<p>Sorry, I overlooked gdb:<br>
(gdb) bt<br>
#0  syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38<br>
<a href="https://github.com/kamailio/kamailio/issues/1" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/1" data-id="31891578" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#1</a>  0x00007f600269d47c in futex_get (lock=0x7f5ffe91d748) at ../cfgt/../../parser/../mem/../futexlock.h:121<br>
<a href="https://github.com/kamailio/kamailio/pull/2" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/2" data-id="41491271" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#2</a>  0x00007f60026a6190 in dbg_get_mod_debug_level (mname=0x797349 "core", mnlen=4, mlevel=0x7ffc8bb3a9fc) at debugger_api.c:1479<br>
<a href="https://github.com/kamailio/kamailio/pull/3" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/3" data-id="48744343" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#3</a>  0x00000000004752c5 in get_debug_level (mname=0x797349 "core", mnlen=4) at dprint.c:164<br>
<a href="https://github.com/kamailio/kamailio/pull/4" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/4" data-id="49856885" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#4</a>  0x000000000063fc06 in fm_malloc (qmp=0x7f5ffe699000, size=37, file=0x7f60026b9b34 "debugger: debugger_api.c", func=0x7f60026bae40 <<strong>FUNCTION</strong>.8648> "dbg_set_mod_debug_level", line=1352, <br>
    mname=0x7f60026b8d3e "debugger") at mem/f_malloc.c:438<br>
<a href="https://github.com/kamailio/kamailio/issues/5" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/5" data-id="51480460" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#5</a>  0x000000000064633c in fm_shm_malloc (qmp=0x7f5ffe699000, size=37, file=0x7f60026b9b34 "debugger: debugger_api.c", func=0x7f60026bae40 <<strong>FUNCTION</strong>.8648> "dbg_set_mod_debug_level", line=1352, <br>
    mname=0x7f60026b8d3e "debugger") at mem/f_malloc.c:1088<br>
<a href="https://github.com/kamailio/kamailio/issues/6" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/6" data-id="51489870" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#6</a>  0x00007f60026a565a in dbg_set_mod_debug_level (mname=0x2aa07e0 "core", mnlen=4, mlevel=0x7ffc8bb3abfc) at debugger_api.c:1352<br>
<a href="https://github.com/kamailio/kamailio/issues/7" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/7" data-id="51492477" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#7</a>  0x00007f60026a3806 in dbg_rpc_set_mod_level (rpc=0x7f6003616660 , ctx=0x7ffc8bb3acd0) at debugger_api.c:999<br>
<a href="https://github.com/kamailio/kamailio/issues/8" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/8" data-id="51499233" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#8</a>  0x00007f60033d2e77 in process_rpc_req (buf=0x2aa07c4 "\241\003\034\023\212\243\062\221\022dbg.set_mod_level", size=35, bytes_needed=0x7ffc8bb3ade8, sh=0x7ffc8bb3ae10, saved_state=0x2ab07c8)<br>
    at binrpc_run.c:675<br>
<a href="https://github.com/kamailio/kamailio/issues/9" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/9" data-id="51703057" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#9</a>  0x00007f6003404253 in handle_stream_read (s_c=0x2aa0790, idx=-1) at io_listener.c:511<br>
<a href="https://github.com/kamailio/kamailio/pull/10" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/10" data-id="52436308" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#10</a> 0x00007f6003405c8a in handle_io (fm=0x7f6006d84498, events=1, idx=-1) at io_listener.c:706<br>
<a href="https://github.com/kamailio/kamailio/issues/11" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/11" data-id="52569646" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#11</a> 0x00007f60033fd4df in io_wait_loop_epoll (h=0x7f6003617420 , t=10, repeat=0) at ../../io_wait.h:1061<br>
<a href="https://github.com/kamailio/kamailio/pull/12" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/12" data-id="52744476" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#12</a> 0x00007f60034013c3 in io_listen_loop (fd_no=1, cs_lst=0x2a9e400) at io_listener.c:281<br>
<a href="https://github.com/kamailio/kamailio/pull/13" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/13" data-id="52784350" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#13</a> 0x00007f60033db58c in mod_child (rank=0) at ctl.c:320<br>
<a href="https://github.com/kamailio/kamailio/pull/14" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/14" data-id="52819753" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#14</a> 0x00000000005ae1cb in init_mod_child (m=0x7f6006d25060, rank=0) at sr_module.c:915<br>
<a href="https://github.com/kamailio/kamailio/issues/15" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/15" data-id="52852064" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#15</a> 0x00000000005adee8 in init_mod_child (m=0x7f6006d25660, rank=0) at sr_module.c:912<br>
<a href="https://github.com/kamailio/kamailio/pull/16" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/16" data-id="53297477" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#16</a> 0x00000000005adee8 in init_mod_child (m=0x7f6006d26d78, rank=0) at sr_module.c:912<br>
<a href="https://github.com/kamailio/kamailio/pull/17" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/17" data-id="53387906" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#17</a> 0x00000000005adee8 in init_mod_child (m=0x7f6006d272b8, rank=0) at sr_module.c:912<br>
<a href="https://github.com/kamailio/kamailio/pull/18" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/18" data-id="53397137" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#18</a> 0x00000000005adee8 in init_mod_child (m=0x7f6006d276e8, rank=0) at sr_module.c:912<br>
<a href="https://github.com/kamailio/kamailio/pull/19" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/19" data-id="53511603" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#19</a> 0x00000000005adee8 in init_mod_child (m=0x7f6006d28328, rank=0) at sr_module.c:912<br>
<a href="https://github.com/kamailio/kamailio/pull/20" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/20" data-id="53562369" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#20</a> 0x00000000005ae503 in init_child (rank=0) at sr_module.c:941<br>
<a href="https://github.com/kamailio/kamailio/issues/21" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/21" data-id="53562546" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#21</a> 0x00000000004b34c1 in main_loop () at main.c:1671<br>
<a href="https://github.com/kamailio/kamailio/pull/22" class="issue-link js-issue-link" data-url="https://github.com/kamailio/kamailio/issues/22" data-id="53569003" data-error-text="Failed to load issue title" data-permission-text="Issue title is private">#22</a> 0x00000000004b9c4c in main (argc=4, argv=0x7ffc8bb3b9a8) at main.c:2597</p>

<p>The deadlock makes sense. MDBG() in fm_malloc() issues dbg_get_mod_debug_level() which gets the same lock that dbg_set_mod_debug_level() already got.</p>

<p>The first option would be to never use locks for dbg_get_mod_debug_level()(because the list is just iterated through, no list mutations).<br>
The other option is to create different get/set locks for level/facility in <code>struct _dbg_mod_slot</code>.</p>

<p>What do you think is the best option?</p>

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