mirror of
https://gitlab.com/libvirt/libvirt.git
synced 2024-12-28 08:35:22 +00:00
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.
58320848d2
This patch resolves: https://bugzilla.redhat.com/show_bug.cgi?id=871201
If libvirt is restarted after updating the dnsmasq or radvd packages,
a subsequent "virsh net-destroy" will fail to kill the dnsmasq/radvd
process.
The problem is that when libvirtd restarts, it re-reads the dnsmasq
and radvd pidfiles, then does a sanity check on each pid it finds,
including checking that the symbolic link in /proc/$pid/exe actually
points to the same file as the path used by libvirt to execute the
binary in the first place. If this fails, libvirt assumes that the
process is no longer alive.
But if the original binary has been replaced, the link in /proc is set
to "$binarypath (deleted)" (it literally has the string " (deleted)"
appended to the link text stored in the filesystem), so even if a new
binary exists in the same location, attempts to resolve the link will
fail.
In the end, not only is the old dnsmasq/radvd not terminated when the
network is stopped, but a new dnsmasq can't be started when the
network is later restarted (because the original process is still
listening on the ports that the new process wants).
The solution is, when the initial "use stat to check for identical
inodes" check for identity between /proc/$pid/exe and $binpath fails,
to check /proc/$pid/exe for a link ending with " (deleted)" and if so,
truncate that part of the link and compare what's left with the
original binarypath.
A twist to this problem is that on systems with "merged" /sbin and
/usr/sbin (i.e. /sbin is really just a symlink to /usr/sbin; Fedora
17+ is an example of this), libvirt may have started the process using
one path, but /proc/$pid/exe lists a different path (indeed, on F17
this is the case - libvirtd uses /sbin/dnsmasq, but /proc/$pid/exe
shows "/usr/sbin/dnsmasq"). The further bit of code to resolve this is
to call virFileResolveAllLinks() on both the original binarypath and
on the truncated link we read from /proc/$pid/exe, and compare the
results.
The resulting code still succeeds in all the same cases it did before,
but also succeeds if the binary was deleted or replaced after it was
started.
(cherry picked from commit
|
||
|---|---|---|
| .gnulib@b4938324b7 | ||
| build-aux | ||
| daemon | ||
| docs | ||
| examples | ||
| gnulib | ||
| include | ||
| m4 | ||
| po | ||
| python | ||
| src | ||
| tests | ||
| tools | ||
| .dir-locals.el | ||
| .gitignore | ||
| .gitmodules | ||
| .mailmap | ||
| AUTHORS.in | ||
| autobuild.sh | ||
| autogen.sh | ||
| bootstrap | ||
| bootstrap.conf | ||
| cfg.mk | ||
| ChangeLog-old | ||
| configure.ac | ||
| COPYING.LIB | ||
| HACKING | ||
| libvirt.pc.in | ||
| libvirt.spec.in | ||
| Makefile.am | ||
| Makefile.nonreentrant | ||
| mingw-libvirt.spec.in | ||
| README | ||
| README-hacking | ||
| run.in | ||
| TODO | ||
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>