[libvirt] [PATCH 0/3 V2] Fix race in qemu driver wrt vnc port allocation

Sorry for the delay ... V2 changes noted in the patches. The qemu driver contains a subtle race in the logic to find next available vnc port. Currently it iterates through all available ports and returns the first for which bind(2) succeeds. However it is possible that a previously issued port has not yet been bound by qemu, resulting in the same port used for a subsequent domain. The issue was briefly discussed on IRC and the consensus there was to track port allocation with a bitmap. The first patch adds some simple bitmap operations to utils. Second patch defines VNC_PORT_{MIN,MAX} and uses them in place of explicit values. Third patch makes use of the bitmap impl to track vnc port allocations. The race was consistently encountered in HA environments [1]. This patch series has been successfully tested in such environment. [1] http://www.linux-ha.org/wiki/VirtualDomain_%28resource_agent%29#VNC_port_... Jim Fehlig (3): Add simple bitmap operations to utils Add defines for QEMU_VNC_PORT_{MIN,MAX} and use them Fix race in finding available vnc port cfg.mk | 1 + src/Makefile.am | 1 + src/libvirt_private.syms | 8 +++ src/qemu/qemu_conf.h | 3 + src/qemu/qemu_driver.c | 39 +++++++++++- src/util/bitmap.c | 155 ++++++++++++++++++++++++++++++++++++++++++++++ src/util/bitmap.h | 60 ++++++++++++++++++ 7 files changed, 264 insertions(+), 3 deletions(-) create mode 100644 src/util/bitmap.c create mode 100644 src/util/bitmap.h