Commit aad3a0b5f altered virObjectEventStateQueueRemote to move
the "if (!event) return" call added in the previous commit 031eb8f6
to virObjectEventStateQueue. Neither commit altered the function
prototype which used ATTRIBUTE_NONNULL(2).
This caused Coverity build problems. Since @event is now checked,
just remove the ATTRIBUTE_NONNULL check from both prototypes.
Signed-off-by: John Ferlan <jferlan@redhat.com>
If a remote call fails during event registration (more than likely from
a network failure or remote libvirtd restart timed just right), then when
calling the virObjectEventStateDeregisterID we don't want to call the
registered @freecb function because that breaks our contract that we
would only call it after succesfully returning. If the @freecb routine
were called, it could result in a double free from properly coded
applications that free their opaque data on failure to register, as seen
in the following details:
Program terminated with signal 6, Aborted.
#0 0x00007fc45cba15d7 in raise
#1 0x00007fc45cba2cc8 in abort
#2 0x00007fc45cbe12f7 in __libc_message
#3 0x00007fc45cbe86d3 in _int_free
#4 0x00007fc45d8d292c in PyDict_Fini
#5 0x00007fc45d94f46a in Py_Finalize
#6 0x00007fc45d960735 in Py_Main
#7 0x00007fc45cb8daf5 in __libc_start_main
#8 0x0000000000400721 in _start
The double dereference of 'pyobj_cbData' is triggered in the following way:
(1) libvirt_virConnectDomainEventRegisterAny is invoked.
(2) the event is successfully added to the event callback list
(virDomainEventStateRegisterClient in
remoteConnectDomainEventRegisterAny returns 1 which means ok).
(3) when function remoteConnectDomainEventRegisterAny is hit,
network connection disconnected coincidently (or libvirtd is
restarted) in the context of function 'call' then the connection
is lost and the function 'call' failed, the branch
virObjectEventStateDeregisterID is therefore taken.
(4) 'pyobj_conn' is dereferenced the 1st time in
libvirt_virConnectDomainEventFreeFunc.
(5) 'pyobj_cbData' (refered to pyobj_conn) is dereferenced the
2nd time in libvirt_virConnectDomainEventRegisterAny.
(6) the double free error is triggered.
Resolve this by adding a @doFreeCb boolean in order to avoid calling the
freeCb in virObjectEventStateDeregisterID for any remote call failure in
a remoteConnect*EventRegister* API. For remoteConnect*EventDeregister* calls,
the passed value would be true indicating they should run the freecb if it
exists; whereas, it's false for the remote call failure path.
Patch based on the investigation and initial patch posted by
fangying <fangying1@huawei.com>.
In order to mirror a server with per-object filtering, the client
needs to track which server callbackID is servicing the client
callback. This patch introduces the notion of a serverID, as
well as the plumbing to use it for network events, although the
actual complexity of using per-object filtering in the remote
driver is deferred to a later patch.
* src/conf/object_event.h (virObjectEventStateEventID): Add parameter.
(virObjectEventStateQueueRemote, virObjectEventStateSetRemote):
New prototypes.
(virObjectEventStateRegisterID): Move...
* src/conf/object_event_private.h: ...here, and add parameter.
(_virObjectEvent): Add field.
* src/conf/network_event.h (virNetworkEventStateRegisterClient): New
prototype.
* src/conf/object_event.c (_virObjectEventCallback): Add field.
(virObjectEventStateSetRemote): New function.
(virObjectEventStateQueue): Make wrapper around...
(virObjectEventStateQueueRemote): New function.
(virObjectEventCallbackListCount): Tweak return count when remote
id matching is used.
(virObjectEventCallbackLookup, virObjectEventStateRegisterID):
Tweak registration when remote id matching will be used.
(virObjectEventNew): Default to no remote id.
(virObjectEventCallbackListAddID): Likewise, but set remote id
when one is available.
(virObjectEventCallbackListRemoveID)
(virObjectEventCallbackListMarkDeleteID): Adjust return value when
remote id was set.
(virObjectEventStateEventID): Query existing id.
(virObjectEventDispatchMatchCallback): Require matching event id.
(virObjectEventStateCallbackID): Adjust caller.
* src/conf/network_event.c (virNetworkEventStateRegisterClient): New
function.
(virNetworkEventStateRegisterID): Update caller.
* src/conf/domain_event.c (virDomainEventStateRegister)
(virDomainEventStateRegisterID): Update callers.
* src/remote/remote_driver.c
(remoteConnectNetworkEventRegisterAny)
(remoteConnectNetworkEventDeregisterAny)
(remoteConnectDomainEventDeregisterAny): Likewise.
(remoteEventQueue): Hoist earlier to avoid forward declaration,
and add parameter. Adjust all callers.
* src/libvirt_private.syms (conf/object_event.h): Drop function.
Signed-off-by: Eric Blake <eblake@redhat.com>
If a user registers for a domain event filtered to a particular
domain, but the persistent domain is offline at the time, then
the code silently failed to set up the filter. As a result,
the event fires for all domains, rather than being filtered.
Network events were immune, since they always passed an id
0 argument.
The key to this patch is realizing that
virObjectEventDispatchMatchCallback() only cared about uuid;
so refusing to create a meta for a negative id is pointless,
and in fact, malloc'ing meta at all was overkill; instead,
just directly store a uuid and a flag of whether to filter.
Note that virObjectEventPtr still needs all fields of meta,
because this is how we reconstruct a virDomainPtr inside the
dispatch handler before calling the end user's callback
pointer with the correct object, even though only the uuid
portion of meta is used in deciding whether a callback
matches the given event. So while uuid is optional for
callbacks, it is mandatory for events.
The change to testDomainCreateXMLMixed is merely on the setup
scenario (as you can't register for a domain unless it is either
running or persistent). I actually first wrote that test for
this patch, then rebased it to also cover a prior patch (commit
4221d64), but had to adjust it for that patch to use Create
instead of Define for setting up the domain long enough to
register the event in order to work around this bug. But while
the setup is changed, the main body of the test is still about
whether creation events fire as expected.
* src/conf/object_event_private.h (_virObjectEventCallback):
Replace meta with uuid and flag.
(virObjectEventCallbackListAddID): Update signature.
* src/conf/object_event.h (virObjectEventStateRegisterID):
Likewise.
* src/conf/object_event_private.h (virObjectEventNew): Document
use of name and uuid in events.
* src/conf/object_event.c (virObjectEventCallbackListAddID): Drop
arguments that don't affect filtering.
(virObjectEventCallbackListRemoveID)
(virObjectEventDispatchMatchCallback)
(virObjectEventStateRegisterID): Update clients.
* src/conf/domain_event.c (virDomainEventCallbackListAdd)
(virDomainEventStateRegisterID): Likewise.
* src/conf/network_event.c (virNetworkEventStateRegisterID):
Likewise.
* tests/objecteventtest.c (testDomainCreateXMLMixed): Enhance test.
Signed-off-by: Eric Blake <eblake@redhat.com>
While working on events, I found a number of minor issues; I'm
hoisting these to the front rather than doing it piecemeal in
the patches where I first noticed bad or missing documentation.
* src/conf/object_event.c: Fix grammar, document all parameters
of public functions, wrap some long lines.
* src/conf/object_event.h: Likewise.
* src/conf/network_event.c: Likewise.
* src/conf/domain_event.c: Likewise (except for the large number
of event creation functions).
* src/libvirt_private.cyms (conf/object_event.h): Split...
(conf/network_event.h): ...to account for new file.
Signed-off-by: Eric Blake <eblake@redhat.com>
The event namespace concept is mostly redundant information.
With the re-written dispatcher, the namespace is only used
for equality comparisons between event IDs. This can be solved
by just comparing virClassPtr instances instead.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Define the public API for (de-)registering network events
and the callbacks for receiving lifecycle events. The lifecycle
event includes a 'detail' parameter to match the domain lifecycle
event data, but this is currently unused.
The network events related code goes into its own set of internal
files src/conf/network_event.[ch]
