[Bug gdb/17247] gdb freezes on multi threaded app (test-case attached)

["corinna at vinschen dot de" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=17247

--- Comment #38 from Corinna Vinschen <corinna at vinschen dot de> ---
(In reply to Evgeny Grablyk from comment #35)
> I've tested GDB with Doug Evans' patch and it seems to be working for me --
> I've tested it on a couple Qt apps so far. Patch with corrections proposed
> by Pedro Alves also works.
> 
> Could it be possible that the Cygwin hang is caused by something else? When
> this bug manifests itself on my system, GUI apps never display at all, let
> alone run for a second, and killing the hung app leaves GDB operable.

I honestly don't know.  This was the first release of GDB for Cygwin built
with Python support so I suspected this.  However, even after rebuilding
GDB without python support, GDB and the inferior still hang the same way.
For completeness I also tried Doug's patch, but to no avail.

I also attached a second GDB to the hanging GDB and I got this backtrace:

(gdb) thr 1
[Switching to thread 1 (Thread 2832.0x640)]
#0  0x00007ff9efc6c7da in ntdll!ZwWaitForDebugEvent ()
   from /mnt/c/WINDOWS/SYSTEM32/ntdll.dll
(gdb) bt
#0  0x00007ff9efc6c7da in ntdll!ZwWaitForDebugEvent ()
   from /mnt/c/WINDOWS/SYSTEM32/ntdll.dll
#1  0x00007ff9ed31a0c1 in WaitForDebugEvent ()
   from /mnt/c/WINDOWS/system32/KERNELBASE.dll
#2  0x000000010042b9b6 in get_windows_debug_event (pid=-1, ourstatus=0xc3a2c0,
    ops=0x6000bfb80) at /usr/src/debug/gdb-7.8-1/gdb/windows-nat.c:1409
#3  windows_wait (ops=0x6000bfb80, ptid=..., ourstatus=0xc3a2c0, options=0)
    at /usr/src/debug/gdb-7.8-1/gdb/windows-nat.c:1643
#4  0x000000010055734b in delegate_wait (self=<optimized out>, arg1=...,
    arg2=<optimized out>, arg3=0)
    at /usr/src/debug/gdb-7.8-1/gdb/target-delegates.c:60
#5  0x000000010055f2d4 in target_wait (ptid=..., status=status@entry=0xc3a2c0,
    options=options@entry=0) at /usr/src/debug/gdb-7.8-1/gdb/target.c:2107
#6  0x0000000100524efc in wait_for_inferior ()
    at /usr/src/debug/gdb-7.8-1/gdb/infrun.c:2828
#7  0x000000010052517a in proceed (addr=<optimized out>,
    siggnal=siggnal@entry=GDB_SIGNAL_0, step=step@entry=0)
    at /usr/src/debug/gdb-7.8-1/gdb/infrun.c:2388
#8  0x0000000100517fbd in run_command_1 (args=0x0, from_tty=1,
    tbreak_at_main=<optimized out>)
    at /usr/src/debug/gdb-7.8-1/gdb/infcmd.c:630
#9  0x00000001005f789d in execute_command (p=<optimized out>,
    p@entry=0x600038940 "", from_tty=1)
    at /usr/src/debug/gdb-7.8-1/gdb/top.c:462
#10 0x000000010053c206 in command_handler (command=0x600038940 "")
    at /usr/src/debug/gdb-7.8-1/gdb/event-top.c:433
#11 0x000000010053c838 in command_line_handler (rl=<optimized out>)
    at /usr/src/debug/gdb-7.8-1/gdb/event-top.c:630
#12 0x00000003f5285c03 in rl_callback_read_char ()
   from /usr/bin/cygreadline7.dll
#13 0x000000010053c269 in rl_callback_read_char_wrapper (
    client_data=<optimized out>)
    at /usr/src/debug/gdb-7.8-1/gdb/event-top.c:167
#14 0x000000010053ae54 in process_event ()
    at /usr/src/debug/gdb-7.8-1/gdb/event-loop.c:343
#15 0x000000010053b1d7 in gdb_do_one_event ()
    at /usr/src/debug/gdb-7.8-1/gdb/event-loop.c:407
#16 0x000000010053b41e in start_event_loop ()
    at /usr/src/debug/gdb-7.8-1/gdb/event-loop.c:432
#17 0x0000000100534b56 in captured_command_loop (data=data@entry=0x0)
    at /usr/src/debug/gdb-7.8-1/gdb/main.c:302
#18 0x0000000100531c8a in catch_errors (
    func=func@entry=0x100534b40 <captured_command_loop>,
    func_args=func_args@entry=0x0,
    errstring=errstring@entry=0x1007621c3 <__PRETTY_FUNCTION__.13666+257> "",
    mask=mask@entry=RETURN_MASK_ALL)
    at /usr/src/debug/gdb-7.8-1/gdb/exceptions.c:506
#19 0x0000000100535b5b in captured_main (data=data@entry=0xc3aab0)
    at /usr/src/debug/gdb-7.8-1/gdb/main.c:1155
#20 0x0000000100531c8a in catch_errors (
    func=func@entry=0x1005350b0 <captured_main>,
    func_args=func_args@entry=0xc3aab0,
    errstring=errstring@entry=0x1007621c3 <__PRETTY_FUNCTION__.13666+257> "",
    mask=mask@entry=RETURN_MASK_ALL)
    at /usr/src/debug/gdb-7.8-1/gdb/exceptions.c:506
#21 0x0000000100536090 in gdb_main (args=args@entry=0xc3aab0)
    at /usr/src/debug/gdb-7.8-1/gdb/main.c:1163
#22 0x00000001006e8e58 in main (argc=2, argv=0xc3ab30)
    at /usr/src/debug/gdb-7.8-1/gdb/gdb.c:33



Corinna

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