Drop the redundant disconnect mutex which was introduced after the
open-disconnect race had been addressed generally in USB core by commit
d4ead16f50f9 ("USB: prevent char device open/deregister race").
Specifically, the rw-semaphore in core guarantees that all calls to
open() will have completed and that no new calls to open() will occur
after usb_deregister_dev() returns. Hence there is no need use the
driver data as an inverted disconnected flag.
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
drivers/usb/misc/usblcd.c | 18 +-----------------
1 file changed, 1 insertion(+), 17 deletions(-)
diff --git a/drivers/usb/misc/usblcd.c b/drivers/usb/misc/usblcd.c
index aa982d3ca36b..b898650a5570 100644
--- a/drivers/usb/misc/usblcd.c
+++ b/drivers/usb/misc/usblcd.c
@@ -37,9 +37,6 @@ static const 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 */
struct usb_interface *interface; /* the interface for
@@ -95,17 +92,10 @@ static int lcd_open(struct inode *inode, struct file *file)
return -ENODEV;
}
- mutex_lock(&open_disc_mutex);
dev = usb_get_intfdata(interface);
- if (!dev) {
- mutex_unlock(&open_disc_mutex);
- mutex_unlock(&lcd_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);
@@ -388,7 +378,6 @@ static int lcd_probe(struct usb_interface *interface,
/* something prevented us from registering this driver */
dev_err(&interface->dev,
"Not able to get a minor for this device.\n");
- usb_set_intfdata(interface, NULL);
goto error;
}
@@ -434,14 +423,9 @@ static int lcd_resume(struct usb_interface *intf)
static void lcd_disconnect(struct usb_interface *interface)
{
- struct usb_lcd *dev;
+ struct usb_lcd *dev = usb_get_intfdata(interface);
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);
--
2.23.0
