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From: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
To: svt-core@virtuozzo.com
Cc: den@openvz.org, andrey.drobyshev@virtuozzo.com
Subject: [PATCH QEMU HCI-8.0 v3 07/12] usb-host: skip product-string read on CPR incoming #VSTOR-137800
Date: Mon, 14 Sep 2026 22:13:15 +0300	[thread overview]
Message-ID: <20260914-usb-host_v3-v3-7-c43a834ce016@virtuozzo.com> (raw)
In-Reply-To: <20260914-usb-host_v3-v3-0-c43a834ce016@virtuozzo.com>

usb_host_open() reads the product string descriptor from the device
with a synchronous control transfer.  On the CPR target this runs while
the device is being handed over, and the transfer can block there,
hanging the incoming migration.

The string only fills the cosmetic product_desc, so skip the read when
we're the CPR target and fall back to the synthetic "host:bus.addr"
name.

Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
 hw/usb/host-libusb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/usb/host-libusb.c b/hw/usb/host-libusb.c
index 77ee3ca1dd7..922c1a5585e 100644
--- a/hw/usb/host-libusb.c
+++ b/hw/usb/host-libusb.c
@@ -1064,7 +1064,7 @@ static int usb_host_open(USBHostDevice *s, libusb_device *dev, int hostfd)
     udev->speed = speed_map[libusb_speed];
     usb_host_speed_compat(s);
 
-    if (s->ddesc.iProduct) {
+    if (s->ddesc.iProduct && !cpr_is_incoming()) {
         libusb_get_string_descriptor_ascii(s->dh, s->ddesc.iProduct,
                                            (unsigned char *)udev->product_desc,
                                            sizeof(udev->product_desc));

-- 
2.47.1


  parent reply	other threads:[~2026-09-14 19:13 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-14 19:13 [PATCH QEMU HCI-8.0 v3 00/12] usb-host: support CPR migration Andrey Drobyshev
2026-09-14 19:13 ` [PATCH QEMU HCI-8.0 v3 01/12] usb-host: don't leak hostdev FD on open failure #VSTOR-137800 Andrey Drobyshev
2026-09-14 19:13 ` [PATCH QEMU HCI-8.0 v3 02/12] usb-host: add migration blocker for CPR modes #VSTOR-137800 Andrey Drobyshev
2026-09-14 19:13 ` [PATCH QEMU HCI-8.0 v3 03/12] usb-host: preserve hostdev FD during CPR migration #VSTOR-137800 Andrey Drobyshev
2026-09-14 19:13 ` [PATCH QEMU HCI-8.0 v3 04/12] usb-host: factor out usb_host_reap_xfers() #VSTOR-137800 Andrey Drobyshev
2026-09-14 19:13 ` [PATCH QEMU HCI-8.0 v3 05/12] usb-host: drain in-flight URBs across CPR #VSTOR-137800 Andrey Drobyshev
2026-09-14 19:13 ` [PATCH QEMU HCI-8.0 v3 06/12] usb-host: re-issue drained URBs if CPR is aborted #VSTOR-137800 Andrey Drobyshev
2026-09-14 19:13 ` Andrey Drobyshev [this message]
2026-09-14 19:13 ` [PATCH QEMU HCI-8.0 v3 08/12] usb-host: hand off the device across cpr-transfer #VSTOR-137800 Andrey Drobyshev
2026-09-14 19:13 ` [PATCH QEMU HCI-8.0 v3 09/12] usb: migrate the interface altsetting #VSTOR-137800 Andrey Drobyshev
2026-09-14 19:13 ` [PATCH QEMU HCI-8.0 v3 10/12] usb-host: reconfigure endpoints on CPR incoming #VSTOR-137800 Andrey Drobyshev
2026-09-14 19:13 ` [PATCH QEMU HCI-8.0 v3 11/12] hcd-xhci: resync isochronous endpoints after CPR #VSTOR-137800 Andrey Drobyshev
2026-09-14 19:13 ` [PATCH QEMU HCI-8.0 v3 12/12] usb-host: make CPR migration blocker conditional #VSTOR-137800 Andrey Drobyshev

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