USB: fix cdc-acm problems with hard irq? (inconsistent lock state)

Signed-off-by: Jarek Poplawski <jarkao2@o2.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/class/cdc-acm.c

@@ -325,7 +325,7 @@ static void acm_rx_tasklet(unsigned long _acm)
 	struct acm_rb *buf;
 	struct tty_struct *tty = acm->tty;
 	struct acm_ru *rcv;
-	//unsigned long flags;
+	unsigned long flags;
 	int i = 0;
 	dbg("Entering acm_rx_tasklet");
 
@@ -333,15 +333,15 @@ static void acm_rx_tasklet(unsigned long _acm)
 		return;
 
 next_buffer:
-	spin_lock(&acm->read_lock);
+	spin_lock_irqsave(&acm->read_lock, flags);
 	if (list_empty(&acm->filled_read_bufs)) {
-		spin_unlock(&acm->read_lock);
+		spin_unlock_irqrestore(&acm->read_lock, flags);
 		goto urbs;
 	}
 	buf = list_entry(acm->filled_read_bufs.next,
 			 struct acm_rb, list);
 	list_del(&buf->list);
-	spin_unlock(&acm->read_lock);
+	spin_unlock_irqrestore(&acm->read_lock, flags);
 
 	dbg("acm_rx_tasklet: procesing buf 0x%p, size = %d", buf, buf->size);
 
@@ -356,29 +356,29 @@ next_buffer:
 		memmove(buf->base, buf->base + i, buf->size - i);
 		buf->size -= i;
 		spin_unlock(&acm->throttle_lock);
-		spin_lock(&acm->read_lock);
+		spin_lock_irqsave(&acm->read_lock, flags);
 		list_add(&buf->list, &acm->filled_read_bufs);
-		spin_unlock(&acm->read_lock);
+		spin_unlock_irqrestore(&acm->read_lock, flags);
 		return;
 	}
 	spin_unlock(&acm->throttle_lock);
 
-	spin_lock(&acm->read_lock);
+	spin_lock_irqsave(&acm->read_lock, flags);
 	list_add(&buf->list, &acm->spare_read_bufs);
-	spin_unlock(&acm->read_lock);
+	spin_unlock_irqrestore(&acm->read_lock, flags);
 	goto next_buffer;
 
 urbs:
 	while (!list_empty(&acm->spare_read_bufs)) {
-		spin_lock(&acm->read_lock);
+		spin_lock_irqsave(&acm->read_lock, flags);
 		if (list_empty(&acm->spare_read_urbs)) {
-			spin_unlock(&acm->read_lock);
+			spin_unlock_irqrestore(&acm->read_lock, flags);
 			return;
 		}
 		rcv = list_entry(acm->spare_read_urbs.next,
 				 struct acm_ru, list);
 		list_del(&rcv->list);
-		spin_unlock(&acm->read_lock);
+		spin_unlock_irqrestore(&acm->read_lock, flags);
 
 		buf = list_entry(acm->spare_read_bufs.next,
 				 struct acm_rb, list);
@@ -400,9 +400,9 @@ urbs:
 		   free-urbs-pool and resubmited ASAP */
 		if (usb_submit_urb(rcv->urb, GFP_ATOMIC) < 0) {
 			list_add(&buf->list, &acm->spare_read_bufs);
-			spin_lock(&acm->read_lock);
+			spin_lock_irqsave(&acm->read_lock, flags);
 			list_add(&rcv->list, &acm->spare_read_urbs);
-			spin_unlock(&acm->read_lock);
+			spin_unlock_irqrestore(&acm->read_lock, flags);
 			return;
 		}
 	}