staging: usbip: use interrupt safe spinlock to avoid potential deadlock.

The function 'usbip_event_add()' may be called in interrupt context on
the stub side:
'stub_complete'->'stub_enqueue_ret_unlink'->'usbip_event_add'.
In this function it tries to get the lock 'ud->lock', so we should
disable irq when we get this lock in process context.

Signed-off-by: Harvey Yang <harvey.huawei.yang@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/staging/usbip/usbip_event.c b/drivers/staging/usbip/usbip_event.c
index d332a34ddb6..82123be8732 100644
--- a/drivers/staging/usbip/usbip_event.c
+++ b/drivers/staging/usbip/usbip_event.c
@@ -105,10 +105,12 @@ EXPORT_SYMBOL_GPL(usbip_stop_eh);
 
 void usbip_event_add(struct usbip_device *ud, unsigned long event)
 {
-	spin_lock(&ud->lock);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ud->lock, flags);
 	ud->event |= event;
 	wake_up(&ud->eh_waitq);
-	spin_unlock(&ud->lock);
+	spin_unlock_irqrestore(&ud->lock, flags);
 }
 EXPORT_SYMBOL_GPL(usbip_event_add);