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6ed7374c5a
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Matthias Bolte 6ed7374c5a Fix xen driver refcounting. 
The commit cb51aa48a7 "Fix up connection
reference counting." changed the driver closing and virConnectPtr
unref-logic in virConnectClose().

Before this commit virConnectClose() closed all drivers of the given
virConnectPtr and virUnrefConnect()'ed it afterwards. After this
commit the driver-closing is done in virUnrefConnect() if and only if
the ref-count of the virConnectPtr dropped to zero.

This change in execution order leads to a virConnectPtr leak, at least
for connections to Xen.

The relevant call sequences:

virConnectOpen() -> xenUnifiedOpen() ...

... xenInotifyOpen() -> virConnectRef(conn)

... xenStoreOpen() -> xenStoreAddWatch() -> conn->refs++

virConnectClose() -> xenUnifiedClose() ...

... xenInotifyClose() -> virUnrefConnect(conn)

... xenStoreClose() -> xenStoreRemoveWatch() -> virUnrefConnect(conn)

Before the commit this additional virConnectRef/virUnrefConnect calls
where no problem, because virConnectClose() closed the drivers
explicitly and the additional refs added by the Xen subdrivers were
removed properly. After the commit this additional refs result in a
virConnectPtr leak (including a leak of the hypercall file handle;
that's how I noticed this problem), because now the drivers are only
close if and only if the ref-count drops to zero, but this cannot
happen anymore, because the additional refs from the Xen subdrivers
would only be removed if the drivers get closed, but that doesn't
happen because the ref-count cannot drop to zero.

The fix for this problem is simple: remove the
virConnectRef/virUnrefConnect calls from the Xen subdrivers (see
attached patch). Maybe someone could explain why the Xen Inotify and
Xen Store driver do this extra ref-counting, but none of the other Xen
subdrivers. It seems unnecessary to me and can be removed without
problems.

Signed-off-by: Chris Lalancette <clalance@redhat.com>
2009-09-22 15:12:48 +02:00
..
conf lxc: suspend/resume support 2009-09-22 11:30:06 +01:00
esx Fix up comments for domainXML{To,From}Native. 2009-09-21 18:15:41 +02:00
interface Move netcf interface driver into src/interface/ 2009-09-21 14:41:44 +01:00
lxc lxc: suspend/resume support 2009-09-22 11:30:06 +01:00
network Move config files to align with driver sources 2009-09-21 14:41:45 +01:00
node_device Move node device drivers to src/node_device/ 2009-09-21 14:41:43 +01:00
opennebula Move LXC driver into src/lxc/ 2009-09-21 14:41:42 +01:00
openvz OpenVZ Fix a restriction about domain names 2009-09-22 12:19:09 +02:00
phyp Fix up comments for domainXML{To,From}Native. 2009-09-21 18:15:41 +02:00
qemu prevent attempt to call cat -c during virDomainSave to raw 2009-09-22 08:56:39 +02:00
remote Remove an unnecessary variable from remoteIOReadMessage(). 2009-09-21 18:15:13 +02:00
secret Move secret driver into src/secret/ 2009-09-21 14:41:44 +01:00
security Move security drivers to src/security/ 2009-09-21 14:41:44 +01:00
storage Move node device drivers to src/node_device/ 2009-09-21 14:41:43 +01:00
test Fix up comments for domainXML{To,From}Native. 2009-09-21 18:15:41 +02:00
uml Fix up comments for domainXML{To,From}Native. 2009-09-21 18:15:41 +02:00
util lxc: suspend/resume support 2009-09-22 11:30:06 +01:00
vbox Fix up comments for domainXML{To,From}Native. 2009-09-21 18:15:41 +02:00
xen Fix xen driver refcounting. 2009-09-22 15:12:48 +02:00
.gitignore Move virsh into tools/ directory 2009-09-21 14:41:45 +01:00
datatypes.c Add usage type/id as a public API property of virSecret 2009-09-14 17:49:33 +01:00
datatypes.h Add usage type/id as a public API property of virSecret 2009-09-14 17:49:33 +01:00
driver.c Log dlopen() errors more verbosely 2009-05-08 10:05:56 +00:00
driver.h Add usage type/id as a public API property of virSecret 2009-09-14 17:49:33 +01:00
gnutls_1_0_compat.h Enable the <config.h>-requiring test; fix violations 2008-01-29 18:15:54 +00:00
internal.h infra: define ATTRIBUTE_NONNULL to mark non-NULL parameters 2009-09-03 18:04:23 +02:00
libvirt_bridge.syms Support networking in UML driver 2009-06-03 11:13:33 +00:00
libvirt_driver_modules.syms Move --with-driver-modules symbols into a separate sym file 2009-01-05 14:06:41 +00:00
libvirt_internal.h Mask out flags used internally for virSecretGetValue 2009-09-10 15:54:54 +01:00
libvirt_linux.syms migrate linux-specific symbol names into their own sym file 2009-01-05 14:08:26 +00:00
libvirt_private.syms lxc: suspend/resume support 2009-09-22 11:30:06 +01:00
libvirt_public.syms Release of libvirt 0.7.1 2009-09-15 14:24:51 +02:00
libvirt.c Don't do virSetConnError when virDrvSupportsFeature is successful. 2009-09-21 18:16:00 +02:00
Makefile.am Move remote protocol definition into src/remote/ 2009-09-21 14:41:47 +01:00
nodeinfo.c remove all trailing blank lines 2009-07-16 15:06:42 +02:00
nodeinfo.h Generic shared impls of all NUMA apis 2009-06-03 13:28:02 +00:00
README Add a README file to src/ explaining the directory structure 2009-09-21 14:41:47 +01:00

README 

       libvirt library code README
       ===========================

The directory provides the bulk of the libvirt codebase. Everything
except for the libvirtd daemon and client tools. The build uses a
large number of libtool convenience libraries - one for each child
directory, and then links them together for the final libvirt.so,
although some bits get linked directly to libvirtd daemon instead.

The files directly in this directory are supporting the public API
entry points & data structures.

There are two core shared modules to be aware of:

 * util/  - a collection of shared APIs that can be used by any
            code. This directory is always in the include path
            for all things built

 * conf/  - APIs for parsing / manipulating all the official XML
            files used by the public API. This directory is only
            in the include path for driver implementation modules


Then there are the hypervisor implementations:

 * esx/          - VMware ESX and GSX support using vSphere API over SOAP
 * lxc/          - Linux Native Containers
 * opennebula/   - Open Nebula using XMLRPC
 * openvz/       - OpenVZ containers using cli tools
 * phyp/         - IBM Power Hypervisor using CLI tools over SSH
 * qemu/         - QEMU / KVM using qemu CLI/monitor
 * remote/       - Generic libvirt native RPC client
 * test/         - A "mock" driver for testing
 * uml/          - User Mode Linux
 * vbox/         - Virtual Box using native API
 * xen/          - Xen using hypercalls, XenD SEXPR & XenStore


Finally some secondary drivers that are shared for several HVs.
Currently these are used by LXC, OpenVZ, QEMU, UML and Xen drivers.
The ESX, OpenNebula, Power Hypervisor, Remote, Test & VirtualBox
drivers all implement the secondary drivers directly

 * interface/    - Host network interface management
 * network/      - Virtual NAT networking
 * node_device/  - Host device enumeration
 * secret/       - Secret management
 * security/     - Mandatory access control drivers
 * storage/      - Storage management drivers


Since both the hypervisor and secondary drivers can be built as
dlopen()able modules, it is *FORBIDDEN* to have build dependencies
between these directories. Drivers are only allowed to depend on
the public API, and the internal APIs in the util/ and conf/
directories