mirror of
https://gitlab.uni-freiburg.de/opensourcevdi/spice
synced 2025-12-27 07:29:32 +00:00
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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| .. | ||
| tests | ||
| .gitignore | ||
| agent-msg-filter.c | ||
| agent-msg-filter.h | ||
| char_device.c | ||
| char_device.h | ||
| demarshallers.h | ||
| dispatcher.c | ||
| dispatcher.h | ||
| glz_encode_match_tmpl.c | ||
| glz_encode_tmpl.c | ||
| glz_encoder_config.h | ||
| glz_encoder_dictionary_protected.h | ||
| glz_encoder_dictionary.c | ||
| glz_encoder_dictionary.h | ||
| glz_encoder.c | ||
| glz_encoder.h | ||
| inputs_channel.c | ||
| inputs_channel.h | ||
| jpeg_encoder.c | ||
| jpeg_encoder.h | ||
| main_channel.c | ||
| main_channel.h | ||
| main_dispatcher.c | ||
| main_dispatcher.h | ||
| Makefile.am | ||
| migration_protocol.h | ||
| mjpeg_encoder.c | ||
| mjpeg_encoder.h | ||
| red_bitmap_utils.h | ||
| red_channel.c | ||
| red_channel.h | ||
| red_client_cache.h | ||
| red_client_shared_cache.h | ||
| red_common.h | ||
| red_dispatcher.c | ||
| red_dispatcher.h | ||
| red_memslots.c | ||
| red_memslots.h | ||
| red_parse_qxl.c | ||
| red_parse_qxl.h | ||
| red_time.h | ||
| red_worker.c | ||
| red_worker.h | ||
| reds_gl_canvas.c | ||
| reds_gl_canvas.h | ||
| reds_stream.c | ||
| reds_stream.h | ||
| reds_sw_canvas.c | ||
| reds_sw_canvas.h | ||
| reds-private.h | ||
| reds.c | ||
| reds.h | ||
| smartcard.c | ||
| smartcard.h | ||
| snd_worker.c | ||
| snd_worker.h | ||
| spice_bitmap_utils.c | ||
| spice_bitmap_utils.h | ||
| spice_image_cache.c | ||
| spice_image_cache.h | ||
| spice_server_utils.h | ||
| spice_timer_queue.c | ||
| spice_timer_queue.h | ||
| spice-experimental.h | ||
| spice-server.syms | ||
| spice.h | ||
| spicevmc.c | ||
| stat.h | ||
| zlib_encoder.c | ||
| zlib_encoder.h | ||