[17/98] staging: usbip: Fix deadlock

[Greg KH]

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Eric Lescouet <lescouet@xxxxxxxxxxxxxxxx>

commit d01f42a22ef381ba973958e977209ac9a8667d57 upstream.

When detaching a port from the client side (usbip --detach 0),
the event thread, on the server side, is going to deadlock.
The "eh" server thread is getting USBIP_EH_RESET event and calls:
  -> stub_device_reset() -> usb_reset_device()
the USB framework is then calling back _in the same "eh" thread_ :
  -> stub_disconnect() -> usbip_stop_eh() -> wait_for_completion()
the "eh" thread is being asleep forever, waiting for its own completion.
This patch checks if "eh" is the current thread, in usbip_stop_eh().

Signed-off-by: Eric Lescouet <eric@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/staging/usbip/usbip_event.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/staging/usbip/usbip_event.c
+++ b/drivers/staging/usbip/usbip_event.c
@@ -117,6 +117,9 @@ void usbip_stop_eh(struct usbip_device *
 {
 	struct usbip_task *eh = &ud->eh;
 
+	if (eh->thread == current)
+		return; /* do not wait for myself */
+
 	wait_for_completion(&eh->thread_done);
 	usbip_dbg_eh("usbip_eh has finished\n");
 }


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