mirror of
https://gitlab.com/libvirt/libvirt.git
synced 2025-03-20 07:59:00 +00:00
540c339a25
There is one problem that causes various errors in the daemon. When domain is waiting for a job, it is unlocked while waiting on the condition. However, if that domain is for example transient and being removed in another API (e.g. cancelling incoming migration), it get's unref'd. If the first call, that was waiting, fails to get the job, it unref's the domain object, and because it was the last reference, it causes clearing of the whole domain object. However, when finishing the call, the domain must be unlocked, but there is no way for the API to know whether it was cleaned or not (unless there is some ugly temporary variable, but let's scratch that). The root cause is that our APIs don't ref the objects they are using and all use the implicit reference that the object has when it is in the domain list. That reference can be removed when the API is waiting for a job. And because each domain doesn't do its ref'ing, it results in the ugly checking of the return value of virObjectUnref() that we have everywhere. This patch changes qemuDomObjFromDomain() to ref the domain (using virDomainObjListFindByUUIDRef()) and adds qemuDomObjEndAPI() which should be the only function in which the return value of virObjectUnref() is checked. This makes all reference counting deterministic and makes the code a bit clearer. Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>