usb: gadget: f_midi: missing unlock on error path

We added a new error path to this function and we forgot to drop the
lock.

Fixes: e1e3d7ec ('usb: gadget: f_midi: pre-allocate IN requests')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
[mina86@mina86.com: rebased on top of refactoring commit]
Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/gadget/function/f_midi.c

@@ -1157,7 +1157,7 @@ static void f_midi_unbind(struct usb_configuration *c, struct usb_function *f)
 
 static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
 {
-	struct f_midi *midi;
+	struct f_midi *midi = NULL;
 	struct f_midi_opts *opts;
 	int status, i;
 
@@ -1166,8 +1166,8 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
 	mutex_lock(&opts->lock);
 	/* sanity check */
 	if (opts->in_ports > MAX_PORTS || opts->out_ports > MAX_PORTS) {
-		mutex_unlock(&opts->lock);
-		return ERR_PTR(-EINVAL);
+		status = -EINVAL;
+		goto setup_fail;
 	}
 
 	/* allocate and initialize one new instance */
@@ -1175,8 +1175,8 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
 		sizeof(*midi) + opts->in_ports * sizeof(*midi->in_ports_array),
 		GFP_KERNEL);
 	if (!midi) {
-		mutex_unlock(&opts->lock);
-		return ERR_PTR(-ENOMEM);
+		status = -ENOMEM;
+		goto setup_fail;
 	}
 
 	for (i = 0; i < opts->in_ports; i++)
@@ -1186,7 +1186,6 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
 	midi->id = kstrdup(opts->id, GFP_KERNEL);
 	if (opts->id && !midi->id) {
 		status = -ENOMEM;
-		mutex_unlock(&opts->lock);
 		goto setup_fail;
 	}
 	midi->in_ports = opts->in_ports;
@@ -1213,6 +1212,7 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
 	return &midi->func;
 
 setup_fail:
+	mutex_unlock(&opts->lock);
 	kfree(midi);
 	return ERR_PTR(status);
 }