1 files changed, 24 insertions, 14 deletions

diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c
index ba5d6d927a49..791a26bd5f63 100644
--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -38,6 +38,7 @@
 #include "comedi_internal.h"
 
 struct comedi_driver *comedi_drivers;
+DEFINE_MUTEX(comedi_drivers_list_lock);
 
 int comedi_set_hw_dev(struct comedi_device *dev, struct device *hw_dev)
 {
@@ -453,6 +454,7 @@ int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	if (dev->attached)
 		return -EBUSY;
 
+	mutex_lock(&comedi_drivers_list_lock);
 	for (driv = comedi_drivers; driv; driv = driv->next) {
 		if (!try_module_get(driv->module))
 			continue;
@@ -473,7 +475,8 @@ int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 			comedi_report_boards(driv);
 			module_put(driv->module);
 		}
-		return -EIO;
+		ret = -EIO;
+		goto out;
 	}
 	if (driv->attach == NULL) {
 		/* driver does not support manual configuration */
@@ -481,7 +484,8 @@ int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 			 "driver '%s' does not support attach using comedi_config\n",
 			 driv->driver_name);
 		module_put(driv->module);
-		return -ENOSYS;
+		ret = -ENOSYS;
+		goto out;
 	}
 	/* initialize dev->driver here so
 	 * comedi_error() can be called from attach */
@@ -496,6 +500,8 @@ int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 		module_put(dev->driver->module);
 	}
 	/* On success, the driver module count has been incremented. */
+out:
+	mutex_unlock(&comedi_drivers_list_lock);
 	return ret;
 }
 
@@ -552,8 +558,10 @@ EXPORT_SYMBOL_GPL(comedi_auto_unconfig);
 
 int comedi_driver_register(struct comedi_driver *driver)
 {
+	mutex_lock(&comedi_drivers_list_lock);
 	driver->next = comedi_drivers;
 	comedi_drivers = driver;
+	mutex_unlock(&comedi_drivers_list_lock);
 
 	return 0;
 }
@@ -564,6 +572,20 @@ void comedi_driver_unregister(struct comedi_driver *driver)
 	struct comedi_driver *prev;
 	int i;
 
+	/* unlink the driver */
+	mutex_lock(&comedi_drivers_list_lock);
+	if (comedi_drivers == driver) {
+		comedi_drivers = driver->next;
+	} else {
+		for (prev = comedi_drivers; prev->next; prev = prev->next) {
+			if (prev->next == driver) {
+				prev->next = driver->next;
+				break;
+			}
+		}
+	}
+	mutex_unlock(&comedi_drivers_list_lock);
+
 	/* check for devices using this driver */
 	for (i = 0; i < COMEDI_NUM_BOARD_MINORS; i++) {
 		struct comedi_device *dev = comedi_dev_from_minor(i);
@@ -581,17 +603,5 @@ void comedi_driver_unregister(struct comedi_driver *driver)
 		}
 		mutex_unlock(&dev->mutex);
 	}
-
-	if (comedi_drivers == driver) {
-		comedi_drivers = driver->next;
-		return;
-	}
-
-	for (prev = comedi_drivers; prev->next; prev = prev->next) {
-		if (prev->next == driver) {
-			prev->next = driver->next;
-			return;
-		}
-	}
 }
 EXPORT_SYMBOL_GPL(comedi_driver_unregister);