[Bug admin/28331] New: Multi-threaded exec pthread_create and dlopen may cause deadlock

[Bug admin/28331] New: Multi-threaded exec pthread_create and dlopen may cause deadlock

[xujing99 at huawei dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28331

            Bug ID: 28331
           Summary: Multi-threaded exec pthread_create and dlopen may
                    cause deadlock
           Product: glibc
           Version: 2.35
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: admin
          Assignee: unassigned at sourceware dot org
          Reporter: xujing99 at huawei dot com
                CC: carlos at redhat dot com
  Target Milestone: ---

after merge commit 1387ad6225c2222f027790e3f460e31aa5dd2c54, multi-threaded
exec pthread_create and dlopen may cause deadlock.

thread1：dlopen hold dl_load_lock and then load a dynamic library which will
hold ACE_lock(defined by my self)
thread2：a program hold ACE_lock and then call
pthread_create=>_dl_allocate_tls_init will hold dlopen dl_load_lock

in this case, it will cause deadlock.

for example:
thread1：dlopen => hold dl_load_lock => spawn_n => wait for hold ACE_lock
thread2：spawn_n => hold ACE_lock => pthread_create => _dl_allocate_tls_init =>
wait for hold dl_load_lock
(spawn_n is my own function)

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[Bug admin/28331] Multi-threaded exec pthread_create and dlopen may cause deadlock

[xujing99 at huawei dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28331

--- Comment #1 from xujing <xujing99 at huawei dot com> ---
If I have a c++ dynamic library(named libA.so) that contains a global object,
the global object will call the post-constructor at initialization and hold
it's own lock(named A_lock) when dlopen loads libA.so. Assume that two threads
execute the following process：
    Thread1:dlopen(libA.so) => hold dl_load_lock => load libA.so => init global 
            object from libA.so => wait for hold A_lock
    Thread2:my own code hold A_lock => pthread_create => _dl_allocate_tls_init 
            => wait for hold dl_load_lock
In this case, an ABBA deadlock occurs. Is this a bug?

My stack looks like this:
Thread 1 (LWP 136013):
#0  0x00007f57a108510d in ?? () from /usr/lib64/libpthread.so.0
#1  0x00007f57a107e4d1 in pthread_mutex_lock () from /usr/lib64/libpthread.so.0
#1  stack waiting for holding A_lock
...
#6  0x00007f5781c1bb8b in LogProcess::Init (strProcName=...,
nProcHandle=nProcHandle@entry=0) at
./service/biz_frame/code/server/src/logging/logprocess.cpp:107
...
#20 0x00007f57a0fef21f in _dl_catch_exception () from /usr/lib64/libc.so.6
#21 0x00007f57a786442b in ?? () from /lib64/ld-linux-x86-64.so.2
#22 0x00007f57a3de2296 in ?? () from /usr/lib64/libdl.so.2
#23 0x00007f57a0fef21f in _dl_catch_exception () from /usr/lib64/libc.so.6
#24 0x00007f57a0fef2af in _dl_catch_error () from /usr/lib64/libc.so.6
#25 0x00007f57a3de2985 in ?? () from /usr/lib64/libdl.so.2
#26 0x00007f57a3de2351 in dlopen () from /usr/lib64/libdl.so.2
...
...
#38 0x00007f57a0fb3520 in clone () from /usr/lib64/libc.so.6

Thread 2 (LWP 134627):
#0  0x00007f57a108510d in ?? () from /usr/lib64/libpthread.so.0
#1  0x00007f57a107e580 in pthread_mutex_lock () from /usr/lib64/libpthread.so.0
#2  0x00007f57a7863835 in _dl_allocate_tls_init () from
/lib64/ld-linux-x86-64.so.2
#3  0x00007f57a107cb7c in pthread_create () from /usr/lib64/libpthread.so.0
...
#10 Stack holding A_lock
...
#14 0x0000561689e0d579 in main ()

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[Bug dynamic-link/28331] Multi-threaded exec pthread_create and dlopen may cause deadlock

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28331

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|admin                       |dynamic-link

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