[PATCH] [154/275] xhci: Avoid BUG() in interrupt context

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Paul Zimmerman <Paul.Zimmerman@xxxxxxxxxxxx>

commit 68e41c5d032668e2905404afbef75bc58be179d6 upstream.

Change the BUGs in xhci_find_new_dequeue_state() to WARN_ONs, to avoid
bringing down the box if one of them is hit

This patch should be queued for stable kernels back to 2.6.31.

Signed-off-by: Paul Zimmerman <paulz@xxxxxxxxxxxx>
Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
 drivers/usb/host/xhci-ring.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

Index: linux-2.6.35.y/drivers/usb/host/xhci-ring.c
===================================================================
--- linux-2.6.35.y.orig/drivers/usb/host/xhci-ring.c	2011-03-29 22:51:04.398610620 -0700
+++ linux-2.6.35.y/drivers/usb/host/xhci-ring.c	2011-03-29 23:54:35.235100848 -0700
@@ -457,8 +457,11 @@
 	state->new_deq_seg = find_trb_seg(cur_td->start_seg,
 			dev->eps[ep_index].stopped_trb,
 			&state->new_cycle_state);
-	if (!state->new_deq_seg)
-		BUG();
+	if (!state->new_deq_seg) {
+		WARN_ON(1);
+		return;
+	}
+
 	/* Dig out the cycle state saved by the xHC during the stop ep cmd */
 	xhci_dbg(xhci, "Finding endpoint context\n");
 	ep_ctx = xhci_get_ep_ctx(xhci, dev->out_ctx, ep_index);
@@ -469,8 +472,10 @@
 	state->new_deq_seg = find_trb_seg(state->new_deq_seg,
 			state->new_deq_ptr,
 			&state->new_cycle_state);
-	if (!state->new_deq_seg)
-		BUG();
+	if (!state->new_deq_seg) {
+		WARN_ON(1);
+		return;
+	}
 
 	trb = &state->new_deq_ptr->generic;
 	if ((trb->field[3] & TRB_TYPE_BITMASK) == TRB_TYPE(TRB_LINK) &&
--
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