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Provide README #2

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JayFoxRox opened this issue Jun 30, 2018 · 1 comment
Closed

Provide README #2

JayFoxRox opened this issue Jun 30, 2018 · 1 comment

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@JayFoxRox
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Something like I had for https://github.com/JayFoxRox/xqemu-espes
@JayFoxRox JayFoxRox mentioned this issue Jul 16, 2018
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@JayFoxRox
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Done

JayFoxRox pushed a commit that referenced this issue Sep 11, 2018
@berrange
migration: fix crash in when incoming client channel setup fails
ca273df 
The way we determine if we can start the incoming migration was
changed to use migration_has_all_channels() in:

  commit 428d890
  Author: Juan Quintela <quintela@redhat.com>
  Date:   Mon Jul 24 13:06:25 2017 +0200

    migration: Create migration_has_all_channels

This method in turn calls multifd_recv_all_channels_created()
which is hardcoded to always return 'true' when multifd is
not in use. This is a latent bug...

...activated in a following commit where that return result
ends up acting as the flag to indicate whether it is possible
to start processing the migration:

  commit 36c2f8b
  Author: Juan Quintela <quintela@redhat.com>
  Date:   Wed Mar 7 08:40:52 2018 +0100

    migration: Delay start of migration main routines

This means that if channel initialization fails with normal
migration, it'll never notice and attempt to start the
incoming migration regardless and crash on a NULL pointer.

This can be seen, for example, if a client connects to a server
requiring TLS, but has an invalid x509 certificate:

qemu-system-x86_64: The certificate hasn't got a known issuer
qemu-system-x86_64: migration/migration.c:386: process_incoming_migration_co: Assertion `mis->from_src_file' failed.

 #0  0x00007fffebd24f2b in raise () at /lib64/libc.so.6
 #1  0x00007fffebd0f561 in abort () at /lib64/libc.so.6
 #2  0x00007fffebd0f431 in _nl_load_domain.cold.0 () at /lib64/libc.so.6
 #3  0x00007fffebd1d692 in  () at /lib64/libc.so.6
 #4  0x0000555555ad027e in process_incoming_migration_co (opaque=<optimized out>) at migration/migration.c:386
 #5  0x0000555555c45e8b in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>) at util/coroutine-ucontext.c:116
 #6  0x00007fffebd3a6a0 in __start_context () at /lib64/libc.so.6
 #7  0x0000000000000000 in  ()

To handle the non-multifd case, we check whether mis->from_src_file
is non-NULL. With this in place, the migration server drops the
rejected client and stays around waiting for another, hopefully
valid, client to arrive.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20180619163552.18206-1-berrange@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
JayFoxRox pushed a commit that referenced this issue Sep 11, 2018
@elmarco
monitor: temporary fix for dead-lock on event recursion
9a10540 
With a Spice port chardev, it is possible to reenter
monitor_qapi_event_queue() (when the client disconnects for
example). This will dead-lock on monitor_lock.

Instead, use some TLS variables to check for recursion and queue the
events.

Fixes:
 (gdb) bt
 #0  0x00007fa69e7217fd in __lll_lock_wait () at /lib64/libpthread.so.0
 #1  0x00007fa69e71acf4 in pthread_mutex_lock () at /lib64/libpthread.so.0
 #2  0x0000563303567619 in qemu_mutex_lock_impl (mutex=0x563303d3e220 <monitor_lock>, file=0x5633036589a8 "/home/elmarco/src/qq/monitor.c", line=645) at /home/elmarco/src/qq/util/qemu-thread-posix.c:66
 #3  0x0000563302fa6c25 in monitor_qapi_event_queue (event=QAPI_EVENT_SPICE_DISCONNECTED, qdict=0x56330602bde0, errp=0x7ffc6ab5e728) at /home/elmarco/src/qq/monitor.c:645
 #4  0x0000563303549aca in qapi_event_send_spice_disconnected (server=0x563305afd630, client=0x563305745360, errp=0x563303d8d0f0 <error_abort>) at qapi/qapi-events-ui.c:149
 #5  0x00005633033e600f in channel_event (event=3, info=0x5633061b0050) at /home/elmarco/src/qq/ui/spice-core.c:235
 #6  0x00007fa69f6c86bb in reds_handle_channel_event (reds=<optimized out>, event=3, info=0x5633061b0050) at reds.c:316
 #7  0x00007fa69f6b193b in main_dispatcher_self_handle_channel_event (info=0x5633061b0050, event=3, self=0x563304e088c0) at main-dispatcher.c:197
 #8  0x00007fa69f6b193b in main_dispatcher_channel_event (self=0x563304e088c0, event=event@entry=3, info=0x5633061b0050) at main-dispatcher.c:197
 #9  0x00007fa69f6d0833 in red_stream_push_channel_event (s=s@entry=0x563305ad8f50, event=event@entry=3) at red-stream.c:414
 #10 0x00007fa69f6d086b in red_stream_free (s=0x563305ad8f50) at red-stream.c:388
 #11 0x00007fa69f6b7ddc in red_channel_client_finalize (object=0x563304df2360) at red-channel-client.c:347
 #12 0x00007fa6a56b7fb9 in g_object_unref () at /lib64/libgobject-2.0.so.0
 #13 0x00007fa69f6ba212 in red_channel_client_push (rcc=0x563304df2360) at red-channel-client.c:1341
 #14 0x00007fa69f68b259 in red_char_device_send_msg_to_client (client=<optimized out>, msg=0x5633059b6310, dev=0x563304e08bc0) at char-device.c:305
 #15 0x00007fa69f68b259 in red_char_device_send_msg_to_clients (msg=0x5633059b6310, dev=0x563304e08bc0) at char-device.c:305
 #16 0x00007fa69f68b259 in red_char_device_read_from_device (dev=0x563304e08bc0) at char-device.c:353
 #17 0x000056330317d01d in spice_chr_write (chr=0x563304cafe20, buf=0x563304cc50b0 "{\"timestamp\": {\"seconds\": 1532944763, \"microseconds\": 326636}, \"event\": \"SHUTDOWN\", \"data\": {\"guest\": false}}\r\n", len=111) at /home/elmarco/src/qq/chardev/spice.c:199
 #18 0x00005633034deee7 in qemu_chr_write_buffer (s=0x563304cafe20, buf=0x563304cc50b0 "{\"timestamp\": {\"seconds\": 1532944763, \"microseconds\": 326636}, \"event\": \"SHUTDOWN\", \"data\": {\"guest\": false}}\r\n", len=111, offset=0x7ffc6ab5ea70, write_all=false) at /home/elmarco/src/qq/chardev/char.c:112
 #19 0x00005633034df054 in qemu_chr_write (s=0x563304cafe20, buf=0x563304cc50b0 "{\"timestamp\": {\"seconds\": 1532944763, \"microseconds\": 326636}, \"event\": \"SHUTDOWN\", \"data\": {\"guest\": false}}\r\n", len=111, write_all=false) at /home/elmarco/src/qq/chardev/char.c:147
 #20 0x00005633034e1e13 in qemu_chr_fe_write (be=0x563304dbb800, buf=0x563304cc50b0 "{\"timestamp\": {\"seconds\": 1532944763, \"microseconds\": 326636}, \"event\": \"SHUTDOWN\", \"data\": {\"guest\": false}}\r\n", len=111) at /home/elmarco/src/qq/chardev/char-fe.c:42
 #21 0x0000563302fa6334 in monitor_flush_locked (mon=0x563304dbb800) at /home/elmarco/src/qq/monitor.c:425
 #22 0x0000563302fa6520 in monitor_puts (mon=0x563304dbb800, str=0x563305de7e9e "") at /home/elmarco/src/qq/monitor.c:468
 #23 0x0000563302fa680c in qmp_send_response (mon=0x563304dbb800, rsp=0x563304df5730) at /home/elmarco/src/qq/monitor.c:517
 #24 0x0000563302fa6905 in qmp_queue_response (mon=0x563304dbb800, rsp=0x563304df5730) at /home/elmarco/src/qq/monitor.c:538
 #25 0x0000563302fa6b5b in monitor_qapi_event_emit (event=QAPI_EVENT_SHUTDOWN, qdict=0x563304df5730) at /home/elmarco/src/qq/monitor.c:624
 #26 0x0000563302fa6c4b in monitor_qapi_event_queue (event=QAPI_EVENT_SHUTDOWN, qdict=0x563304df5730, errp=0x7ffc6ab5ed00) at /home/elmarco/src/qq/monitor.c:649
 #27 0x0000563303548cce in qapi_event_send_shutdown (guest=false, errp=0x563303d8d0f0 <error_abort>) at qapi/qapi-events-run-state.c:58
 #28 0x000056330313bcd7 in main_loop_should_exit () at /home/elmarco/src/qq/vl.c:1822
 #29 0x000056330313bde3 in main_loop () at /home/elmarco/src/qq/vl.c:1862
 #30 0x0000563303143781 in main (argc=3, argv=0x7ffc6ab5f068, envp=0x7ffc6ab5f088) at /home/elmarco/src/qq/vl.c:4644

Note that error report is now moved to the first caller, which may
receive an error for a recursed event. This is probably fine (95% of
callers use &error_abort, the rest have NULL error and ignore it)

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180731150144.14022-1-marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[*_no_recurse renamed to *_no_reenter, local variables reordered]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
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