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Subject[022/117] staging: usbip: Fix deadlock
2.6.33-stable review patch.  If anyone has any objections, please let us know.

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

From: Eric Lescouet <lescouet@virtuallogix.com>

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>

---
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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