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USB: EHCI: don't refcount QHs 

This patch (as1567) removes ehci-hcd's reference counting of QH
structures.  It's not necessary to refcount these things because they
always get deallocated at exactly one spot in ehci_endpoint_disable()
(except for two special QHs, ehci->async and ehci->dummy) and are
never used again.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alan Stern 2012-07-11 11:21:25 -04:00 committed by Greg Kroah-Hartman
parent 15be105b4a
commit c83e1a9ff6
5 changed files with 8 additions and 44 deletions
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2
drivers/usb/host/ehci-hcd.c
View File

@ -1179,7 +1179,7 @@ idle_timeout:
if (qh->clearing_tt)
goto idle_timeout;
if (list_empty (&qh->qtd_list)) {
qh_put (qh);
qh_destroy(ehci, qh);
break;
}
/* else FALL THROUGH */

24
drivers/usb/host/ehci-mem.c
View File

@ -64,10 +64,8 @@ static inline void ehci_qtd_free (struct ehci_hcd *ehci, struct ehci_qtd *qtd)
}
static void qh_destroy(struct ehci_qh *qh)
static void qh_destroy(struct ehci_hcd *ehci, struct ehci_qh *qh)
{
struct ehci_hcd *ehci = qh->ehci;
/* clean qtds first, and know this is not linked */
if (!list_empty (&qh->qtd_list) || qh->qh_next.ptr) {
ehci_dbg (ehci, "unused qh not empty!\n");
@ -92,8 +90,6 @@ static struct ehci_qh *ehci_qh_alloc (struct ehci_hcd *ehci, gfp_t flags)
if (!qh->hw)
goto fail;
memset(qh->hw, 0, sizeof *qh->hw);
qh->refcount = 1;
qh->ehci = ehci;
qh->qh_dma = dma;
// INIT_LIST_HEAD (&qh->qh_list);
INIT_LIST_HEAD (&qh->qtd_list);
@ -113,20 +109,6 @@ fail:
return NULL;
}
/* to share a qh (cpu threads, or hc) */
static inline struct ehci_qh *qh_get (struct ehci_qh *qh)
{
WARN_ON(!qh->refcount);
qh->refcount++;
return qh;
}
static inline void qh_put (struct ehci_qh *qh)
{
if (!--qh->refcount)
qh_destroy(qh);
}
/*-------------------------------------------------------------------------*/
/* The queue heads and transfer descriptors are managed from pools tied
@ -138,11 +120,11 @@ static void ehci_mem_cleanup (struct ehci_hcd *ehci)
{
free_cached_lists(ehci);
if (ehci->async)
qh_put (ehci->async);
qh_destroy(ehci, ehci->async);
ehci->async = NULL;
if (ehci->dummy)
qh_put(ehci->dummy);
qh_destroy(ehci, ehci->dummy);
ehci->dummy = NULL;
/* DMA consistent memory and pools */

12
drivers/usb/host/ehci-q.c
View File

@ -265,7 +265,6 @@ __acquires(ehci->lock)
/* ... update hc-wide periodic stats (for usbfs) */
ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
}
qh_put (qh);
}
if (unlikely(urb->unlinked)) {
@ -946,7 +945,7 @@ qh_make (
ehci_dbg(ehci, "bogus dev %p speed %d\n", urb->dev,
urb->dev->speed);
done:
qh_put (qh);
qh_destroy(ehci, qh);
return NULL;
}
@ -1003,7 +1002,6 @@ static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
head->qh_next.qh = qh;
head->hw->hw_next = dma;
qh_get(qh);
qh->xacterrs = 0;
qh->qh_state = QH_STATE_LINKED;
/* qtd completions reported later by interrupt */
@ -1090,7 +1088,7 @@ static struct ehci_qh *qh_append_tds (
wmb ();
dummy->hw_token = token;
urb->hcpriv = qh_get (qh);
urb->hcpriv = qh;
}
}
return qh;
@ -1167,7 +1165,6 @@ static void end_unlink_async (struct ehci_hcd *ehci)
// qh->hw_next = cpu_to_hc32(qh->qh_dma);
qh->qh_state = QH_STATE_IDLE;
qh->qh_next.qh = NULL;
qh_put (qh); // refcount from reclaim
/* other unlink(s) may be pending (in QH_STATE_UNLINK_WAIT) */
next = qh->reclaim;
@ -1186,7 +1183,6 @@ static void end_unlink_async (struct ehci_hcd *ehci)
&& ehci->async->qh_next.qh == NULL)
timer_action (ehci, TIMER_ASYNC_OFF);
}
qh_put(qh); /* refcount from async list */
if (next) {
ehci->reclaim = NULL;
@ -1230,7 +1226,7 @@ static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
}
qh->qh_state = QH_STATE_UNLINK;
ehci->reclaim = qh = qh_get (qh);
ehci->reclaim = qh;
prev = ehci->async;
while (prev->qh_next.qh != qh)
@ -1283,12 +1279,10 @@ static void scan_async (struct ehci_hcd *ehci)
* gets unlinked then ehci->qh_scan_next is adjusted
* in start_unlink_async().
*/
qh = qh_get(qh);
temp = qh_completions(ehci, qh);
if (qh->needs_rescan)
unlink_async(ehci, qh);
qh->unlink_time = jiffies + EHCI_SHRINK_JIFFIES;
qh_put(qh);
if (temp != 0)
goto rescan;
}

5
drivers/usb/host/ehci-sched.c
View File

@ -606,7 +606,6 @@ static int qh_link_periodic (struct ehci_hcd *ehci, struct ehci_qh *qh)
}
qh->qh_state = QH_STATE_LINKED;
qh->xacterrs = 0;
qh_get (qh);
/* update per-qh bandwidth for usbfs */
ehci_to_hcd(ehci)->self.bandwidth_allocated += qh->period
@ -650,7 +649,6 @@ static int qh_unlink_periodic(struct ehci_hcd *ehci, struct ehci_qh *qh)
/* qh->qh_next still "live" to HC */
qh->qh_state = QH_STATE_UNLINK;
qh->qh_next.ptr = NULL;
qh_put (qh);
/* maybe turn off periodic schedule */
return disable_periodic(ehci);
@ -2340,7 +2338,7 @@ restart:
switch (hc32_to_cpu(ehci, type)) {
case Q_TYPE_QH:
/* handle any completions */
temp.qh = qh_get (q.qh);
temp.qh = q.qh;
type = Q_NEXT_TYPE(ehci, q.qh->hw->hw_next);
q = q.qh->qh_next;
if (temp.qh->stamp != ehci->periodic_stamp) {
@ -2351,7 +2349,6 @@ restart:
temp.qh->needs_rescan))
intr_deschedule(ehci, temp.qh);
}
qh_put (temp.qh);
break;
case Q_TYPE_FSTN:
/* for "save place" FSTNs, look at QH entries

9
drivers/usb/host/ehci.h
View File

@ -350,16 +350,7 @@ struct ehci_qh {
struct ehci_qtd *dummy;
struct ehci_qh *reclaim; /* next to reclaim */
struct ehci_hcd *ehci;
unsigned long unlink_time;
/*
* Do NOT use atomic operations for QH refcounting. On some CPUs
* (PPC7448 for example), atomic operations cannot be performed on
* memory that is cache-inhibited (i.e. being used for DMA).
* Spinlocks are used to protect all QH fields.
*/
u32 refcount;
unsigned stamp;
u8 needs_rescan; /* Dequeue during giveback */