diff options
Diffstat (limited to 'drivers/usb/misc/usblcd.c')
| -rw-r--r-- | drivers/usb/misc/usblcd.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/usb/misc/usblcd.c b/drivers/usb/misc/usblcd.c index 7198420..20777d0 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); |