[Bug dap/30680] New: [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[Bug dap/30680] New: [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

            Bug ID: 30680
           Summary: [gdb/dap] ThreadSanitizer: data race
                    gdbsupport/event-pipe.h:44 in event_pipe::is_open()
                    const
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: dap
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

Created attachment 15010
  --> https://sourceware.org/bugzilla/attachment.cgi?id=15010&action=edit
gdb.log

When doing a gdb build with gcc 13.1.1 and with -O2 -fno-hoist-adjacent-loads
to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110799, I run into:
...
WARNING: ThreadSanitizer: data race (pid=22165)
Read of size 4 at 0x00000261ca40 by thread T13:
#0 event_pipe::is_open() const
/data/vries/gdb/src/gdb/../gdbsupport/event-pipe.h:44 (gdb+0x92f381) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
  ...
Previous write of size 4 at 0x00000261ca40 by main thread:
#0 event_pipe::close_pipe() /data/vries/gdb/src/gdbsupport/event-pipe.cc:62
(gdb+0x1610e2d) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
...

event-pipe.h:44
...
    bool is_open () const
44  { return m_fds[0] != -1; } 
...

event-pipe.cc:62:
...
    void
    event_pipe::close_pipe ()
    {
      ::close (m_fds[0]);
      ::close (m_fds[1]);
62    m_fds[0] = -1;
      m_fds[1] = -1;
    }
...

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
A bit more elaborate.

WARNING: ThreadSanitizer: data race (pid=22165)
  Read of size 4 at 0x00000261ca40 by thread T13:
    #0 event_pipe::is_open() const
/data/vries/gdb/src/gdb/../gdbsupport/event-pipe.h:44 (gdb+0x92f381) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #1 inf_ptrace_target::async_file_mark_if_open()
/data/vries/gdb/src/gdb/inf-ptrace.h:73 (gdb+0x92f381)
    #2 sigchld_handler /data/vries/gdb/src/gdb/linux-nat.c:4238 (gdb+0x92f381)
    #3 <null> <null> (libtsan.so.2+0x3e2cc) (BuildId:
8f2a9be581a0fcb3d7109755a6067408093b9dbd)
    #4 _Py_read <null> (libpython3.11.so.1.0+0x2590e9) (BuildId:
e08746d8f4494e69c6a275f48c30104fb13e6d81)

  Previous write of size 4 at 0x00000261ca40 by main thread:
    #0 event_pipe::close_pipe() /data/vries/gdb/src/gdbsupport/event-pipe.cc:62
(gdb+0x1610e2d) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #1 inf_ptrace_target::async_file_close()
/data/vries/gdb/src/gdb/inf-ptrace.h:82 (gdb+0x93033c) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #2 linux_nat_target::async(bool) /data/vries/gdb/src/gdb/linux-nat.c:4279
(gdb+0x93033c)
    #3 target_ops::async(bool) /data/vries/gdb/src/gdb/target-delegates.c:2161
(gdb+0xce9b04) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #4 target_async(bool) /data/vries/gdb/src/gdb/target.c:4338 (gdb+0xcf987d)
(BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #5 inferior_event_handler(inferior_event_type)
/data/vries/gdb/src/gdb/inf-loop.c:52 (gdb+0x8b761a) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #6 fetch_inferior_event() /data/vries/gdb/src/gdb/infrun.c:4501
(gdb+0x8f564e) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #7 inferior_event_handler(inferior_event_type)
/data/vries/gdb/src/gdb/inf-loop.c:42 (gdb+0x8b758c) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #8 infrun_async_inferior_event_handler
/data/vries/gdb/src/gdb/infrun.c:9820 (gdb+0x8d4fc7) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #9 check_async_event_handlers() /data/vries/gdb/src/gdb/async-event.c:338
(gdb+0x5a640f) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #10 gdb_do_one_event(int) /data/vries/gdb/src/gdbsupport/event-loop.cc:221
(gdb+0x1600024) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #11 wait_sync_command_done() /data/vries/gdb/src/gdb/top.c:426
(gdb+0xd1874b) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #12 maybe_wait_sync_command_done(int) /data/vries/gdb/src/gdb/top.c:443
(gdb+0xd1cb4c) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #13 execute_command(char const*, int) /data/vries/gdb/src/gdb/top.c:576
(gdb+0xd1cb4c)
    #14 execute_control_command_1 /data/vries/gdb/src/gdb/cli/cli-script.c:529
(gdb+0x675883) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #15 execute_control_command(command_line*, int)
/data/vries/gdb/src/gdb/cli/cli-script.c:701 (gdb+0x675d0e) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #16 execute_control_commands(command_line*, int)
/data/vries/gdb/src/gdb/cli/cli-script.c:411 (gdb+0x675e59) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #17 operator() /data/vries/gdb/src/gdb/cli/cli-script.c:432 (gdb+0x675ef7)
(BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #18 __invoke_impl<void, execute_control_commands_to_string(command_line*,
int)::<lambda()>&> /usr/include/c++/13/bits/invoke.h:61 (gdb+0x675ef7)
    #19 __invoke_r<void, execute_control_commands_to_string(command_line*,
int)::<lambda()>&> /usr/include/c++/13/bits/invoke.h:111 (gdb+0x675ef7)
WROTE: <<<{"type": "event", "event": "output", "body": {"category": "stdout",
"output": "    #20 _M_invoke /usr/include/c++/13/bits/std_function.h:290
(gdb+0x675ef7)
    #21 std::function<void ()>::operator()() const
/usr/include/c++/13/bits/std_function.h:591 (gdb+0xd189c1) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #22 execute_fn_to_ui_file(ui_file*, std::function<void ()>)
/data/vries/gdb/src/gdb/top.c:630 (gdb+0xd189c1)
    #23 execute_fn_to_string(std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >&, std::function<void ()>, bool)
/data/vries/gdb/src/gdb/top.c:644 (gdb+0xd18bab) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #24 execute_control_commands_to_string[abi:cxx11](command_line*, int)
/data/vries/gdb/src/gdb/cli/cli-script.c:430 (gdb+0x672034) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #25 execute_gdb_command /data/vries/gdb/src/gdb/python/python.c:690
(gdb+0xb1176e) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #26 <null> <null> (libpython3.11.so.1.0+0x1cd27c) (BuildId:
e08746d8f4494e69c6a275f48c30104fb13e6d81)
    #27 std::function<void ()>::operator()() const
/usr/include/c++/13/bits/std_function.h:591 (gdb+0xbc8db2) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #28 run_events /data/vries/gdb/src/gdb/run-on-main-thread.c:76
(gdb+0xbc8db2)
    #29 handle_file_event /data/vries/gdb/src/gdbsupport/event-loop.cc:573
(gdb+0x15fe861) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #30 gdb_wait_for_event /data/vries/gdb/src/gdbsupport/event-loop.cc:694
(gdb+0x15feead) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #31 gdb_do_one_event(int) /data/vries/gdb/src/gdbsupport/event-loop.cc:264
(gdb+0x15fff9a) (BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #32 start_event_loop /data/vries/gdb/src/gdb/main.c:412 (gdb+0x98ea81)
(BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #33 captured_command_loop /data/vries/gdb/src/gdb/main.c:476 (gdb+0x98ea81)
    #34 captured_main /data/vries/gdb/src/gdb/main.c:1320 (gdb+0x992784)
(BuildId: c3b5cbc2b30d2ab9521ca0586222e0001ad66898)
    #35 gdb_main(captured_main_args*) /data/vries/gdb/src/gdb/main.c:1339
(gdb+0x992784)
    #36 main /data/vries/gdb/src/gdb/gdb.c:32 (gdb+0x47ab01) (BuildId:
c3b5cbc2b30d2ab9521ca0586222e0001ad66898)

  Location is global 'inf_ptrace_target::m_event_pipe' of size 8 at
0x00000261ca40 (gdb+0x261ca40)

SUMMARY: ThreadSanitizer: data race
/data/vries/gdb/src/gdb/../gdbsupport/event-pipe.h:44 in event_pipe::is_open()
const"

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
Doesn't reproduce all the time.

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
Also reproduces with -O0, reproduced 4 out of 25 times.

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at sourceware dot org

--- Comment #4 from Tom Tromey <tromey at sourceware dot org> ---
>     #2 sigchld_handler /data/vries/gdb/src/gdb/linux-nat.c:4238 (gdb+0x92f381)

This is odd because all the DAP-related threads should be started
with SIGCHLD blocked.

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #5 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #3)
> Also reproduces with -O0, reproduced 4 out of 25 times.

That was with gdb 13.1.1 on openSUSE Tumbleweed.

Also reproduces on openSUSE Leap 15.4, using gcc 7.5.0, reproduced 7 out of 25
times.

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #6 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom Tromey from comment #4)
> >     #2 sigchld_handler /data/vries/gdb/src/gdb/linux-nat.c:4238 (gdb+0x92f381)
> 
> This is odd because all the DAP-related threads should be started
> with SIGCHLD blocked.

I've written an assert to try to catch this situation without tsan:
...
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index 250a8f43282..d6d0ba0f415 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -69,6 +69,7 @@
 #include "gdbsupport/scope-exit.h"
 #include "gdbsupport/gdb-sigmask.h"
 #include "gdbsupport/common-debug.h"
+#include "run-on-main-thread.h"
 #include <unordered_map>

 /* This comment documents high-level logic of this file.
@@ -4227,6 +4228,7 @@ linux_nat_target::supports_disable_randomization ()
 static void
 sigchld_handler (int signo)
 {
+  gdb_assert (is_main_thread ());
   int old_errno = errno;

   if (debug_linux_nat)
diff --git a/gdb/run-on-main-thread.c b/gdb/run-on-main-thread.c
index c7d9de0afc8..f9388e33633 100644
--- a/gdb/run-on-main-thread.c
+++ b/gdb/run-on-main-thread.c
@@ -94,12 +94,27 @@ run_on_main_thread (std::function<void ()> &&func)
   serial_event_set (runnable_event);
 }

+#if CXX_STD_THREAD
+static void
+initialize_main_thread_var (void)
+{
+  static bool initialized = false;
+
+  if (initialized)
+    return;
+  initialized = true;
+
+  main_thread = std::this_thread::get_id ();
+}
+#endif
+
 /* See run-on-main-thread.h.  */

 bool
 is_main_thread ()
 {
 #if CXX_STD_THREAD
+  initialize_main_thread_var ();
   return std::this_thread::get_id () == main_thread;
 #else--
   return true;
@@ -111,7 +126,7 @@ void
 _initialize_run_on_main_thread ()
 {
 #if CXX_STD_THREAD
-  main_thread = std::this_thread::get_id ();
+  initialize_main_thread_var ();
 #endif
   runnable_event = make_serial_event ();
   add_file_handler (serial_event_fd (runnable_event), run_events, nullptr,
...
and it does trigger.

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #7 from Tom de Vries <vries at gcc dot gnu.org> ---
Created attachment 15014
  --> https://sourceware.org/bugzilla/attachment.cgi?id=15014&action=edit
LOG.gz

(In reply to Tom de Vries from comment #6)
> and it does trigger.

In a run of 200, 12 times.

There are problems in other test-cases as well:
...
$ grep ERROR:.*sourcing LOG | sort | uniq -c
      3 ERROR: tcl error sourcing
/data/vries/gdb/src/gdb/testsuite/gdb.dap/ada-scopes.exp.
      6 ERROR: tcl error sourcing
/data/vries/gdb/src/gdb/testsuite/gdb.dap/args-env.exp.
     87 ERROR: tcl error sourcing
/data/vries/gdb/src/gdb/testsuite/gdb.dap/basic-dap.exp.
      6 ERROR: tcl error sourcing
/data/vries/gdb/src/gdb/testsuite/gdb.dap/bt-nodebug.exp.
     18 ERROR: tcl error sourcing
/data/vries/gdb/src/gdb/testsuite/gdb.dap/catch-exception.exp.
     60 ERROR: tcl error sourcing
/data/vries/gdb/src/gdb/testsuite/gdb.dap/cond-bp.exp.
     24 ERROR: tcl error sourcing
/data/vries/gdb/src/gdb/testsuite/gdb.dap/hover.exp.
      6 ERROR: tcl error sourcing
/data/vries/gdb/src/gdb/testsuite/gdb.dap/log-message.exp.
     36 ERROR: tcl error sourcing
/data/vries/gdb/src/gdb/testsuite/gdb.dap/modules.exp.
      3 ERROR: tcl error sourcing
/data/vries/gdb/src/gdb/testsuite/gdb.dap/scopes.exp.
     12 ERROR: tcl error sourcing
/data/vries/gdb/src/gdb/testsuite/gdb.dap/stop-at-main.exp.
...

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #8 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #7)
> Created attachment 15014 [details]
> LOG.gz

Also occurring:
...
"type": "event", "event": "output", "body": {"category": "stdout", "output":
"Recursive internal problem.\n"}, "seq": 24}Content-Length: 129^M
^M
{"type": "event", "event": "output", "body": {"category": "stdout", "output":
"\u0000corrupted double-linked list\n"}
...

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #9 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom de Vries from comment #6)
> diff --git a/gdb/run-on-main-thread.c b/gdb/run-on-main-thread.c
> index c7d9de0afc8..f9388e33633 100644
> --- a/gdb/run-on-main-thread.c
> +++ b/gdb/run-on-main-thread.c
> @@ -94,12 +94,27 @@ run_on_main_thread (std::function<void ()> &&func)
>    serial_event_set (runnable_event);
>  }
>  
> +#if CXX_STD_THREAD
> +static void
> +initialize_main_thread_var (void)
> +{
> +  static bool initialized = false;
> +
> +  if (initialized)
> +    return;
> +  initialized = true;
> +
> +  main_thread = std::this_thread::get_id ();
> +}
> +#endif
> +
>  /* See run-on-main-thread.h.  */
>  
>  bool
>  is_main_thread ()
>  {
>  #if CXX_STD_THREAD
> +  initialize_main_thread_var ();
>    return std::this_thread::get_id () == main_thread;
>  #else--
>    return true;
> @@ -111,7 +126,7 @@ void
>  _initialize_run_on_main_thread ()
>  {
>  #if CXX_STD_THREAD
> -  main_thread = std::this_thread::get_id ();
> +  initialize_main_thread_var ();
>  #endif
>    runnable_event = make_serial_event ();
>    add_file_handler (serial_event_fd (runnable_event), run_events, nullptr,
> ...

Submitted this bit here (
https://sourceware.org/pipermail/gdb-patches/2023-July/201190.html ).

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #10 from Tom Tromey <tromey at sourceware dot org> ---
I definitely (but intermittently) see the failure with the assert patch
applied.
I'm not much closer to finding the problem, though.
I think the challenge is finding out what bit of code might be
unblocking SIGCHLD on this thread.

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #11 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Tom Tromey from comment #10)
> I definitely (but intermittently) see the failure with the assert patch
> applied.
> I'm not much closer to finding the problem, though.
> I think the challenge is finding out what bit of code might be
> unblocking SIGCHLD on this thread.

I set a breakpoint on pthread_create, and ran a basic dap test.  For the dap
threads, there's a backtrace:
...
#24 0x00007ffff7401b7e in _PyObject_FastCallDict (func=<function at remote
0x7fffec10c1e0>, args=0x0, 
    nargs=<optimized out>, kwargs=0x0) at Objects/abstract.c:2310
#25 0x0000000000a353ea in dap_interp::init (this=0x2bfdac0, top_level=true)
    at /data/vries/gdb/src/gdb/python/py-dap.c:82
#26 0x000000000089ef02 in interp_set (interp=0x2bfdac0, top_level=true) at
/data/vries/gdb/src/gdb/interps.c:140
#27 0x000000000089f197 in set_top_level_interpreter (name=0x286de50
<interpreter_p[abi:cxx11]+16> "dap")
    at /data/vries/gdb/src/gdb/interps.c:209
#28 0x000000000091ac77 in captured_main_1 (context=0x7fffffffdaa0) at
/data/vries/gdb/src/gdb/main.c:1139
...
so I tried to wrap the code around the py-dap.c:82:
...
  gdbpy_ref<> result_obj (PyObject_CallObject (func.get (), nullptr));
  if (result_obj == nullptr)
    gdbpy_handle_exception ();
...
in the gdb::block_signals wrapper, but that didn't fix it either.

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at sourceware dot org   |tromey at sourceware dot org
   Target Milestone|---                         |14.1

--- Comment #12 from Tom Tromey <tromey at sourceware dot org> ---
Found it.

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #13 from Tom Tromey <tromey at sourceware dot org> ---
https://sourceware.org/pipermail/gdb-patches/2023-July/201215.html

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

--- Comment #14 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom Tromey <tromey@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=30c01bb104e4dfc50e8cf3d0312bbf7d22f73d10

commit 30c01bb104e4dfc50e8cf3d0312bbf7d22f73d10
Author: Tom Tromey <tromey@adacore.com>
Date:   Fri Jul 28 12:02:38 2023 -0600

    Restore previous sigmask in gdb.block_signals

    Tom de Vries found a bug where, sometimes, a SIGCHLD would be
    delivered to a non-main thread, wreaking havoc.

    The problem is that gdb.block_signals after first blocking a set of
    signals, then unblocked the same set rather than restoring the initial
    situation.  This function being called from the DAP thread lead to
    SIGCHLD being unblocked there.

    This patch fixes the problem by restoring the previous set of signals
    instead.

    Tested-by: Tom de Vries <tdevries@suse.de>
    Reviewed-By: Tom de Vries <tdevries@suse.de>
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30680

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[Bug dap/30680] [gdb/dap] ThreadSanitizer: data race gdbsupport/event-pipe.h:44 in event_pipe::is_open() const

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30680

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #15 from Tom Tromey <tromey at sourceware dot org> ---
Fixed.

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