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usb-host: skip open on pending postload bh 

usb-host emulates a device unplug after live migration, because the
device state is unknown and unplug/replug makes sure the guest
re-initializes the device into a working state.  This can't be done in
post-load though, so post-load just schedules a bottom half which
executes after vmload is complete.

It can happen that the device autoscan timer hits the race window
between scheduling and running the bottom half, which in turn can
triggers an assert().

Fix that issue by just ignoring the usb_host_open() call in case the
bottom half didn't execute yet.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1572851
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20180503062932.17233-1-kraxel@redhat.com
This commit is contained in:
Gerd Hoffmann 2018-05-03 08:29:32 +02:00
parent 2392ae6bbb
commit 3280ea8ede
1 changed files with 7 additions and 0 deletions
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7
hw/usb/host-libusb.c
View File

@ -102,6 +102,7 @@ struct USBHostDevice {
/* callbacks & friends */
QEMUBH *bh_nodev;
QEMUBH *bh_postld;
bool bh_postld_pending;
Notifier exit;
/* request queues */
@ -870,6 +871,10 @@ static int usb_host_open(USBHostDevice *s, libusb_device *dev)
int rc;
Error *local_err = NULL;
if (s->bh_postld_pending) {
return -1;
}
trace_usb_host_open_started(bus_num, addr);
if (s->dh != NULL) {
@ -1528,6 +1533,7 @@ static void usb_host_post_load_bh(void *opaque)
if (udev->attached) {
usb_device_detach(udev);
}
dev->bh_postld_pending = false;
usb_host_auto_check(NULL);
}
@ -1539,6 +1545,7 @@ static int usb_host_post_load(void *opaque, int version_id)
dev->bh_postld = qemu_bh_new(usb_host_post_load_bh, dev);
}
qemu_bh_schedule(dev->bh_postld);
dev->bh_postld_pending = true;
return 0;
}