If client stream does not have any data to sink and neither received
EOF, a dummy packet is sent to the daemon signalising client is ready to
sink some data. However, after we added event loop to client a race may
occur:
Thread 1 calls virNetClientStreamRecvPacket and since no data are cached
nor stream has EOF, it decides to send dummy packet to server which will
sent some data in turn. However, during this decision and actual message
exchange with server -
Thread 2 receives last stream data from server. Therefore an EOF is set
on stream and if there is a call waiting (which is not yet) it is woken
up. However, Thread 1 haven't sent anything so far, so there is no call
to be woken up. So this thread sent dummy packet to daemon, which
ignores that as no stream is associated with such packet and therefore
no reply will ever come.
This race causes client to hang indefinitely.
The RPC code had several latent memory leaks and an attempt to
free the wrong string, but thankfully nothing triggered them
(blkiotune was the only one returning a string, and always as
the last parameter). Also, our cleanups for rpcgen ended up
nuking a line of code that renders VIR_TYPED_PARAM_INT broken,
because it was the only use of 'i' in a function, even though
it was a member usage rather than a standalone declaration.
* daemon/remote.c (remoteSerializeTypedParameters): Free the
correct array element.
(remoteDispatchDomainGetSchedulerParameters)
(remoteDispatchDomainGetSchedulerParametersFlags)
(remoteDispatchDomainBlockStatsFlags)
(remoteDispatchDomainGetMemoryParameters): Don't leak strings.
* src/rpc/genprotocol.pl: Don't nuke member-usage of 'buf' or 'i'.
When one thread passes the buck to another thread, it uses
virCondSignal to wake up the target thread. The variable
'haveTheBuck' is not updated in a race-free manner when
this occurs. The current thread sets it to false, and the
woken up thread sets it to true. There is a window where
a 3rd thread can come in and grab the buck.
Even if this didn't lead to crashes & deadlocks, this would
still result in unfairness in the buckpassing algorithm.
A better solution is to *never* set haveTheBuck to false
when we're passing the buck. Only set it to false when there
is no further thread waiting for the buck.
* src/rpc/virnetclient.c: Only set haveTheBuck to false
if no thread is waiting
Commit fd06692544 tried to fix
a race condition in
commit fa9595003d
Author: Daniel P. Berrange <berrange@redhat.com>
Date: Fri Nov 11 15:28:41 2011 +0000
Explicitly track whether the buck is held in remote client
Unfortunately there is a second race condition whereby the
event loop can trigger due to incoming data to read. Revert
this fix, so a complete fix for the problem can be cleanly
applied
* src/rpc/virnetclient.c: Revert fd06692544
Currently if you try to connect to a local libvirtd when
libvirtd is not in $PATH, you'll get an error
error: internal error invalid use of command API
This is because remoteFindDaemonPath() returns NULL, which
causes us to pass NULL into virNetSocketConnectUNIX which
in turn causes us to pass NULL into virCommandNewArgList.
Adding missing error checks improves this to
error: internal error Unable to locate libvirtd daemon in $PATH
* src/remote/remote_driver.c: Report error if libvirtd
cannot be found
* src/rpc/virnetsocket.c: Report error if caller requested
spawning of daemon, but provided no binary path
https://bugzilla.redhat.com/show_bug.cgi?id=648855 mentioned a
misuse of 'an' where 'a' is proper; that has since been fixed,
but a search found other problems (some were a spelling error for
'and', while most were fixed by 'a').
* daemon/stream.c: Fix grammar.
* src/conf/domain_conf.c: Likewise.
* src/conf/domain_event.c: Likewise.
* src/esx/esx_driver.c: Likewise.
* src/esx/esx_vi.c: Likewise.
* src/rpc/virnetclient.c: Likewise.
* src/rpc/virnetserverprogram.c: Likewise.
* src/storage/storage_backend_fs.c: Likewise.
* src/util/conf.c: Likewise.
* src/util/dnsmasq.c: Likewise.
* src/util/iptables.c: Likewise.
* src/xen/xen_hypervisor.c: Likewise.
* src/xen/xend_internal.c: Likewise.
* src/xen/xs_internal.c: Likewise.
* tools/virsh.c: Likewise.
The RPC fixups needed on Linux are also needed on cygwin, and
worked without further tweaking to the list of fixups. Also,
unlike BSD, Cygwin exports 'struct ifreq', but unlike Linux,
Cygwin lacks the ioctls that we were using 'struct ifreq' to
access. This patch allows compilation under cygwin.
* src/rpc/genprotocol.pl: Also perform fixups on cygwin.
* src/util/virnetdev.c (HAVE_STRUCT_IFREQ): Also require AF_PACKET
definition.
* src/util/virnetdevbridge.c (virNetDevSetupControlFull): Only
compile if SIOCBRADDBR works.
Originaly, the code checked if another client is the queue and infered
ownership of the buck from that. Commit fa9595003d
added a separate variable to track the buck. That caused, that a new
call might enter claiming it has the buck, while another thread was
signalled to take the buck. This ends in two threads claiming they hold
the buck and entering poll(). This happens due to a race on waking up
threads on the client lock mutex.
This caused multi-threaded clients to hang, most prominently visible and
reproducible on python based clients, like virt-manager.
This patch causes threads, that have been signalled to take the buck to
re-check if buck is held by another thread.
Detected by Coverity. Leak introduced in commit 673adba.
Two separate bugs here:
1. call was not freed on all error paths
2. virCondDestroy was called even if virCondInit failed
Signed-off-by: Alex Jia <ajia@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
When another thread was dispatching while we wanted to send a
non-blocking call, we correctly queued the call and woke up the thread
but the thread just threw the call away since it forgot to recheck if
its socket was writable.
When spawning an ssh connection, the environment variables
DISPLAY, SSH_ASKPASS, ... are passed. However XAUTHORITY,
which is necessary if the .Xauthority is in a non default
place, was not passed.
Signed-off-by: Christian Franke <nobody@nowhere.ws>
The keepalive program has two procedures: PING, and PONG.
Both are used only in asynchronous messages and the sender doesn't wait
for any reply. However, the party which receives PING messages is
supposed to react by sending PONG message the other party, but no
explicit binding between PING and PONG messages is made. For backward
compatibility neither server nor client are allowed to send keepalive
messages before checking that remote party supports them.
When virNetClientIOEventLoop is called for a non-blocking call and not
even a single byte can be sent from this call without blocking, we
properly reported that to the caller which properly frees the call. But
we never removed the call from a call queue.
Due to the asynchronous nature of streams, we might continue to
receive some stream packets from the server even after we have
shutdown the stream on the client side. These should be discarded
silently, rather than raising an error in the RPC layer.
* src/rpc/virnetclient.c: Discard stream data silently
Add a new virNetClientSendNonBlock which returns 2 on
full send, 1 on partial send, 0 on no send, -1 on error
If a partial send occurs, then a subsequent call to any
of the virNetClientSend* APIs will finish any outstanding
I/O.
TODO: the virNetClientEvent event handler could be used
to speed up completion of partial sends if an event loop
is present.
* src/rpc/virnetsocket.h, src/rpc/virnetsocket.c: Add new
virNetSocketHasPendingData() API to test for cached
data pending send.
* src/rpc/virnetclient.c, src/rpc/virnetclient.h: Add new
virNetClientSendNonBlock() API to send non-blocking API
Stop multiplexing virNetClientSend for two different purposes,
instead add virNetClientSendWithReply and virNetClientSendNoReply
* src/rpc/virnetclient.c, src/rpc/virnetclient.h: Replace
virNetClientSend with virNetClientSendWithReply and
virNetClientSendNoReply
* src/rpc/virnetclientprogram.c, src/rpc/virnetclientstream.c:
Update for new API names
Remove some duplication by pulling the code for passing the
buck out into a helper method
* src/rpc/virnetclient.c: Introduce virNetClientIOEventLoopPassTheBuck
Instead of inferring whether the buck is held from the waitDispatch
pointer, use an explicit 'bool haveTheBuck' field
* src/rpc/virnetclient.c: Explicitly track the buck
Directly messing around with the linked list is potentially
dangerous. Introduce some helper APIs to deal with list
manipulating the list
* src/rpc/virnetclient.c: Create linked list handlers
The src/util/network.c file is a dumping ground for many different
APIs. Split it up into 5 pieces, along functional lines
- src/util/virnetdevbandwidth.c: virNetDevBandwidth type & helper APIs
- src/util/virnetdevvportprofile.c: virNetDevVPortProfile type & helper APIs
- src/util/virsocketaddr.c: virSocketAddr and APIs
- src/conf/netdev_bandwidth_conf.c: XML parsing / formatting
for virNetDevBandwidth
- src/conf/netdev_vport_profile_conf.c: XML parsing / formatting
for virNetDevVPortProfile
* src/util/network.c, src/util/network.h: Split into 5 pieces
* src/conf/netdev_bandwidth_conf.c, src/conf/netdev_bandwidth_conf.h,
src/conf/netdev_vport_profile_conf.c, src/conf/netdev_vport_profile_conf.h,
src/util/virnetdevbandwidth.c, src/util/virnetdevbandwidth.h,
src/util/virnetdevvportprofile.c, src/util/virnetdevvportprofile.h,
src/util/virsocketaddr.c, src/util/virsocketaddr.h: New pieces
* daemon/libvirtd.h, daemon/remote.c, src/conf/domain_conf.c,
src/conf/domain_conf.h, src/conf/network_conf.c,
src/conf/network_conf.h, src/conf/nwfilter_conf.h,
src/esx/esx_util.h, src/network/bridge_driver.c,
src/qemu/qemu_conf.c, src/rpc/virnetsocket.c,
src/rpc/virnetsocket.h, src/util/dnsmasq.h, src/util/interface.h,
src/util/iptables.h, src/util/macvtap.c, src/util/macvtap.h,
src/util/virnetdev.h, src/util/virnetdevtap.c,
tools/virsh.c: Update include files
Send and receive string typed parameters across RPC. This also
completes the back-compat mentioned in the previous patch - the
only time we have an older client talking to a newer server is
if RPC is in use, so filtering out strings during RPC prevents
returning an unknown type to the older client.
* src/remote/remote_protocol.x (remote_typed_param_value): Add
another union value.
* daemon/remote.c (remoteDeserializeTypedParameters): Handle
strings on rpc.
(remoteSerializeTypedParameters): Likewise; plus filter out
strings when replying to older clients. Adjust callers.
* src/remote/remote_driver.c (remoteFreeTypedParameters)
(remoteSerializeTypedParameters)
(remoteDeserializeTypedParameters): Handle strings on rpc.
* src/rpc/gendispatch.pl: Properly clean up typed arrays.
* src/remote_protocol-structs: Update.
Based on an initial patch by Hu Tao, with feedback from
Daniel P. Berrange.
Signed-off-by: Eric Blake <eblake@redhat.com>
The socket address APIs in src/util/network.h either take the
form virSocketAddrXXX, virSocketXXX or virSocketXXXAddr.
Sanitize this so everything is virSocketAddrXXXX, and ensure
that the virSocketAddr parameter is always the first one.
* src/util/network.c, src/util/network.h: Santize socket
address API naming
* src/conf/domain_conf.c, src/conf/network_conf.c,
src/conf/nwfilter_conf.c, src/network/bridge_driver.c,
src/nwfilter/nwfilter_ebiptables_driver.c,
src/nwfilter/nwfilter_learnipaddr.c,
src/qemu/qemu_command.c, src/rpc/virnetsocket.c,
src/util/dnsmasq.c, src/util/iptables.c,
src/util/virnetdev.c, src/vbox/vbox_tmpl.c: Update for
API renaming
The code calling sendfd/recvfd was mistakenly assuming those
calls would never block. They can in fact return EAGAIN and
this is causing us to drop the client connection when blocking
ocurrs while sending/receiving FDs.
Fixing this is a little hairy on the incoming side, since at
the point where we see the EAGAIN, we already thought we had
finished receiving all data for the packet. So we play a little
trick to reset bufferOffset again and go back into polling for
more data.
* src/rpc/virnetsocket.c, src/rpc/virnetsocket.h: Update
virNetSocketSendFD/RecvFD to return 0 on EAGAIN, or 1
on success
* src/rpc/virnetclient.c: Move decoding of header & fds
out of virNetClientCallDispatch and into virNetClientIOHandleInput.
Handling blocking when sending/receiving FDs
* src/rpc/virnetmessage.h: Add a 'donefds' field to track
how many FDs we've sent / received
* src/rpc/virnetserverclient.c: Handling blocking when
sending/receiving FDs
I ran into the following build failure:
$ mkdir -p build1 build2/a/very/deep/hierarcy
$ cd build2/a/very/deep/hierarcy
$ ../../../../../configure && make
$ cd ../../../../build1
$ ../configure && make
...
../../src/remote/remote_protocol.c:7:55: fatal error: ../../../../../src/remote/remote_protocol.h: No such file or directory
Turns out that we were sometimes generating the remote_protocol.c
file with information from the VPATH build, which is bad, since
any file shipped in the tarball should be idempotent no matter how
deep the VPATH build tree that created it.
* src/rpc/genprotocol.pl: Don't embed VPATH into generated file.
If daemon is using SASL it reads client data into a cache. This cache is
big (usually 65KB) and can thus contain 2 or more messages. However,
on socket event we can dispatch only one message. So if we read two
messages at once, the second will not be dispatched as the socket event
goes away with filling the cache.
Moreover, when dispatching the cache we need to remember to take care
of client max requests limit.
The RPC server classes are extended to allow FDs to be received
from clients with calls. There is not currently any way for a
procedure to pass FDs back to the client with replies
* daemon/remote.c, src/rpc/gendispatch.pl: Change virNetMessageHeaderPtr
param to virNetMessagePtr in dispatcher impls
* src/rpc/virnetserver.c, src/rpc/virnetserverclient.c,
src/rpc/virnetserverprogram.c, src/rpc/virnetserverprogram.h:
Extend to support FD passing
Extend the RPC client code to allow file descriptors to be sent
to the server with calls, and received back with replies.
* src/remote/remote_driver.c: Stub extra args
* src/libvirt_private.syms, src/rpc/virnetclient.c,
src/rpc/virnetclient.h, src/rpc/virnetclientprogram.c,
src/rpc/virnetclientprogram.h: Extend APIs to allow
FD passing
Define two new RPC message types VIR_NET_CALL_WITH_FDS and
VIR_NET_REPLY_WITH_FDS. These message types are equivalent
to VIR_NET_CALL and VIR_NET_REPLY, except that between the
message header, and payload there is a 32-bit integer field
specifying how many file descriptors have been passed.
The actual file descriptors are sent/recv'd out of band.
* src/rpc/virnetmessage.c, src/rpc/virnetmessage.h,
src/libvirt_private.syms: Add support for handling
passed file descriptors
* src/rpc/virnetprotocol.x: Extend protocol for FD
passing
Add APIs to the virNetSocket object, to allow file descriptors
to be sent/received over UNIX domain socket connections
* src/rpc/virnetsocket.c, src/rpc/virnetsocket.h,
src/libvirt_private.syms: Add APIs for FD send/recv
The libvirtd daemon had a few crude system tap probes. Some of
these were broken during the RPC rewrite. The new modular RPC
code is structured in a way that allows much more effective
tracing. Instead of trying to hook up the original probes,
define a new set of probes for the RPC and event code.
The master probes file is now src/probes.d. This contains
probes for virNetServerClientPtr, virNetClientPtr, virSocketPtr
virNetTLSContextPtr and virNetTLSSessionPtr modules. Also add
probes for the poll event loop.
The src/dtrace2systemtap.pl script can convert the probes.d
file into a libvirt_probes.stp file to make use from systemtap
much simpler.
The src/rpc/gensystemtap.pl script can generate a set of
systemtap functions for translating RPC enum values into
printable strings. This works for all RPC header enums (program,
type, status, procedure) and also the authentication enum
The PROBE macro will automatically generate a VIR_DEBUG
statement, so any place with a PROBE can remove any existing
manual DEBUG statements.
* daemon/libvirtd.stp, daemon/probes.d: Remove obsolete probing
* daemon/libvirtd.h: Remove probe macros
* daemon/Makefile.am: Remove all probe buildings/install
* daemon/remote.c: Update authentication probes
* src/dtrace2systemtap.pl, src/rpc/gensystemtap.pl: Scripts
to generate STP files
* src/internal.h: Add probe macros
* src/probes.d: Master list of probes
* src/rpc/virnetclient.c, src/rpc/virnetserverclient.c,
src/rpc/virnetsocket.c, src/rpc/virnettlscontext.c,
src/util/event_poll.c: Insert probe points, removing any
DEBUG statements that duplicate the info
Pull the call to gnutls_x509_crt_get_dn up into a higher function
so that the 'dname' variable will be available for probe points
* src/rpc/virnettlscontext.c: Pull gnutls_x509_crt_get_dn up
one level
If we receive an error on the stream, set the EOF marker so
that any further (bogus) incoming data is dropped.
* src/rpc/virnetclientstream.c: Set EOF on stream
If we send back an unknown program error for async messages,
we will confuse the client because they only expect replies
for method calls. Just log & drop any invalid async messages
* src/rpc/virnetserver.c: Don't send error for async messages
Commit 597fe3cee6 accidentally
introduced a deadlock when reporting an unknown RPC program.
The virNetServerDispatchNewMessage method is called with
the client locked, and must therefore not attempt to send
any RPC messages back to the client. Only once the incoming
message is passed off to the virNetServerHandleJob worker
is it safe to start sending messages back
* src/rpc/virnetserver.c: Delay checking for unknown RPC
program until in worker thread
Do not crash if virStreamFinish is called after error.
==11000== Invalid read of size 4
==11000== at 0x373A8099A0: pthread_mutex_lock (pthread_mutex_lock.c:51)
==11000== by 0x4C7CADE: virMutexLock (threads-pthread.c:85)
==11000== by 0x4D57C31: virNetClientStreamRaiseError (virnetclientstream.c:203)
==11000== by 0x4D385E4: remoteStreamFinish (remote_driver.c:3541)
==11000== by 0x4D182F9: virStreamFinish (libvirt.c:14157)
==11000== by 0x40FDC4: cmdScreenshot (virsh.c:3075)
==11000== by 0x42BA40: vshCommandRun (virsh.c:14922)
==11000== by 0x42ECCA: main (virsh.c:16381)
==11000== Address 0x59b86c0 is 16 bytes inside a block of size 216 free'd
==11000== at 0x4A06928: free (vg_replace_malloc.c:427)
==11000== by 0x4C69E2B: virFree (memory.c:310)
==11000== by 0x4D57B56: virNetClientStreamFree (virnetclientstream.c:184)
==11000== by 0x4D3DB7A: remoteDomainScreenshot (remote_client_bodies.h:1812)
==11000== by 0x4CFD245: virDomainScreenshot (libvirt.c:2903)
==11000== by 0x40FB73: cmdScreenshot (virsh.c:3029)
==11000== by 0x42BA40: vshCommandRun (virsh.c:14922)
==11000== by 0x42ECCA: main (virsh.c:16381)
Mostly straight-forward, although this is the first API that
returns a new snapshot based on a snapshot rather than a domain.
* src/remote/remote_protocol.x
(REMOTE_PROC_DOMAIN_SNAPSHOT_GET_PARENT): New rpc.
(remote_domain_snapshot_get_parent_args)
(remote_domain_snapshot_get_parent_ret): New structs.
* src/rpc/gendispatch.pl: Adjust generator.
* src/remote/remote_driver.c (remote_driver): Use it.
* src/remote_protocol-structs: Update.
