[asterisk-dev] [Code Review] Deadlock x2 Race on pickup and a race on hint remove

[irroot]

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This is an automatically generated e-mail. To reply, visit:
https://reviewboard.asterisk.org/r/1166/
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Review request for Asterisk Developers.


Summary
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Can some one give me a good reason why the bellow order should not be reversed ??

ao2_callback runs on various threads holding container locks we must make sure we
lock the element before locking a container i have a feeling asterisk could be riddled
with these deadlocks / race conditions ....

/* disclaimer the first lock output is from a patched app_directed_pickup 
 *
 * the changes use a callback the same as features.c
 *
 */


=======================================================================
=== Currently Held Locks ==============================================
=======================================================================
===
=== <pending> <lock#> (<file>): <lock type> <line num> <function> <lock name> <lock addr> (times locked)
===
=== Thread ID: 0xab37bb70 (pbx_thread           started at [ 5038] pbx.c ast_pbx_start())
=== ---> Lock #0 (channel.c): MUTEX 6241 ast_do_masquerade channels 0x89de1d0 (1)
=== ---> Waiting for Lock #1 (channel.c): MUTEX 6244 ast_do_masquerade original 0x92fa3a8 (1)
=== --- ---> Locked Here: app_directed_pickup.c line 322 (pickup_by_group)
=== -------------------------------------------------------------------
===
=== Thread ID: 0xab597b70 (pbx_thread           started at [ 5038] pbx.c ast_pbx_start())
=== ---> Waiting for Lock #0 (app_directed_pickup.c): MUTEX 155 pickup_do target 0x92fa3a8 (1)
=== --- ---> Locked Here: app_directed_pickup.c line 322 (pickup_by_group)
=== -------------------------------------------------------------------
===
=== Thread ID: 0xab04bb70 (pbx_thread           started at [ 5038] pbx.c ast_pbx_start())
=== ---> Lock #0 (app_directed_pickup.c): MUTEX 322 pickup_by_group target 0x92fa3a8 (1)
=== ---> Lock #1 (cdr.c): RDLOCK 1142 post_cdr &(&be_list)->lock 0x81f1cc8 (1)
=== ---> Waiting for Lock #2 (astobj2.c): MUTEX 657 internal_ao2_callback c 0x89de1d0 (1)
=== --- ---> Locked Here: channel.c line 6241 (ast_do_masquerade)
=== -------------------------------------------------------------------
======================================================================= 


=======================================================================
=== Currently Held Locks ==============================================
=======================================================================
===
=== <pending> <lock#> (<file>): <lock type> <line num> <function> <lock name> <lock addr> (times locked)
===
=== Thread ID: 0xb3c41b70 (tps_processing_function started at [  451] taskprocessor.c ast_taskprocessor_get())
=== ---> Lock #0 (pbx.c): MUTEX 4269 handle_statechange hints 0x97a4b48 (1)
=== ---> Waiting for Lock #1 (pbx.c): MUTEX 4270 handle_statechange hint 0xb04cf7c0 (1)
=== --- ---> Locked Here: pbx.c line 4523 (ast_remove_hint)
=== -------------------------------------------------------------------
===
=== Thread ID: 0xb09f6b70 (do_monitor           started at [24621] chan_sip.c restart_monitor())
=== ---> Lock #0 (chan_sip.c): MUTEX 24119 handle_request_do &netlock 0xb309fdc0 (1)
=== ---> Lock #1 (chan_sip.c): MUTEX 7593 find_call p 0xffb8d48 (1)
=== ---> Waiting for Lock #2 (astobj2.c): MUTEX 657 internal_ao2_callback c 0x97a4b48 (1)
=== --- ---> Locked Here: pbx.c line 4269 (handle_statechange)
=== -------------------------------------------------------------------
===
=== Thread ID: 0xb05c3b70 (netconsole           started at [ 1344] asterisk.c listener())
=== ---> Lock #0 (loader.c): MUTEX 673 ast_module_reload &reloadlock 0x81f5280 (1)
=== ---> Lock #1 (loader.c): MUTEX 711 ast_module_reload &(&module_list)->lock 0x81f5208 (1)
=== ---> Lock #2 (pbx.c): MUTEX 4523 ast_remove_hint hint 0xb04cf7c0 (1)
=== ---> Waiting for Lock #3 (astobj2.c): MUTEX 657 internal_ao2_callback c 0x97a4b48 (1)
=== --- ---> Locked Here: pbx.c line 4269 (handle_statechange)
=== -------------------------------------------------------------------
===
=======================================================================


This addresses bugs 18654 and 19091.
    https://issues.asterisk.org/view.php?id=18654
    https://issues.asterisk.org/view.php?id=19091


Diffs
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  /branches/1.8/main/channel.c 313184 
  /branches/1.8/main/pbx.c 313184 

Diff: https://reviewboard.asterisk.org/r/1166/diff


Testing
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Thanks,

irroot

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