USB: iowarrior: drop redundant disconnect mutex

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@kernel.org>
Link: https://lore.kernel.org/r/20191009104846.5925-5-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/misc/iowarrior.c b/drivers/usb/misc/iowarrior.c
index f405fa734bcc3efd15b48fc5622e928dfe46b674..d844c2098e42e30683329631401629fb6c02f6f7 100644 (file)
--- a/drivers/usb/misc/iowarrior.c
+++ b/drivers/usb/misc/iowarrior.c
@@ -58,7 +58,6 @@ MODULE_LICENSE("GPL");
 static DEFINE_MUTEX(iowarrior_mutex);
 
 static struct usb_driver iowarrior_driver;
-static DEFINE_MUTEX(iowarrior_open_disc_lock);
 
 /*--------------*/
 /*     data     */
@@ -601,16 +600,13 @@ static int iowarrior_open(struct inode *inode, struct file *file)
                return -ENODEV;
        }
 
-       mutex_lock(&iowarrior_open_disc_lock);
        dev = usb_get_intfdata(interface);
        if (!dev) {
-               mutex_unlock(&iowarrior_open_disc_lock);
                mutex_unlock(&iowarrior_mutex);
                return -ENODEV;
        }
 
        mutex_lock(&dev->mutex);
-       mutex_unlock(&iowarrior_open_disc_lock);
 
        /* Only one process can open each device, no sharing. */
        if (dev->opened) {
@@ -842,7 +838,6 @@ static int iowarrior_probe(struct usb_interface *interface,
        if (retval) {
                /* 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;
        }
 
@@ -866,16 +861,8 @@ error:
  */
 static void iowarrior_disconnect(struct usb_interface *interface)
 {
-       struct iowarrior *dev;
-       int minor;
-
-       dev = usb_get_intfdata(interface);
-       mutex_lock(&iowarrior_open_disc_lock);
-       usb_set_intfdata(interface, NULL);
-
-       minor = dev->minor;
-       mutex_unlock(&iowarrior_open_disc_lock);
-       /* give back our minor - this will call close() locks need to be dropped at this point*/
+       struct iowarrior *dev = usb_get_intfdata(interface);
+       int minor = dev->minor;
 
        usb_deregister_dev(interface, &iowarrior_class);