This is a note to let you know that I've just added the patch titled
USB: OHCI: don't lose track of EDs when a controller dies
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From 977dcfdc60311e7aa571cabf6f39c36dde13339e Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 17 Jul 2014 16:34:29 -0400
Subject: USB: OHCI: don't lose track of EDs when a controller dies
This patch fixes a bug in ohci-hcd. When an URB is unlinked, the
corresponding Endpoint Descriptor is added to the ed_rm_list and taken
off the hardware schedule. Once the ED is no longer visible to the
hardware, finish_unlinks() handles the URBs that were unlinked or have
completed. If any URBs remain attached to the ED, the ED is added
back to the hardware schedule -- but only if the controller is
running.
This fails when a controller dies. A non-empty ED does not get added
back to the hardware schedule and does not remain on the ed_rm_list;
ohci-hcd loses track of it. The remaining URBs cannot be unlinked,
which causes the USB stack to hang.
The patch changes finish_unlinks() so that non-empty EDs remain on
the ed_rm_list if the controller isn't running. This requires moving
some of the existing code around, to avoid modifying the ED's hardware
fields more than once.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
CC: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/ohci-q.c | 46 +++++++++++++++++++++++++++++-----------------
1 file changed, 29 insertions(+), 17 deletions(-)
diff --git a/drivers/usb/host/ohci-q.c b/drivers/usb/host/ohci-q.c
index 517d04d5c150..a6376f3e55cb 100644
--- a/drivers/usb/host/ohci-q.c
+++ b/drivers/usb/host/ohci-q.c
@@ -311,8 +311,7 @@ static void periodic_unlink (struct ohci_hcd *ohci, struct ed *ed)
* - ED_OPER: when there's any request queued, the ED gets rescheduled
* immediately. HC should be working on them.
*
- * - ED_IDLE: when there's no TD queue. there's no reason for the HC
- * to care about this ED; safe to disable the endpoint.
+ * - ED_IDLE: when there's no TD queue or the HC isn't running.
*
* When finish_unlinks() runs later, after SOF interrupt, it will often
* complete one or more URB unlinks before making that state change.
@@ -954,6 +953,10 @@ rescan_all:
int completed, modified;
__hc32 *prev;
+ /* Is this ED already invisible to the hardware? */
+ if (ed->state == ED_IDLE)
+ goto ed_idle;
+
/* only take off EDs that the HC isn't using, accounting for
* frame counter wraps and EDs with partially retired TDs
*/
@@ -983,12 +986,20 @@ skip_ed:
}
}
+ /* ED's now officially unlinked, hc doesn't see */
+ ed->state = ED_IDLE;
+ if (quirk_zfmicro(ohci) && ed->type == PIPE_INTERRUPT)
+ ohci->eds_scheduled--;
+ ed->hwHeadP &= ~cpu_to_hc32(ohci, ED_H);
+ ed->hwNextED = 0;
+ wmb();
+ ed->hwINFO &= ~cpu_to_hc32(ohci, ED_SKIP | ED_DEQUEUE);
+ed_idle:
+
/* reentrancy: if we drop the schedule lock, someone might
* have modified this list. normally it's just prepending
* entries (which we'd ignore), but paranoia won't hurt.
*/
- *last = ed->ed_next;
- ed->ed_next = NULL;
modified = 0;
/* unlink urbs as requested, but rescan the list after
@@ -1046,19 +1057,20 @@ rescan_this:
if (completed && !list_empty (&ed->td_list))
goto rescan_this;
- /* ED's now officially unlinked, hc doesn't see */
- ed->state = ED_IDLE;
- if (quirk_zfmicro(ohci) && ed->type == PIPE_INTERRUPT)
- ohci->eds_scheduled--;
- ed->hwHeadP &= ~cpu_to_hc32(ohci, ED_H);
- ed->hwNextED = 0;
- wmb ();
- ed->hwINFO &= ~cpu_to_hc32 (ohci, ED_SKIP | ED_DEQUEUE);
-
- /* but if there's work queued, reschedule */
- if (!list_empty (&ed->td_list)) {
- if (ohci->rh_state == OHCI_RH_RUNNING)
- ed_schedule (ohci, ed);
+ /*
+ * If no TDs are queued, take ED off the ed_rm_list.
+ * Otherwise, if the HC is running, reschedule.
+ * If not, leave it on the list for further dequeues.
+ */
+ if (list_empty(&ed->td_list)) {
+ *last = ed->ed_next;
+ ed->ed_next = NULL;
+ } else if (ohci->rh_state == OHCI_RH_RUNNING) {
+ *last = ed->ed_next;
+ ed->ed_next = NULL;
+ ed_schedule(ohci, ed);
+ } else {
+ last = &ed->ed_next;
}
if (modified)
--
2.0.0.254.g50f84e3
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html