mirror of
https://gitlab.uni-freiburg.de/opensourcevdi/spice
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2d1c00a659
During seamless migration, after switching host, if a client was connected during the migration, it will have data to send back to the new qemu/spice-server instance. This is handled through MIGRATE_DATA messages. SPICE char devices use such MIGRATE_DATA messages to restore their state. However, the MIGRATE_DATA message can arrive any time after the new qemu instance has started, this can happen before or after the SPICE char devices have been created. In order to handle this, if the migrate data arrives early, it's stored in reds->agent_state.mig_data, and attach_to_red_agent() will restore the agent state as appropriate. Unfortunately this does not work as expected, for main channel (agent messages). If attach_to_red_agent() is called before the MIGRATE_DATA message reaches the server, all goes well, but if MIGRATE_DATA reaches the server before attach_to_red_agent() gets called, then some assert() gets triggered in spice_char_device_state_restore(): ((null):32507): Spice-ERROR **: char_device.c:937:spice_char_device_state_restore: assertion `dev->num_clients == 1 && dev->wait_for_migrate_data' failed Thread 3 (Thread 0x7f406b543700 (LWP 32543)): Thread 2 (Thread 0x7f40697ff700 (LWP 32586)): Thread 1 (Thread 0x7f4079b45a40 (LWP 32507)): When restoring state, a client must already be added to the spice-char-device. What happens is that a client is not being added to the char-device when when MIGRATE_DATA arrives first, which leaves both dev->num_clients and dev->wait_for_migrate_data value at 0. This commit changes the logic in spice_server_char_device_add_interface(), such that if there is migrate data pending in reds->agent_state.mig_data but no client was added to the spice-char-device yet, then first the client is added to the device by calling spice_char_device_client_add(), and only then the state is restored. === How to Reproduce To reproduce, add delays to the migration connection between qmeu-kvm on the source host (SRC) and on the destination (DST). Specifically I added a man in the middle DLY host between migration ports from SRC to DST. +-----+ +-----+ +-----+ | SRC |--> | DLY | --> | DST | +-----+ +-----+ +-----+ DLY listens on port P1 (e.g. 4444) and DST listens on port PINCOMING (e.g. 4444, from qemu-kvm '-incoming' command line option) Precondition: make sure port P1 on DLY is accessible in iptables. Option 1: use ssh tcp port forwarding On DLY host run ssh: ssh DLY:P1:DST:PINCOMING DST Then use the following migration command (on qemu-kvm monitor): client_migrate_info spice DST PSPICE migrate -d tcp:DLY:P1 Option 2: Use a simple proxy program that forwards packets from SRC to DST while adding some delays. The program runs on DLY, listens to port D1, upon accept connects to DST:PINCOMING and forward all packets from DLY:D1 to DST:PINCOMING. Then use the same migrate command as in option 1: client_migrate_info spice DST PSPICE migrate -d tcp:DLY:P1 === How to Reproduce Ends This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1035184 Based-on-a-patch-by: Christophe Fergeau <cfergeau@redhat.com> |
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| client | ||
| docs | ||
| m4 | ||
| server | ||
| spice-common@b3a00f4411 | ||
| tests | ||
| tools | ||
| uncrustify_cfg | ||
| .gitignore | ||
| .gitmodules | ||
| .mailmap | ||
| AUTHORS | ||
| autogen.sh | ||
| cfg.mk | ||
| ChangeLog | ||
| configure.ac | ||
| COPYING | ||
| GNUmakefile | ||
| maint.mk | ||
| Makefile.am | ||
| NEWS | ||
| README | ||
| spice-server.pc.in | ||
| TODO.multiclient | ||
SPICE: Simple Protocol for Independent Computing Environments
=============================================================
SPICE is a remote display system built for virtual environments which
allows you to view a computing 'desktop' environment not only on the
machine where it is running, but from anywhere on the Internet and
from a wide variety of machine architectures.
Installation
------------
The SPICE package uses GNU autotools, so the build install process
follows the standard process documented in the INSTALL file. As a
quick start you can do
./configure --prefix=/usr --sysconfdir=/etc \
--localstatedir=/var --libdir=/usr/lib
make
sudo make install
Or to install into a private user specific location
./configure --prefix=$HOME/spice
make
make install
The following mandatory dependancies are required in order to
build SPICE
Spice protocol >= 0.9.0
Pixman >= 0.17.7
OpenSSL
libjpeg
zlib
Cyrus-SASL
The following optional dependancies increase the available
functionality
GE Gui >= 0.6.0, < 0.7.0 (GUI app support)
OpenGL (GUI app support)
Alsa (Linux support)
XRandR >= 1.2 (X11 support)
Xinerama >= 1.0 (X11 support)
libcacard >= 0.1.2 (Smartcard support)
Communication
-------------
To communicate with the development team, or to post patches
there is a technical mailing list:
http://lists.freedesktop.org/mailman/listinfo/spice-devel
There is also a mailing list for new release announcements:
http://lists.freedesktop.org/archives/spice-announce/
To view known bugs, or report new bugs, in SPICE visit
https://bugs.freedesktop.org/describecomponents.cgi?product=Spice
Bugs found when using an OS distribution's binary packages should
be reported to the OS vendors' own bug tracker first.
The latest SPICE code can be found in GIT at:
http://cgit.freedesktop.org/spice/
Licensing
---------
SPICE is provided under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
Please see the COPYING file for the complete LGPLv2+ license
terms, or visit <http://www.gnu.org/licenses/>.
Experimental Features
---------------------
To enable multiple client connections, set:
SPICE_DEBUG_ALLOW_MC=1
-- End of readme