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path: root/drivers/usb/misc/usblcd.c
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Diffstat (limited to 'drivers/usb/misc/usblcd.c')
-rw-r--r--drivers/usb/misc/usblcd.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/usb/misc/usblcd.c b/drivers/usb/misc/usblcd.c
index 71984203271..20777d01db6 100644
--- a/drivers/usb/misc/usblcd.c
+++ b/drivers/usb/misc/usblcd.c
@@ -17,6 +17,7 @@
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/errno.h>
+#include <linux/mutex.h>
#include <asm/uaccess.h>
#include <linux/usb.h>
@@ -34,6 +35,8 @@ static struct usb_device_id id_table [] = {
};
MODULE_DEVICE_TABLE (usb, id_table);
+static DEFINE_MUTEX(open_disc_mutex);
+
struct usb_lcd {
struct usb_device * udev; /* init: probe_lcd */
@@ -79,12 +82,16 @@ static int lcd_open(struct inode *inode, struct file *file)
return -ENODEV;
}
+ mutex_lock(&open_disc_mutex);
dev = usb_get_intfdata(interface);
- if (!dev)
+ if (!dev) {
+ mutex_unlock(&open_disc_mutex);
return -ENODEV;
+ }
/* increment our usage count for the device */
kref_get(&dev->kref);
+ mutex_unlock(&open_disc_mutex);
/* grab a power reference */
r = usb_autopm_get_interface(interface);
@@ -393,8 +400,10 @@ static void lcd_disconnect(struct usb_interface *interface)
struct usb_lcd *dev;
int minor = interface->minor;
+ mutex_lock(&open_disc_mutex);
dev = usb_get_intfdata(interface);
usb_set_intfdata(interface, NULL);
+ mutex_unlock(&open_disc_mutex);
/* give back our minor */
usb_deregister_dev(interface, &lcd_class);