USB: reorganize urb->status use in ehci-hcd

This patch (as974) reorganizes the way ehci-hcd sets urb->status.  It
now keeps the information in a local variable until the last moment.

The patch also simplifies the handling of -EREMOTEIO, since the only
use of that code is to set the do_status flag.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 35 insertions, 31 deletions

diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index a8f5408c161d..794d27e07807 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -139,63 +139,65 @@ qh_refresh (struct ehci_hcd *ehci, struct ehci_qh *qh)
 
 /*-------------------------------------------------------------------------*/
 
-static void qtd_copy_status (
+static int qtd_copy_status (
         struct ehci_hcd *ehci,
         struct urb *urb,
         size_t length,
         u32 token
 )
 {
+        int     status = -EINPROGRESS;
+
         /* count IN/OUT bytes, not SETUP (even short packets) */
         if (likely (QTD_PID (token) != 2))
                 urb->actual_length += length - QTD_LENGTH (token);
 
         /* don't modify error codes */
         if (unlikely(urb->unlinked))
-                return;
+                return status;
 
         /* force cleanup after short read; not always an error */
         if (unlikely (IS_SHORT_READ (token)))
-                urb->status = -EREMOTEIO;
+                status = -EREMOTEIO;
 
         /* serious "can't proceed" faults reported by the hardware */
         if (token & QTD_STS_HALT) {
                 if (token & QTD_STS_BABBLE) {
                         /* FIXME "must" disable babbling device's port too */
-                        urb->status = -EOVERFLOW;
+                        status = -EOVERFLOW;
                 } else if (token & QTD_STS_MMF) {
                         /* fs/ls interrupt xfer missed the complete-split */
-                        urb->status = -EPROTO;
+                        status = -EPROTO;
                 } else if (token & QTD_STS_DBE) {
-                        urb->status = (QTD_PID (token) == 1) /* IN ? */
+                        status = (QTD_PID (token) == 1) /* IN ? */
                                 ? -ENOSR  /* hc couldn't read data */
                                 : -ECOMM; /* hc couldn't write data */
                 } else if (token & QTD_STS_XACT) {
                         /* timeout, bad crc, wrong PID, etc; retried */
                         if (QTD_CERR (token))
-                                urb->status = -EPIPE;
+                                status = -EPIPE;
                         else {
                                 ehci_dbg (ehci, "devpath %s ep%d%s 3strikes\n",
                                         urb->dev->devpath,
                                         usb_pipeendpoint (urb->pipe),
                                         usb_pipein (urb->pipe) ? "in" : "out");
-                                urb->status = -EPROTO;
+                                status = -EPROTO;
                         }
                 /* CERR nonzero + no errors + halt --> stall */
                 } else if (QTD_CERR (token))
-                        urb->status = -EPIPE;
+                        status = -EPIPE;
                 else    /* unknown */
-                        urb->status = -EPROTO;
+                        status = -EPROTO;
 
                 ehci_vdbg (ehci,
                         "dev%d ep%d%s qtd token %08x --> status %d\n",
                         usb_pipedevice (urb->pipe),
                         usb_pipeendpoint (urb->pipe),
                         usb_pipein (urb->pipe) ? "in" : "out",
-                        token, urb->status);
+                        token, status);
 
                 /* if async CSPLIT failed, try cleaning out the TT buffer */
-                if (urb->status != -EPIPE
+                if (status != -EPIPE
                                 && urb->dev->tt && !usb_pipeint (urb->pipe)
                                 && ((token & QTD_STS_MMF) != 0
                                         || QTD_CERR(token) == 0)
@@ -212,10 +214,12 @@ static void qtd_copy_status (
                         usb_hub_tt_clear_buffer (urb->dev, urb->pipe);
                 }
         }
+
+        return status;
 }
 
 static void
-ehci_urb_done (struct ehci_hcd *ehci, struct urb *urb)
+ehci_urb_done(struct ehci_hcd *ehci, struct urb *urb, int status)
 __releases(ehci->lock)
 __acquires(ehci->lock)
 {
@@ -231,17 +235,13 @@ __acquires(ehci->lock)
                 qh_put (qh);
         }
 
-        spin_lock (&urb->lock);
         if (unlikely(urb->unlinked)) {
                 COUNT(ehci->stats.unlink);
         } else {
-                if (likely(urb->status == -EINPROGRESS ||
-                                (urb->status == -EREMOTEIO &&
-                                 !(urb->transfer_flags & URB_SHORT_NOT_OK))))
-                        urb->status = 0;
+                if (likely(status == -EINPROGRESS))
+                        status = 0;
                 COUNT(ehci->stats.complete);
         }
-        spin_unlock (&urb->lock);
 
 #ifdef EHCI_URB_TRACE
         ehci_dbg (ehci,
@@ -249,13 +249,14 @@ __acquires(ehci->lock)
                 __FUNCTION__, urb->dev->devpath, urb,
                 usb_pipeendpoint (urb->pipe),
                 usb_pipein (urb->pipe) ? "in" : "out",
-                urb->status,
+                status,
                 urb->actual_length, urb->transfer_buffer_length);
 #endif
 
         /* complete() can reenter this HCD */
         usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
         spin_unlock (&ehci->lock);
+        urb->status = status;
         usb_hcd_giveback_urb (ehci_to_hcd(ehci), urb);
         spin_lock (&ehci->lock);
 }
@@ -276,6 +277,7 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 {
         struct ehci_qtd         *last = NULL, *end = qh->dummy;
         struct list_head        *entry, *tmp;
+        int                     last_status = -EINPROGRESS;
         int                     stopped;
         unsigned                count = 0;
         int                     do_status = 0;
@@ -304,6 +306,7 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
                 struct ehci_qtd *qtd;
                 struct urb      *urb;
                 u32             token = 0;
+                int             qtd_status;
 
                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
                 urb = qtd->urb;
@@ -311,11 +314,12 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
                 /* clean up any state from previous QTD ...*/
                 if (last) {
                         if (likely (last->urb != urb)) {
-                                ehci_urb_done (ehci, last->urb);
+                                ehci_urb_done(ehci, last->urb, last_status);
                                 count++;
                         }
                         ehci_qtd_free (ehci, last);
                         last = NULL;
+                        last_status = -EINPROGRESS;
                 }
 
                 /* ignore urbs submitted during completions we reported */
@@ -351,13 +355,13 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
                         stopped = 1;
 
                         if (unlikely (!HC_IS_RUNNING (ehci_to_hcd(ehci)->state)))
-                                urb->status = -ESHUTDOWN;
+                                last_status = -ESHUTDOWN;
 
                         /* ignore active urbs unless some previous qtd
                          * for the urb faulted (including short read) or
                          * its urb was canceled.  we may patch qh or qtds.
                          */
-                        if (likely(urb->status == -EINPROGRESS &&
+                        if (likely(last_status == -EINPROGRESS &&
                                         !urb->unlinked))
                                 continue;
 
@@ -386,14 +390,14 @@ halt:
                 }
 
                 /* remove it from the queue */
-                spin_lock (&urb->lock);
-                qtd_copy_status (ehci, urb, qtd->length, token);
-                if (unlikely(urb->status == -EREMOTEIO)) {
+                qtd_status = qtd_copy_status(ehci, urb, qtd->length, token);
+                if (unlikely(qtd_status == -EREMOTEIO)) {
                         do_status = (!urb->unlinked &&
                                         usb_pipecontrol(urb->pipe));
-                        urb->status = 0;
+                        qtd_status = 0;
                 }
-                spin_unlock (&urb->lock);
+                if (likely(last_status == -EINPROGRESS))
+                        last_status = qtd_status;
 
                 if (stopped && qtd->qtd_list.prev != &qh->qtd_list) {
                         last = list_entry (qtd->qtd_list.prev,
@@ -406,7 +410,7 @@ halt:
 
         /* last urb's completion might still need calling */
         if (likely (last != NULL)) {
-                ehci_urb_done (ehci, last->urb);
+                ehci_urb_done(ehci, last->urb, last_status);
                 count++;
                 ehci_qtd_free (ehci, last);
         }
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 8b267b3fd2bb..80d99bce2b38 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1627,7 +1627,7 @@ itd_complete (
 
         /* give urb back to the driver ... can be out-of-order */
         dev = urb->dev;
-        ehci_urb_done (ehci, urb);
+        ehci_urb_done(ehci, urb, 0);
         urb = NULL;
 
         /* defer stopping schedule; completion can submit */
@@ -2000,7 +2000,7 @@ sitd_complete (
 
         /* give urb back to the driver */
         dev = urb->dev;
-        ehci_urb_done (ehci, urb);
+        ehci_urb_done(ehci, urb, 0);
         urb = NULL;
 
         /* defer stopping schedule; completion can submit */