[Qemu-devel] usb-storage assertions

[Andrey Korolyov]

Hello,

during regular operations within linux guest with USB EHCI frontend I
am seeing process crashes with an assert during regular operations
like dpkg install:

hw/usb/dev-storage.c:334: usb_msd_handle_reset: Assertion `s->req ==
((void *)0)' failed.

This does happen when real block backend is an USB-attached device
itself, so we are hitting some subtle race right there, because a
single change of a backend to a raw file sitting on SSD has never
triggered this block with the linux guest (but xBSD pre-reboot flush
would trigger assertion from time to time in the usb_cancel_packet()
without regarding physical backend type:

hw/usb/core.c:508: usb_cancel_packet: Assertion
`usb_packet_is_inflight(p)' failed.
)

Since the 2.2.0 which I am running is not exactly freshest one, I
could re-check with master today or tomorrow, but log for hw/usb/ has
no related commits for intentional fixes over one or another issue.

Argument set to check:
-device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x6.0x7 -device
ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x6
-device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x6.0x1
-device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x6.0x2
-drive file=/dev/sdb,if=none,id=drive-usb-disk0,format=raw -device
usb-storage,drive=drive-usb-disk0,id=usb-disk0,removable=off

Thanks for looking into this!