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[Qemu-devel] [PATCH 2/8] combined-packet: Add a workaround for Linux usb
From: |
Hans de Goede |
Subject: |
[Qemu-devel] [PATCH 2/8] combined-packet: Add a workaround for Linux usbfs + live migration |
Date: |
Wed, 31 Oct 2012 13:47:10 +0100 |
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 <address@hidden>
---
hw/usb/combined-packet.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/hw/usb/combined-packet.c b/hw/usb/combined-packet.c
index 652bf02..3904e71 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) {
--
1.7.12.1
- [Qemu-devel] usb input pipelining patches v3, Hans de Goede, 2012/10/31
- [Qemu-devel] [PATCH 6/8] usb-redir: Use reject rather the disconnect on bad ep info, Hans de Goede, 2012/10/31
- [Qemu-devel] [PATCH 1/8] usb: Add packet combining functions, Hans de Goede, 2012/10/31
- [Qemu-devel] [PATCH 4/8] usb-redir: Add support for input pipelining, Hans de Goede, 2012/10/31
- [Qemu-devel] [PATCH 5/8] usb-redir: Add an usbredir_setup_usb_eps() helper function, Hans de Goede, 2012/10/31
- [Qemu-devel] [PATCH 2/8] combined-packet: Add a workaround for Linux usbfs + live migration,
Hans de Goede <=
- [Qemu-devel] [PATCH 7/8] usb-redir: Allow to attach USB 2.0 devices to 1.1 host controller, Hans de Goede, 2012/10/31
- [Qemu-devel] [PATCH 3/8] usb-redir: Add support for 32 bits bulk packet length, Hans de Goede, 2012/10/31
- [Qemu-devel] [PATCH 8/8] usb-redir: Allow redirecting super speed devices to high speed controllers, Hans de Goede, 2012/10/31