49cb59778a
The lookup didn't do anything apart from comparing the sysfs paths anyway since that's what makes each mdev unique. The most ridiculous usage of the old logic was in virHostdevReAttachMediatedDevices where in order to drop an mdev hostdev from the list of active devices we first had to create a new mdev and use it in the lookup call. Why couldn't we have used the hostdev directly? Because the hostdev and mdev structures are incompatible. The way mdevs are currently removed is via a write to a specific sysfs attribute. If you do it while the machine which has the mdev assigned is running, the write call may block (with a new enough kernel, with older kernels it would return a write error!) until the device is no longer in use which is when the QEMU process exits. The interesting part here comes afterwards when we're cleaning up and call virHostdevReAttachMediatedDevices. The domain doesn't exist anymore, so the list of active hostdevs needs to be updated and the respective hostdevs removed from the list, but remember we had to create an mdev object in the memory in order to find it in the list first which will fail because the write to sysfs had already removed the mdev instance from the host system. And so the next time you try to start the same domain you'll get: "Requested operation is not valid: mediated device <path> is in use by driver QEMU, domain <name>" Fixes: https://gitlab.com/libvirt/libvirt/-/issues/119 Signed-off-by: Erik Skultety <eskultet@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com>
Libvirt API for virtualization
Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
For some of these hypervisors, it provides a stateful management daemon which runs on the virtualization host allowing access to the API both by non-privileged local users and remote users.
Layered packages provide bindings of the libvirt C API into other languages including Python, Perl, PHP, Go, Java, OCaml, as well as mappings into object systems such as GObject, CIM and SNMP.
Further information about the libvirt project can be found on the website:
License
The libvirt C API is distributed under the terms of GNU Lesser General Public License, version 2.1 (or later). Some parts of the code that are not part of the C library may have the more restrictive GNU General Public License, version 2.0 (or later). See the files COPYING.LESSER and COPYING for full license terms & conditions.
Installation
Instructions on building and installing libvirt can be found on the website:
https://libvirt.org/compiling.html
Contributing
The libvirt project welcomes contributions in many ways. For most components the best way to contribute is to send patches to the primary development mailing list. Further guidance on this can be found on the website:
https://libvirt.org/contribute.html
Contact
The libvirt project has two primary mailing lists:
- libvirt-users@redhat.com (for user discussions)
- libvir-list@redhat.com (for development only)
Further details on contacting the project are available on the website: