From 579967bea69bf1b32faee13ff76b19ba641a2618 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Wed, 31 Oct 2012 13:47:10 +0100 Subject: combined-packet: Add a workaround for Linux usbfs + live migration Older versions (anything but the latest) of Linux usbfs + libusb(x), will submit larger (bulk) transfers split into multiple 16k submissions, which means that rather then all tds getting linked into the queue in one atomic operarion they get linked in a bunch at a time, which could cause problems if: 1) We scan the queue while libusb is in the middle of submitting a split bulk transfer 2) While this bulk transfer is pending we migrate to another host. The problem is that after 2, the new host will rescan the queue and combine the packets in one large transfer, where as 1) has caused the original host to see them as 2 transfers. This patch fixes this by stopping combinging if we detect a 16k transfer with its int_req flag set. This should not adversely effect performance for other cases as: 1) Linux never sets the interrupt flag on packets other then the last 2) Windows does set the in_req flag on each td, but will submit large transfers in 20k tds thus never triggering the check Signed-off-by: Hans de Goede Signed-off-by: Gerd Hoffmann --- hw/usb/combined-packet.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'hw/usb/combined-packet.c') diff --git a/hw/usb/combined-packet.c b/hw/usb/combined-packet.c index 652bf02628..3904e71634 100644 --- a/hw/usb/combined-packet.c +++ b/hw/usb/combined-packet.c @@ -117,7 +117,7 @@ void usb_ep_combine_input_packets(USBEndpoint *ep) { USBPacket *p, *u, *next, *prev = NULL, *first = NULL; USBPort *port = ep->dev->port; - int ret; + int ret, totalsize; assert(ep->pipeline); assert(ep->pid == USB_TOKEN_IN); @@ -161,8 +161,11 @@ void usb_ep_combine_input_packets(USBEndpoint *ep) } /* Is this packet the last one of a (combined) transfer? */ + totalsize = (p->combined) ? p->combined->iov.size : p->iov.size; if ((p->iov.size % ep->max_packet_size) != 0 || !p->short_not_ok || - next == NULL) { + next == NULL || + /* Work around for Linux usbfs bulk splitting + migration */ + (totalsize == 16348 && p->int_req)) { ret = usb_device_handle_data(ep->dev, first); assert(ret == USB_RET_ASYNC); if (first->combined) { -- cgit v1.2.1