[Qemu-commits] [qemu/qemu] 9a1054: monitor: temporary fix for dead-lock on event recu...

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/qemu/qemu
  Commit: 9a1054061c62311f6efcd88e4df0aa5203c7b39a
      
https://github.com/qemu/qemu/commit/9a1054061c62311f6efcd88e4df0aa5203c7b39a
  Author: Marc-André Lureau <address@hidden>
  Date:   2018-07-31 (Tue, 31 Jul 2018)

  Changed paths:
    M monitor.c

  Log Message:
  -----------
  monitor: temporary fix for dead-lock on event recursion

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, 
address@hidden, info=0x5633061b0050) at main-dispatcher.c:197
 #9  0x00007fa69f6d0833 in red_stream_push_channel_event (address@hidden, 
address@hidden) 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 <address@hidden>
Message-Id: <address@hidden>
Reviewed-by: Markus Armbruster <address@hidden>
[*_no_recurse renamed to *_no_reenter, local variables reordered]
Signed-off-by: Markus Armbruster <address@hidden>


  Commit: b89041647422e2a8989ab1d521dd11f3e1eb5d20
      
https://github.com/qemu/qemu/commit/b89041647422e2a8989ab1d521dd11f3e1eb5d20
  Author: Peter Maydell <address@hidden>
  Date:   2018-07-31 (Tue, 31 Jul 2018)

  Changed paths:
    M monitor.c

  Log Message:
  -----------
  Merge remote-tracking branch 'remotes/armbru/tags/pull-monitor-2018-07-31' 
into staging

Monitor patches for 2018-07-31 (3.0.0-rc3)

# gpg: Signature made Tue 31 Jul 2018 16:46:16 BST
# gpg:                using RSA key 3870B400EB918653
# gpg: Good signature from "Markus Armbruster <address@hidden>"
# gpg:                 aka "Markus Armbruster <address@hidden>"
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-monitor-2018-07-31:
  monitor: temporary fix for dead-lock on event recursion

Signed-off-by: Peter Maydell <address@hidden>


Compare: https://github.com/qemu/qemu/compare/42e76456cf68...b89041647422
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