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On a machine without yajl headers, I was seeing random segfaults from qemumonitorjsontest (about 90% of the runs on my particular machine). The segfault was inside virClassIsDerivedFrom, which points to a case of a race leading to unreferencing a stale pointer to an object that had already been freed. I also noticed that if I got the segfault, I was seeing messages such as: 2013-02-22 16:12:37.504+0000: 19833: error : virNetSocketWriteWire:1361 : Cannot write data: Bad file descriptor which is also evidence of deferencing a stale pointer. I traced it to a race where qemuMonitorTestIO could execute late, after the main thread had already called qemuMonitorTestFree and called virNetSocketClose(test->client) but not clearing it out to NULL. Sure enough, after test->client has been closed, fd is -1, which causes an attempt to write to the socket to fail, which in turn triggers the error code of qemuMonitorTestIO that tries to re-close test->client. * tests/qemumonitortestutils.c (qemuMonitorTestIO): Don't attempt to free client again if test already quit.
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>