Re: MI and SIGINT

[Andrew Burgess <andrew.burgess@embecosm.com>]

* Hafiz Abid Qadeer <abid_qadeer@mentor.com> [2020-07-14 12:03:11 +0100]:

> Hi All,
> We have observed that a SIGINT send by an IDE can cause GDB to not print
> MI stopped messages. Although this is very difficult to reproduce by
> hand but the sequence look something like this.
> 
> 1. You do continue and GDB hits a breakpoint and starts calling the
> observers.
> 2. One of the observer will call into python sniffers.
> 3. If during that time, a SIGINT has arrived, it will cause python to
> throw exception which will cause GDB to abandon printing the stopped
> message.

I don't have time to test this right now, but if your diagnosis is
correct then this should be easy to test.  Write a sniffer that sends
itself a SIGINT and check you see the problem.

This should make it possible to create a reliable test case.

Thanks,
Andrew


> 
> It is not a big problem in cli mode but can leave IDE in bit of limbo. I
> was wondering if this is intended behavior with the SIGINT and MI.
> 
> The call stack of the exception looks like this:
> 
> #3  0x0000555555857ff1 in throw_quit
> #4  0x00005555559b9bdb in gdbpy_print_stack_or_quit
> #5  0x00005555559aa57f in pyuw_sniffer
> #6  0x0000555555838a23 in frame_unwind_try_unwinder
> #7  0x0000555555838b90 in frame_unwind_find_by_frame
> #8  0x000055555583e7ad in get_frame_type
> #9  0x0000555555a445e7 in print_frame_info
>    #10 0x0000555555a42a9f in print_stack_frame
> #11 0x00005555558b4ebe in print_stop_location
> #12 0x00005555558b4f4b in print_stop_event
> #13 0x000055555591ab17 in mi_on_normal_stop_1
> #14 0x000055555591ad34 in mi_on_normal_stop
> #15 0x0000555555618517 in std::_Function_handler<void (bpstats*, int),
> void (*)(bpstats*, int)>::_M_invoke(std::_Any_data const&, bpstats*&&,
> int&&)
> #16 0x00005555558b9d82 in std::function<void (bpstats*,
> int)>::operator()(bpstats*, int) const
> #17 0x00005555558b93db in gdb::observers::observable<bpstats*, int>::notify
> #18 0x00005555558b5832 in normal_stop
> 
> Regards,
> -- 
> Hafiz Abid Qadeer
> Mentor Embedded/CodeSourcery