staging: usbip: Fix deadlock

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@lescouet.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/staging/usbip/usbip_event.c b/drivers/staging/usbip/usbip_event.c
index 6da1021e8a65edd1d9baad721ae3d50bc58f78da..a2566f1075d557014e4bcd443fb02ed36202dc72 100644 (file)
--- 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 *ud)
 {
        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");
 }