USB: EHCI: convert singly-linked lists to list_heads
This patch (as1664) converts ehci-hcd's async_unlink, async_iaa, and
intr_unlink from singly-linked lists to standard doubly-linked
list_heads. Originally it didn't seem necessary to use list_heads,
because items are always added to and removed from these lists in FIFO
order. But now with more list processing going on, it's easier to use
the standard routines than continue with a roll-your-own approach.
I don't know if the code ends up being notably shorter, but the
patterns will be more familiar to any kernel hacker.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/host/ehci-dbg.c b/drivers/usb/host/ehci-dbg.c
index 70b496d..5429d26 100644
--- a/drivers/usb/host/ehci-dbg.c
+++ b/drivers/usb/host/ehci-dbg.c
@@ -510,14 +510,16 @@
spin_lock_irqsave (&ehci->lock, flags);
for (qh = ehci->async->qh_next.qh; size > 0 && qh; qh = qh->qh_next.qh)
qh_lines (ehci, qh, &next, &size);
- if (ehci->async_unlink && size > 0) {
+ if (!list_empty(&ehci->async_unlink) && size > 0) {
temp = scnprintf(next, size, "\nunlink =\n");
size -= temp;
next += temp;
- for (qh = ehci->async_unlink; size > 0 && qh;
- qh = qh->unlink_next)
- qh_lines (ehci, qh, &next, &size);
+ list_for_each_entry(qh, &ehci->async_unlink, unlink_node) {
+ if (size <= 0)
+ break;
+ qh_lines(ehci, qh, &next, &size);
+ }
}
spin_unlock_irqrestore (&ehci->lock, flags);
@@ -814,9 +816,10 @@
}
}
- if (ehci->async_unlink) {
+ if (!list_empty(&ehci->async_unlink)) {
temp = scnprintf(next, size, "async unlink qh %p\n",
- ehci->async_unlink);
+ list_first_entry(&ehci->async_unlink,
+ struct ehci_qh, unlink_node));
size -= temp;
next += temp;
}
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 87fe3da..b32323c 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -482,6 +482,9 @@
* periodic_size can shrink by USBCMD update if hcc_params allows.
*/
ehci->periodic_size = DEFAULT_I_TDPS;
+ INIT_LIST_HEAD(&ehci->async_unlink);
+ INIT_LIST_HEAD(&ehci->async_iaa);
+ INIT_LIST_HEAD(&ehci->intr_unlink);
INIT_LIST_HEAD(&ehci->intr_qh_list);
INIT_LIST_HEAD(&ehci->cached_itd_list);
INIT_LIST_HEAD(&ehci->cached_sitd_list);
@@ -749,7 +752,7 @@
/* guard against (alleged) silicon errata */
if (cmd & CMD_IAAD)
ehci_dbg(ehci, "IAA with IAAD still set?\n");
- if (ehci->async_iaa)
+ if (!list_empty(&ehci->async_iaa))
COUNT(ehci->stats.iaa);
end_unlink_async(ehci);
}
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index fca741d..4a01367 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -958,8 +958,9 @@
if (--ehci->async_count)
return;
- /* The async schedule and async_unlink list are supposed to be empty */
- WARN_ON(ehci->async->qh_next.qh || ehci->async_unlink);
+ /* The async schedule and unlink lists are supposed to be empty */
+ WARN_ON(ehci->async->qh_next.qh || !list_empty(&ehci->async_unlink) ||
+ !list_empty(&ehci->async_iaa));
/* Don't turn off the schedule until ASS is 1 */
ehci_poll_ASS(ehci);
@@ -1150,11 +1151,7 @@
/* Add to the end of the list of QHs waiting for the next IAAD */
qh->qh_state = QH_STATE_UNLINK_WAIT;
- if (ehci->async_unlink)
- ehci->async_unlink_last->unlink_next = qh;
- else
- ehci->async_unlink = qh;
- ehci->async_unlink_last = qh;
+ list_add_tail(&qh->unlink_node, &ehci->async_unlink);
/* Unlink it from the schedule */
prev = ehci->async;
@@ -1173,15 +1170,14 @@
* Do nothing if an IAA cycle is already running or
* if one will be started shortly.
*/
- if (ehci->async_iaa || ehci->async_unlinking)
+ if (!list_empty(&ehci->async_iaa) || ehci->async_unlinking)
return;
/* If the controller isn't running, we don't have to wait for it */
if (unlikely(ehci->rh_state < EHCI_RH_RUNNING)) {
/* Do all the waiting QHs */
- ehci->async_iaa = ehci->async_unlink;
- ehci->async_unlink = NULL;
+ list_splice_tail_init(&ehci->async_unlink, &ehci->async_iaa);
if (!nested) /* Avoid recursion */
end_unlink_async(ehci);
@@ -1191,20 +1187,18 @@
struct ehci_qh *qh;
/* Do only the first waiting QH (nVidia bug?) */
- qh = ehci->async_unlink;
+ qh = list_first_entry(&ehci->async_unlink, struct ehci_qh,
+ unlink_node);
/*
* Intel (?) bug: The HC can write back the overlay region
* even after the IAA interrupt occurs. In self-defense,
* always go through two IAA cycles for each QH.
*/
- if (qh->qh_state == QH_STATE_UNLINK_WAIT) {
+ if (qh->qh_state == QH_STATE_UNLINK_WAIT)
qh->qh_state = QH_STATE_UNLINK;
- } else {
- ehci->async_iaa = qh;
- ehci->async_unlink = qh->unlink_next;
- qh->unlink_next = NULL;
- }
+ else
+ list_move_tail(&qh->unlink_node, &ehci->async_iaa);
/* Make sure the unlinks are all visible to the hardware */
wmb();
@@ -1229,10 +1223,10 @@
/* Process the idle QHs */
restart:
ehci->async_unlinking = true;
- while (ehci->async_iaa) {
- qh = ehci->async_iaa;
- ehci->async_iaa = qh->unlink_next;
- qh->unlink_next = NULL;
+ while (!list_empty(&ehci->async_iaa)) {
+ qh = list_first_entry(&ehci->async_iaa, struct ehci_qh,
+ unlink_node);
+ list_del(&qh->unlink_node);
qh->qh_state = QH_STATE_IDLE;
qh->qh_next.qh = NULL;
@@ -1247,7 +1241,7 @@
ehci->async_unlinking = false;
/* Start a new IAA cycle if any QHs are waiting for it */
- if (ehci->async_unlink) {
+ if (!list_empty(&ehci->async_unlink)) {
start_iaa_cycle(ehci, true);
if (unlikely(ehci->rh_state < EHCI_RH_RUNNING))
goto restart;
@@ -1276,7 +1270,8 @@
}
/* If nothing else is being unlinked, unlink the last empty QH */
- if (!ehci->async_iaa && !ehci->async_unlink && qh_to_unlink) {
+ if (list_empty(&ehci->async_iaa) && list_empty(&ehci->async_unlink) &&
+ qh_to_unlink) {
start_unlink_async(ehci, qh_to_unlink);
--count;
}
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index e7a2dbd..c833feb 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -620,17 +620,13 @@
qh->unlink_cycle = ehci->intr_unlink_cycle;
/* New entries go at the end of the intr_unlink list */
- if (ehci->intr_unlink)
- ehci->intr_unlink_last->unlink_next = qh;
- else
- ehci->intr_unlink = qh;
- ehci->intr_unlink_last = qh;
+ list_add_tail(&qh->unlink_node, &ehci->intr_unlink);
if (ehci->intr_unlinking)
; /* Avoid recursive calls */
else if (ehci->rh_state < EHCI_RH_RUNNING)
ehci_handle_intr_unlinks(ehci);
- else if (ehci->intr_unlink == qh) {
+ else if (ehci->intr_unlink.next == &qh->unlink_node) {
ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true);
++ehci->intr_unlink_cycle;
}
diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
index e736333..f63a983 100644
--- a/drivers/usb/host/ehci-timer.c
+++ b/drivers/usb/host/ehci-timer.c
@@ -229,18 +229,19 @@
* process all the QHs on the list.
*/
ehci->intr_unlinking = true;
- while (ehci->intr_unlink) {
- struct ehci_qh *qh = ehci->intr_unlink;
+ while (!list_empty(&ehci->intr_unlink)) {
+ struct ehci_qh *qh;
+ qh = list_first_entry(&ehci->intr_unlink, struct ehci_qh,
+ unlink_node);
if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle)
break;
- ehci->intr_unlink = qh->unlink_next;
- qh->unlink_next = NULL;
+ list_del(&qh->unlink_node);
end_unlink_intr(ehci, qh);
}
/* Handle remaining entries later */
- if (ehci->intr_unlink) {
+ if (!list_empty(&ehci->intr_unlink)) {
ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true);
++ehci->intr_unlink_cycle;
}
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 6815209..13f6704 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -128,9 +128,8 @@
/* async schedule support */
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 *async_iaa;
+ struct list_head async_unlink;
+ struct list_head async_iaa;
unsigned async_unlink_cycle;
unsigned async_count; /* async activity count */
@@ -143,8 +142,7 @@
unsigned i_thresh; /* uframes HC might cache */
union ehci_shadow *pshadow; /* mirror hw periodic table */
- struct ehci_qh *intr_unlink;
- struct ehci_qh *intr_unlink_last;
+ struct list_head intr_unlink;
unsigned intr_unlink_cycle;
unsigned now_frame; /* frame from HC hardware */
unsigned last_iso_frame; /* last frame scanned for iso */
@@ -380,7 +378,7 @@
struct list_head qtd_list; /* sw qtd list */
struct list_head intr_node; /* list of intr QHs */
struct ehci_qtd *dummy;
- struct ehci_qh *unlink_next; /* next on unlink list */
+ struct list_head unlink_node;
unsigned unlink_cycle;