USB: usblcd: drop redundant lcd mutex

Drop the redundant lcd mutex introduced by commit 925ce689bb31 ("USB:
autoconvert trivial BKL users to private mutex") which replaced an
earlier BKL use.

The lock serialised calls to open() against other open() and a custom
ioctl() returning the bcdDevice (sic!), but neither is needed.

Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20190926091228.24634-9-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/misc/usblcd.c b/drivers/usb/misc/usblcd.c
index b898650..732eb1f 100644 (file)
--- a/drivers/usb/misc/usblcd.c
+++ b/drivers/usb/misc/usblcd.c
@@ -30,7 +30,6 @@
 #define IOCTL_GET_DRV_VERSION  2
 
 
-static DEFINE_MUTEX(lcd_mutex);
 static const struct usb_device_id id_table[] = {
        { .idVendor = 0x10D2, .match_flags = USB_DEVICE_ID_MATCH_VENDOR, },
        { },
@@ -81,12 +80,10 @@ static int lcd_open(struct inode *inode, struct file *file)
        struct usb_interface *interface;
        int subminor, r;
 
-       mutex_lock(&lcd_mutex);
        subminor = iminor(inode);
 
        interface = usb_find_interface(&lcd_driver, subminor);
        if (!interface) {
-               mutex_unlock(&lcd_mutex);
                printk(KERN_ERR "USBLCD: %s - error, can't find device for minor %d\n",
                       __func__, subminor);
                return -ENODEV;
@@ -101,13 +98,11 @@ static int lcd_open(struct inode *inode, struct file *file)
        r = usb_autopm_get_interface(interface);
        if (r < 0) {
                kref_put(&dev->kref, lcd_delete);
-               mutex_unlock(&lcd_mutex);
                return r;
        }
 
        /* save our object in the file's private structure */
        file->private_data = dev;
-       mutex_unlock(&lcd_mutex);
 
        return 0;
 }
@@ -176,14 +171,12 @@ static long lcd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
        switch (cmd) {
        case IOCTL_GET_HARD_VERSION:
-               mutex_lock(&lcd_mutex);
                bcdDevice = le16_to_cpu((dev->udev)->descriptor.bcdDevice);
                sprintf(buf, "%1d%1d.%1d%1d",
                        (bcdDevice & 0xF000)>>12,
                        (bcdDevice & 0xF00)>>8,
                        (bcdDevice & 0xF0)>>4,
                        (bcdDevice & 0xF));
-               mutex_unlock(&lcd_mutex);
                if (copy_to_user((void __user *)arg, buf, strlen(buf)) != 0)
                        return -EFAULT;
                break;