From: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
The musb_h_disable() routine can oops in some cases:
- It's not safe to read hep->hcpriv outside musb->lock,
since it gets changed on completion IRQ paths.
- The list iterators aren't safe to use in that way;
just remove the first element while !list_empty(),
so deletions on other code paths can't make trouble.
We need two "scrub the list" loops because only one branch
should touch hardware and advance the schedule.
[ dbrownell@xxxxxxxxxxxxxxxxxxxxx: massively simplify
patch description; add key points as code comments ]
Signed-off-by: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
---
BUGFIX: for 2.6.29-rc
drivers/usb/musb/musb_host.c | 36 ++++++++++++++++++++++++++----------
1 file changed, 26 insertions(+), 10 deletions(-)
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -2103,15 +2103,16 @@ musb_h_disable(struct usb_hcd *hcd, stru
unsigned long flags;
struct musb *musb = hcd_to_musb(hcd);
u8 is_in = epnum & USB_DIR_IN;
- struct musb_qh *qh = hep->hcpriv;
- struct urb *urb, *tmp;
+ struct musb_qh *qh;
+ struct urb *urb;
struct list_head *sched;
- if (!qh)
- return;
-
spin_lock_irqsave(&musb->lock, flags);
+ qh = hep->hcpriv;
+ if (qh == NULL)
+ goto exit;
+
switch (qh->type) {
case USB_ENDPOINT_XFER_CONTROL:
sched = &musb->control;
@@ -2145,13 +2146,28 @@ musb_h_disable(struct usb_hcd *hcd, stru
/* cleanup */
musb_cleanup_urb(urb, qh, urb->pipe & USB_DIR_IN);
- } else
- urb = NULL;
- /* then just nuke all the others */
- list_for_each_entry_safe_from(urb, tmp, &hep->urb_list, urb_list)
- musb_giveback(qh, urb, -ESHUTDOWN);
+ /* Then nuke all the others ... and advance the
+ * queue on hw_ep (e.g. bulk ring) when we're done.
+ */
+ while (!list_empty(&hep->urb_list)) {
+ urb = next_urb(qh);
+ urb->status = -ESHUTDOWN;
+ musb_advance_schedule(musb, urb, qh->hw_ep, is_in);
+ }
+ } else {
+ /* Just empty the queue; the hardware is busy with
+ * other transfers, and since !qh->is_ready nothing
+ * will activate any of these as it advances.
+ */
+ while (!list_empty(&hep->urb_list))
+ __musb_giveback(musb, next_urb(qh), -ESHUTDOWN);
+ hep->hcpriv = NULL;
+ list_del(&qh->ring);
+ kfree(qh);
+ }
+exit:
spin_unlock_irqrestore(&musb->lock, flags);
}
--
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