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Subject[01/98] USB: EHCI: defer reclamation of siTDs
2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Alan Stern <stern@rowland.harvard.edu>

commit 0e5f231bc16ff9910882fa5b9d64d80e7691cfab upstream.

This patch (as1369) fixes a problem in ehci-hcd. Some controllers
occasionally run into trouble when the driver reclaims siTDs too
quickly. This can happen while streaming audio; it causes the
controller to crash.

The patch changes siTD reclamation to work the same way as iTD
reclamation: Completed siTDs are stored on a list and not reused until
at least one frame has passed.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Nate Case <ncase@xes-inc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/usb/host/ehci-hcd.c | 1 +
drivers/usb/host/ehci-mem.c | 2 +-
drivers/usb/host/ehci-sched.c | 38 ++++++++++++++++++++++++++++++--------
drivers/usb/host/ehci.h | 5 +++--
4 files changed, 35 insertions(+), 11 deletions(-)
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -543,6 +543,7 @@ static int ehci_init(struct usb_hcd *hcd
*/
ehci->periodic_size = DEFAULT_I_TDPS;
INIT_LIST_HEAD(&ehci->cached_itd_list);
+ INIT_LIST_HEAD(&ehci->cached_sitd_list);
if ((retval = ehci_mem_init(ehci, GFP_KERNEL)) < 0)
return retval;

--- a/drivers/usb/host/ehci-mem.c
+++ b/drivers/usb/host/ehci-mem.c
@@ -136,7 +136,7 @@ static inline void qh_put (struct ehci_q

static void ehci_mem_cleanup (struct ehci_hcd *ehci)
{
- free_cached_itd_list(ehci);
+ free_cached_lists(ehci);
if (ehci->async)
qh_put (ehci->async);
ehci->async = NULL;
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -2127,13 +2127,27 @@ sitd_complete (
(stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out");
}
iso_stream_put (ehci, stream);
- /* OK to recycle this SITD now that its completion callback ran. */
+
done:
sitd->urb = NULL;
- sitd->stream = NULL;
- list_move(&sitd->sitd_list, &stream->free_list);
- iso_stream_put(ehci, stream);
-
+ if (ehci->clock_frame != sitd->frame) {
+ /* OK to recycle this SITD now. */
+ sitd->stream = NULL;
+ list_move(&sitd->sitd_list, &stream->free_list);
+ iso_stream_put(ehci, stream);
+ } else {
+ /* HW might remember this SITD, so we can't recycle it yet.
+ * Move it to a safe place until a new frame starts.
+ */
+ list_move(&sitd->sitd_list, &ehci->cached_sitd_list);
+ if (stream->refcount == 2) {
+ /* If iso_stream_put() were called here, stream
+ * would be freed. Instead, just prevent reuse.
+ */
+ stream->ep->hcpriv = NULL;
+ stream->ep = NULL;
+ }
+ }
return retval;
}

@@ -2199,9 +2213,10 @@ done:

/*-------------------------------------------------------------------------*/

-static void free_cached_itd_list(struct ehci_hcd *ehci)
+static void free_cached_lists(struct ehci_hcd *ehci)
{
struct ehci_itd *itd, *n;
+ struct ehci_sitd *sitd, *sn;

list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) {
struct ehci_iso_stream *stream = itd->stream;
@@ -2209,6 +2224,13 @@ static void free_cached_itd_list(struct
list_move(&itd->itd_list, &stream->free_list);
iso_stream_put(ehci, stream);
}
+
+ list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) {
+ struct ehci_iso_stream *stream = sitd->stream;
+ sitd->stream = NULL;
+ list_move(&sitd->sitd_list, &stream->free_list);
+ iso_stream_put(ehci, stream);
+ }
}

/*-------------------------------------------------------------------------*/
@@ -2235,7 +2257,7 @@ scan_periodic (struct ehci_hcd *ehci)
clock_frame = -1;
}
if (ehci->clock_frame != clock_frame) {
- free_cached_itd_list(ehci);
+ free_cached_lists(ehci);
ehci->clock_frame = clock_frame;
}
clock %= mod;
@@ -2398,7 +2420,7 @@ restart:
clock = now;
clock_frame = clock >> 3;
if (ehci->clock_frame != clock_frame) {
- free_cached_itd_list(ehci);
+ free_cached_lists(ehci);
ehci->clock_frame = clock_frame;
}
} else {
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -87,8 +87,9 @@ struct ehci_hcd { /* one per controlle
int next_uframe; /* scan periodic, start here */
unsigned periodic_sched; /* periodic activity count */

- /* list of itds completed while clock_frame was still active */
+ /* list of itds & sitds completed while clock_frame was still active */
struct list_head cached_itd_list;
+ struct list_head cached_sitd_list;
unsigned clock_frame;

/* per root hub port */
@@ -195,7 +196,7 @@ timer_action_done (struct ehci_hcd *ehci
clear_bit (action, &ehci->actions);
}

-static void free_cached_itd_list(struct ehci_hcd *ehci);
+static void free_cached_lists(struct ehci_hcd *ehci);

/*-------------------------------------------------------------------------*/




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