UHCI: Fix problem caused by lack of terminating QH
This patch (as871) fixes a problem introduced by an earlier change.
It turns out that some systems really do need to have a terminating
skeleton QH present whenever FSBR is on. I don't know any way to tell
which systems do need it and which don't; the easiest answer is to
have it there always.
This fixes the NumLock-hang bug reported by Jiri Slaby.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c
index f4ebdb3..19a0cc0 100644
--- a/drivers/usb/host/uhci-q.c
+++ b/drivers/usb/host/uhci-q.c
@@ -45,43 +45,27 @@
*/
static void uhci_fsbr_on(struct uhci_hcd *uhci)
{
- struct uhci_qh *fsbr_qh, *lqh, *tqh;
+ struct uhci_qh *lqh;
+ /* The terminating skeleton QH always points back to the first
+ * FSBR QH. Make the last async QH point to the terminating
+ * skeleton QH. */
uhci->fsbr_is_on = 1;
lqh = list_entry(uhci->skel_async_qh->node.prev,
struct uhci_qh, node);
-
- /* Find the first FSBR QH. Linear search through the list is
- * acceptable because normally FSBR gets turned on as soon as
- * one QH needs it. */
- fsbr_qh = NULL;
- list_for_each_entry_reverse(tqh, &uhci->skel_async_qh->node, node) {
- if (tqh->skel < SKEL_FSBR)
- break;
- fsbr_qh = tqh;
- }
-
- /* No FSBR QH means we must insert the terminating skeleton QH */
- if (!fsbr_qh) {
- uhci->skel_term_qh->link = LINK_TO_QH(uhci->skel_term_qh);
- wmb();
- lqh->link = uhci->skel_term_qh->link;
-
- /* Otherwise loop the last QH to the first FSBR QH */
- } else
- lqh->link = LINK_TO_QH(fsbr_qh);
+ lqh->link = LINK_TO_QH(uhci->skel_term_qh);
}
static void uhci_fsbr_off(struct uhci_hcd *uhci)
{
struct uhci_qh *lqh;
+ /* Remove the link from the last async QH to the terminating
+ * skeleton QH. */
uhci->fsbr_is_on = 0;
lqh = list_entry(uhci->skel_async_qh->node.prev,
struct uhci_qh, node);
-
- /* End the async list normally and unlink the terminating QH */
- lqh->link = uhci->skel_term_qh->link = UHCI_PTR_TERM;
+ lqh->link = UHCI_PTR_TERM;
}
static void uhci_add_fsbr(struct uhci_hcd *uhci, struct urb *urb)
@@ -464,9 +448,8 @@
*/
static void link_async(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
- struct uhci_qh *pqh, *lqh;
+ struct uhci_qh *pqh;
__le32 link_to_new_qh;
- __le32 *extra_link = &link_to_new_qh;
/* Find the predecessor QH for our new one and insert it in the list.
* The list of QHs is expected to be short, so linear search won't
@@ -476,31 +459,17 @@
break;
}
list_add(&qh->node, &pqh->node);
- qh->link = pqh->link;
-
- link_to_new_qh = LINK_TO_QH(qh);
-
- /* If this is now the first FSBR QH, take special action */
- if (uhci->fsbr_is_on && pqh->skel < SKEL_FSBR &&
- qh->skel >= SKEL_FSBR) {
- lqh = list_entry(uhci->skel_async_qh->node.prev,
- struct uhci_qh, node);
-
- /* If the new QH is also the last one, we must unlink
- * the terminating skeleton QH and make the new QH point
- * back to itself. */
- if (qh == lqh) {
- qh->link = link_to_new_qh;
- extra_link = &uhci->skel_term_qh->link;
-
- /* Otherwise the last QH must point to the new QH */
- } else
- extra_link = &lqh->link;
- }
/* Link it into the schedule */
+ qh->link = pqh->link;
wmb();
- *extra_link = pqh->link = link_to_new_qh;
+ link_to_new_qh = LINK_TO_QH(qh);
+ pqh->link = link_to_new_qh;
+
+ /* If this is now the first FSBR QH, link the terminating skeleton
+ * QH to it. */
+ if (pqh->skel < SKEL_FSBR && qh->skel >= SKEL_FSBR)
+ uhci->skel_term_qh->link = link_to_new_qh;
}
/*
@@ -561,31 +530,16 @@
*/
static void unlink_async(struct uhci_hcd *uhci, struct uhci_qh *qh)
{
- struct uhci_qh *pqh, *lqh;
+ struct uhci_qh *pqh;
__le32 link_to_next_qh = qh->link;
pqh = list_entry(qh->node.prev, struct uhci_qh, node);
-
- /* If this is the first FSBQ QH, take special action */
- if (uhci->fsbr_is_on && pqh->skel < SKEL_FSBR &&
- qh->skel >= SKEL_FSBR) {
- lqh = list_entry(uhci->skel_async_qh->node.prev,
- struct uhci_qh, node);
-
- /* If this QH is also the last one, we must link in
- * the terminating skeleton QH. */
- if (qh == lqh) {
- link_to_next_qh = LINK_TO_QH(uhci->skel_term_qh);
- uhci->skel_term_qh->link = link_to_next_qh;
- wmb();
- qh->link = link_to_next_qh;
-
- /* Otherwise the last QH must point to the new first FSBR QH */
- } else
- lqh->link = link_to_next_qh;
- }
-
pqh->link = link_to_next_qh;
+
+ /* If this was the old first FSBR QH, link the terminating skeleton
+ * QH to the next (new first FSBR) QH. */
+ if (pqh->skel < SKEL_FSBR && qh->skel >= SKEL_FSBR)
+ uhci->skel_term_qh->link = link_to_next_qh;
mb();
}
@@ -1217,7 +1171,7 @@
if (debug > 1 && errbuf) {
/* Print the chain for debugging */
- uhci_show_qh(urbp->qh, errbuf,
+ uhci_show_qh(uhci, urbp->qh, errbuf,
ERRBUF_LEN, 0);
lprintk(errbuf);
}