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Commit c83e1a9f authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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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: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 15be105b

drivers/usb/host/ehci-hcd.c

+1 −1
Original line number Diff line number Diff line
@@ -1179,7 +1179,7 @@ ehci_endpoint_disable (struct usb_hcd *hcd, struct usb_host_endpoint *ep) 
		if (qh->clearing_tt)

			goto idle_timeout;

		if (list_empty (&qh->qtd_list)) {

			qh_put (qh);

			qh_destroy(ehci, qh);

			break;

		}

		/* else FALL THROUGH */

drivers/usb/host/ehci-mem.c

+3 −21
Original line number Diff line number Diff line
@@ -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 @@ static struct ehci_qh *ehci_qh_alloc (struct ehci_hcd *ehci, gfp_t flags) 
	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 */

drivers/usb/host/ehci-q.c

+3 −9
Original line number Diff line number Diff line
@@ -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;

		}

drivers/usb/host/ehci-sched.c

+1 −4
Original line number Diff line number Diff line
@@ -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 @@ scan_periodic (struct ehci_hcd *ehci) 
			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 @@ scan_periodic (struct ehci_hcd *ehci) 
							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

drivers/usb/host/ehci.h

+0 −9
Original line number Diff line number Diff line
@@ -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 */