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>

5 files changed, 8 insertions, 44 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index ab7306de8d16..1f8f792eec86 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -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 */
diff --git a/drivers/usb/host/ehci-mem.c b/drivers/usb/host/ehci-mem.c
index 12f70c302b0b..93132d8ad360 100644
--- a/drivers/usb/host/ehci-mem.c
+++ b/drivers/usb/host/ehci-mem.c
@@ -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 */
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 4378bf72bbac..7d117bbffac1 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -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;
                 }
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 33182c6d1ff9..027df3de2dc9 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -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
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 85c3572155d1..f7a59f5d70c6 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -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 */