Commit 6d89252a authored Dec 04, 2014 by Alan Stern Committed by Greg Kroah-Hartman Jan 09, 2015

USB: EHCI: fix initialization bug in iso_stream_schedule()



Commit c3ee9b76 (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: c3ee9b76
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>

parent f161ead7

drivers/usb/host/ehci-sched.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -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:

Admin message