Input: synaptics_usb - fix deadlock in autosuspend

usb_autopm_get_interface() that is called in synusb_open() does an
autoresume if the device is suspended.

input_dev->mutex used in synusb_resume() is in this case already
taken by the input subsystem and will cause a deadlock.
Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/synaptics_usb.c

@@ -82,6 +82,9 @@ struct synusb {
 	struct urb *urb;
 	unsigned char *data;
 
+	/* serialize access to open/suspend */
+	struct mutex pm_mutex;
+
 	/* input device related data structures */
 	struct input_dev *input;
 	char name[128];
@@ -252,6 +255,7 @@ static int synusb_open(struct input_dev *dev)
 		return retval;
 	}
 
+	mutex_lock(&synusb->pm_mutex);
 	retval = usb_submit_urb(synusb->urb, GFP_KERNEL);
 	if (retval) {
 		dev_err(&synusb->intf->dev,
@@ -264,6 +268,7 @@ static int synusb_open(struct input_dev *dev)
 	synusb->intf->needs_remote_wakeup = 1;
 
 out:
+	mutex_unlock(&synusb->pm_mutex);
 	usb_autopm_put_interface(synusb->intf);
 	return retval;
 }
@@ -275,8 +280,10 @@ static void synusb_close(struct input_dev *dev)
 
 	autopm_error = usb_autopm_get_interface(synusb->intf);
 
+	mutex_lock(&synusb->pm_mutex);
 	usb_kill_urb(synusb->urb);
 	synusb->intf->needs_remote_wakeup = 0;
+	mutex_unlock(&synusb->pm_mutex);
 
 	if (!autopm_error)
 		usb_autopm_put_interface(synusb->intf);
@@ -315,6 +322,7 @@ static int synusb_probe(struct usb_interface *intf,
 	synusb->udev = udev;
 	synusb->intf = intf;
 	synusb->input = input_dev;
+	mutex_init(&synusb->pm_mutex);
 
 	synusb->flags = id->driver_info;
 	if (synusb->flags & SYNUSB_COMBO) {
@@ -466,11 +474,10 @@ static void synusb_disconnect(struct usb_interface *intf)
 static int synusb_suspend(struct usb_interface *intf, pm_message_t message)
 {
 	struct synusb *synusb = usb_get_intfdata(intf);
-	struct input_dev *input_dev = synusb->input;
 
-	mutex_lock(&input_dev->mutex);
+	mutex_lock(&synusb->pm_mutex);
 	usb_kill_urb(synusb->urb);
-	mutex_unlock(&input_dev->mutex);
+	mutex_unlock(&synusb->pm_mutex);
 
 	return 0;
 }
@@ -481,14 +488,14 @@ static int synusb_resume(struct usb_interface *intf)
 	struct input_dev *input_dev = synusb->input;
 	int retval = 0;
 
-	mutex_lock(&input_dev->mutex);
+	mutex_lock(&synusb->pm_mutex);
 
 	if ((input_dev->users || (synusb->flags & SYNUSB_IO_ALWAYS)) &&
 	    usb_submit_urb(synusb->urb, GFP_NOIO) < 0) {
 		retval = -EIO;
 	}
 
-	mutex_unlock(&input_dev->mutex);
+	mutex_unlock(&synusb->pm_mutex);
 
 	return retval;
 }
@@ -496,9 +503,8 @@ static int synusb_resume(struct usb_interface *intf)
 static int synusb_pre_reset(struct usb_interface *intf)
 {
 	struct synusb *synusb = usb_get_intfdata(intf);
-	struct input_dev *input_dev = synusb->input;
 
-	mutex_lock(&input_dev->mutex);
+	mutex_lock(&synusb->pm_mutex);
 	usb_kill_urb(synusb->urb);
 
 	return 0;
@@ -515,7 +521,7 @@ static int synusb_post_reset(struct usb_interface *intf)
 		retval = -EIO;
 	}
 
-	mutex_unlock(&input_dev->mutex);
+	mutex_unlock(&synusb->pm_mutex);
 
 	return retval;
 }