Re: [USB boot crash, -git] ecm_do_notify(), list_add corruption. prev->next should be next (ffff88003b8f82f8)

[David Brownell <david-b@pacbell.net>]

On Thursday 24 July 2008, Alan Stern wrote:
> Can you make the necessary change and try it out?

This resolves the problem for me ... and, I'd expect, for Ingo.


======= CUT HERE
From: David Brownell <dbrownell@users.sourceforge.net>

This fixes a BUG() turned up by Ingo via randconfig testing, where
CONFIG_LIST_DEBUG turned up list corruption.  The corruption was
caused by the dummy_hcd (single-machine test harness for gadget and
HCD code) trashing the request queue when driven by the new CDC
composite gadget an I/O pattern that was previously uncommon.
Fix suggested by Alan Stern.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
 drivers/usb/gadget/dummy_hcd.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/usb/gadget/dummy_hcd.c	2008-07-24 18:27:52.000000000 -0700
+++ b/drivers/usb/gadget/dummy_hcd.c	2008-07-26 07:35:12.000000000 -0700
@@ -542,13 +542,14 @@ dummy_queue (struct usb_ep *_ep, struct 
 		req->req.context = dum;
 		req->req.complete = fifo_complete;
 
+		list_add_tail(&req->queue, &ep->queue);
 		spin_unlock (&dum->lock);
 		_req->actual = _req->length;
 		_req->status = 0;
 		_req->complete (_ep, _req);
 		spin_lock (&dum->lock);
-	}
-	list_add_tail (&req->queue, &ep->queue);
+	}  else
+		list_add_tail(&req->queue, &ep->queue);
 	spin_unlock_irqrestore (&dum->lock, flags);
 
 	/* real hardware would likely enable transfers here, in case