USB: EHCI: don't refcount iso_stream structures

This patch (as1580) makes ehci_iso_stream structures behave more like
QHs, in that they will remain allocated until their isochronous
endpoint is disabled.  This will come in useful in the future, when
periodic bandwidth gets allocated as an altsetting is installed rather
than on-the-fly.

For now, the change to the ehci_iso_stream lifetimes means that each
structure is always deallocated at exactly one spot in
ehci_endpoint_disable() and never used again.  As a result, it is no
longer necessary to use reference counting on these things, and the
patch removes it.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 47 deletions

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 1e4f13c11b6..11b2f21d7ac 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -934,7 +934,6 @@ iso_stream_alloc (gfp_t mem_flags)
 		INIT_LIST_HEAD(&stream->td_list);
 		INIT_LIST_HEAD(&stream->free_list);
 		stream->next_uframe = -1;
-		stream->refcount = 1;
 	}
 	return stream;
 }
@@ -1034,32 +1033,6 @@ iso_stream_init (
 	stream->maxp = maxp;
 }
 
-static void
-iso_stream_put(struct ehci_hcd *ehci, struct ehci_iso_stream *stream)
-{
-	stream->refcount--;
-
-	/* free whenever just a dev->ep reference remains.
-	 * not like a QH -- no persistent state (toggle, halt)
-	 */
-	if (stream->refcount == 1) {
-		// BUG_ON (!list_empty(&stream->td_list));
-
-		if (stream->ep)
-			stream->ep->hcpriv = NULL;
-
-		kfree(stream);
-	}
-}
-
-static inline struct ehci_iso_stream *
-iso_stream_get (struct ehci_iso_stream *stream)
-{
-	if (likely (stream != NULL))
-		stream->refcount++;
-	return stream;
-}
-
 static struct ehci_iso_stream *
 iso_stream_find (struct ehci_hcd *ehci, struct urb *urb)
 {
@@ -1080,7 +1053,6 @@ iso_stream_find (struct ehci_hcd *ehci, struct urb *urb)
 	if (unlikely (stream == NULL)) {
 		stream = iso_stream_alloc(GFP_ATOMIC);
 		if (likely (stream != NULL)) {
-			/* dev->ep owns the initial refcount */
 			ep->hcpriv = stream;
 			stream->ep = ep;
 			iso_stream_init(ehci, stream, urb->dev, urb->pipe,
@@ -1095,9 +1067,6 @@ iso_stream_find (struct ehci_hcd *ehci, struct urb *urb)
 		stream = NULL;
 	}
 
-	/* caller guarantees an eventual matching iso_stream_put */
-	stream = iso_stream_get (stream);
-
 	spin_unlock_irqrestore (&ehci->lock, flags);
 	return stream;
 }
@@ -1611,7 +1580,7 @@ static void itd_link_urb(
 			itd = list_entry (iso_sched->td_list.next,
 					struct ehci_itd, itd_list);
 			list_move_tail (&itd->itd_list, &stream->td_list);
-			itd->stream = iso_stream_get (stream);
+			itd->stream = stream;
 			itd->urb = urb;
 			itd_init (ehci, stream, itd);
 		}
@@ -1735,7 +1704,6 @@ itd_complete (
 			dev->devpath, stream->bEndpointAddress & 0x0f,
 			(stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out");
 	}
-	iso_stream_put (ehci, stream);
 
 done:
 	itd->urb = NULL;
@@ -1750,7 +1718,6 @@ done:
 		start_free_itds(ehci);
 	}
 
-	iso_stream_put(ehci, stream);
 	return retval;
 }
 
@@ -1807,12 +1774,9 @@ static int itd_submit (struct ehci_hcd *ehci, struct urb *urb,
 		itd_link_urb (ehci, urb, ehci->periodic_size << 3, stream);
 	else
 		usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
-done_not_linked:
+ done_not_linked:
 	spin_unlock_irqrestore (&ehci->lock, flags);
-
-done:
-	if (unlikely (status < 0))
-		iso_stream_put (ehci, stream);
+ done:
 	return status;
 }
 
@@ -2028,7 +1992,7 @@ static void sitd_link_urb(
 		sitd = list_entry (sched->td_list.next,
 				struct ehci_sitd, sitd_list);
 		list_move_tail (&sitd->sitd_list, &stream->td_list);
-		sitd->stream = iso_stream_get (stream);
+		sitd->stream = stream;
 		sitd->urb = urb;
 
 		sitd_patch(ehci, stream, sitd, sched, packet);
@@ -2126,7 +2090,6 @@ sitd_complete (
 			dev->devpath, stream->bEndpointAddress & 0x0f,
 			(stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out");
 	}
-	iso_stream_put (ehci, stream);
 
 done:
 	sitd->urb = NULL;
@@ -2141,7 +2104,6 @@ done:
 		start_free_itds(ehci);
 	}
 
-	iso_stream_put(ehci, stream);
 	return retval;
 }
 
@@ -2195,12 +2157,9 @@ static int sitd_submit (struct ehci_hcd *ehci, struct urb *urb,
 		sitd_link_urb (ehci, urb, ehci->periodic_size << 3, stream);
 	else
 		usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
-done_not_linked:
+ done_not_linked:
 	spin_unlock_irqrestore (&ehci->lock, flags);
-
-done:
-	if (status < 0)
-		iso_stream_put (ehci, stream);
+ done:
 	return status;
 }