USB: EHCI: fix initialization bug in iso_stream_schedule()

Commit c3ee9b76aa93 (EHCI: improved logic for isochronous scheduling)
introduced the idea of using ehci->last_iso_frame as the origin (or
base) for the circular calculations involved in modifying the
isochronous schedule.  However, the new code it added used
ehci->last_iso_frame before the value was properly initialized.  This
patch rectifies the mistake by moving the initialization lines earlier
in iso_stream_schedule().

This fixes Bugzilla #72891.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Fixes: c3ee9b76aa93
Reported-by: Joe Bryant <tenminjoe@yahoo.com>
Tested-by: Joe Bryant <tenminjoe@yahoo.com>
Tested-by: Martin Long <martin@longhome.co.uk>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index e113fd73aeae..c399606f154e 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1581,6 +1581,10 @@ iso_stream_schedule (
         else
                 next = (now + 2 + 7) & ~0x07;   /* full frame cache */
 
+        /* If needed, initialize last_iso_frame so that this URB will be seen */
+        if (ehci->isoc_count == 0)
+                ehci->last_iso_frame = now >> 3;
+
         /*
          * Use ehci->last_iso_frame as the base.  There can't be any
          * TDs scheduled for earlier than that.
@@ -1671,10 +1675,6 @@ iso_stream_schedule (
         urb->start_frame = start & (mod - 1);
         if (!stream->highspeed)
                 urb->start_frame >>= 3;
-
-        /* Make sure scan_isoc() sees these */
-        if (ehci->isoc_count == 0)
-                ehci->last_iso_frame = now >> 3;
         return status;
 
  fail: