This patch (as1570) adds a pointer for the end of ehci-hcd's
async-unlink list. The list (which is actually a queue) is singly
linked, so having a pointer to its end makes adding new entries easier
-- there's no longer any need to scan through the whole list.
In principle it could be changed to a standard doubly-linked list. It
turns out that doing so actually makes the code less clear, so I'm
leaving it as is.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/ehci-hcd.c | 9 ++-------
drivers/usb/host/ehci-q.c | 2 ++
drivers/usb/host/ehci.h | 1 +
3 files changed, 5 insertions(+), 7 deletions(-)
Index: usb-3.4/drivers/usb/host/ehci.h
===================================================================
--- usb-3.4.orig/drivers/usb/host/ehci.h
+++ usb-3.4/drivers/usb/host/ehci.h
@@ -82,6 +82,7 @@ struct ehci_hcd { /* one per controlle
struct ehci_qh *async;
struct ehci_qh *dummy; /* For AMD quirk use */
struct ehci_qh *async_unlink;
+ struct ehci_qh *async_unlink_last;
struct ehci_qh *qh_scan_next;
unsigned scanning : 1;
Index: usb-3.4/drivers/usb/host/ehci-hcd.c
===================================================================
--- usb-3.4.orig/drivers/usb/host/ehci-hcd.c
+++ usb-3.4/drivers/usb/host/ehci-hcd.c
@@ -1041,14 +1041,9 @@ static void unlink_async (struct ehci_hc
/* defer till later if busy */
if (ehci->async_unlink) {
- struct ehci_qh *last;
-
- for (last = ehci->async_unlink;
- last->unlink_next;
- last = last->unlink_next)
- continue;
qh->qh_state = QH_STATE_UNLINK_WAIT;
- last->unlink_next = qh;
+ ehci->async_unlink_last->unlink_next = qh;
+ ehci->async_unlink_last = qh;
/* start IAA cycle */
} else
Index: usb-3.4/drivers/usb/host/ehci-q.c
===================================================================
--- usb-3.4.orig/drivers/usb/host/ehci-q.c
+++ usb-3.4/drivers/usb/host/ehci-q.c
@@ -1227,6 +1227,8 @@ static void start_unlink_async (struct e
qh->qh_state = QH_STATE_UNLINK;
ehci->async_unlink = qh;
+ if (!qh->unlink_next)
+ ehci->async_unlink_last = qh;
prev = ehci->async;
while (prev->qh_next.qh != qh)
--
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