USB: get rid of urb->lock

Now that urb->status isn't used, urb->lock doesn't protect anything.
This patch (as980) removes it and replaces it with a private mutex in
the one remaining place it was still used: usb_kill_urb.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/urb.c

@@ -39,7 +39,6 @@ void usb_init_urb(struct urb *urb)
 	if (urb) {
 		memset(urb, 0, sizeof(*urb));
 		kref_init(&urb->kref);
-		spin_lock_init(&urb->lock);
 		INIT_LIST_HEAD(&urb->anchor_list);
 	}
 }
@@ -541,19 +540,21 @@ int usb_unlink_urb(struct urb *urb)
  */
 void usb_kill_urb(struct urb *urb)
 {
+	static DEFINE_MUTEX(reject_mutex);
+
 	might_sleep();
 	if (!(urb && urb->dev && urb->ep))
 		return;
-	spin_lock_irq(&urb->lock);
+	mutex_lock(&reject_mutex);
 	++urb->reject;
-	spin_unlock_irq(&urb->lock);
+	mutex_unlock(&reject_mutex);
 
 	usb_hcd_unlink_urb(urb, -ENOENT);
 	wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
 
-	spin_lock_irq(&urb->lock);
+	mutex_lock(&reject_mutex);
 	--urb->reject;
-	spin_unlock_irq(&urb->lock);
+	mutex_unlock(&reject_mutex);
 }
 
 /**

include/linux/usb.h

@@ -1241,7 +1241,6 @@ struct urb
 {
 	/* private: usb core and host controller only fields in the urb */
 	struct kref kref;		/* reference count of the URB */
-	spinlock_t lock;		/* lock for the URB */
 	void *hcpriv;			/* private data for host controller */
 	atomic_t use_count;		/* concurrent submissions counter */
 	u8 reject;			/* submissions will fail */
@@ -1299,7 +1298,6 @@ static inline void usb_fill_control_urb (struct urb *urb,
 					 usb_complete_t complete_fn,
 					 void *context)
 {
-	spin_lock_init(&urb->lock);
 	urb->dev = dev;
 	urb->pipe = pipe;
 	urb->setup_packet = setup_packet;
@@ -1330,7 +1328,6 @@ static inline void usb_fill_bulk_urb (struct urb *urb,
 				      usb_complete_t complete_fn,
 				      void *context)
 {
-	spin_lock_init(&urb->lock);
 	urb->dev = dev;
 	urb->pipe = pipe;
 	urb->transfer_buffer = transfer_buffer;
@@ -1366,7 +1363,6 @@ static inline void usb_fill_int_urb (struct urb *urb,
 				     void *context,
 				     int interval)
 {
-	spin_lock_init(&urb->lock);
 	urb->dev = dev;
 	urb->pipe = pipe;
 	urb->transfer_buffer = transfer_buffer;