else
-			mutex_unlock(&dev->lock);
-	} else
-		mutex_unlock(&dev->lock);
-
+			goto destruction;
+		}
+	}
+bail:
+	mutex_unlock(&dev->lock);
+destruction:
+	mutex_unlock(&chaoskey_list_lock);
 	usb_dbg(interface, "release success");
-	return 0;
+	return rv;
 }
 
 static void chaos_read_callback(struct urb *urb)
@@ -431,9 +444,19 @@ static ssize_t chaoskey_read(struct file *file,
 			goto bail;
 		mutex_unlock(&dev->rng_lock);
 
-		result = mutex_lock_interruptible(&dev->lock);
-		if (result)
-			goto bail;
+		if (file->f_flags & O_NONBLOCK) {
+			result = mutex_trylock(&dev->lock);
+			if (result == 0) {
+				result = -EAGAIN;
+				goto bail;
+			} else {
+				result = 0;
+			}
+		} else {
+			result = mutex_lock_interruptible(&dev->lock);
+			if (result)
+				goto bail;
+		}
 		if (dev->valid == dev->used) {
 			result = _chaoskey_fill(dev);
 			if (result < 0) {