diff options
Diffstat (limited to 'drivers/usb/usb-skeleton.c')
| -rw-r--r-- | drivers/usb/usb-skeleton.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c index 962b28cd3a79..8432bf171d2e 100644 --- a/drivers/usb/usb-skeleton.c +++ b/drivers/usb/usb-skeleton.c @@ -34,6 +34,9 @@ static struct usb_device_id skel_table [] = { }; MODULE_DEVICE_TABLE(usb, skel_table); +/* to prevent a race between open and disconnect */ +static DEFINE_MUTEX(skel_open_lock); + /* Get a minor range for your devices from the usb maintainer */ #define USB_SKEL_MINOR_BASE 192 @@ -80,8 +83,10 @@ static int skel_open(struct inode *inode, struct file *file) subminor = iminor(inode); + mutex_lock(&skel_open_lock); interface = usb_find_interface(&skel_driver, subminor); if (!interface) { + mutex_unlock(&skel_open_lock); err ("%s - error, can't find device for minor %d", __FUNCTION__, subminor); retval = -ENODEV; @@ -90,12 +95,15 @@ static int skel_open(struct inode *inode, struct file *file) dev = usb_get_intfdata(interface); if (!dev) { + mutex_unlock(&skel_open_lock); retval = -ENODEV; goto exit; } /* increment our usage count for the device */ kref_get(&dev->kref); + /* now we can drop the lock */ + mutex_unlock(&skel_open_lock); /* prevent the device from being autosuspended */ retval = usb_autopm_get_interface(interface); @@ -361,14 +369,14 @@ static void skel_disconnect(struct usb_interface *interface) int minor = interface->minor; /* prevent skel_open() from racing skel_disconnect() */ - lock_kernel(); + mutex_lock(&skel_open_lock); dev = usb_get_intfdata(interface); usb_set_intfdata(interface, NULL); /* give back our minor */ usb_deregister_dev(interface, &skel_class); - unlock_kernel(); + mutex_unlock(&skel_open_lock); /* prevent more I/O from starting */ mutex_lock(&dev->io_mutex); |