Re: Inadvertently run inferior threads

[Eli Zaretskii <eliz at gnu dot org>]

Ping!  With the GDB 7.10 branching date looming, could we please
decide ASAP if the patch I proposed for this annoying problem is good
to go in?

TIA.

> Date: Thu, 11 Jun 2015 16:26:10 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: gdb-patches@sourceware.org
> 
> [I'm taking this to gdb-patches@, as I'm suggesting a patch.]
> 
> > Date: Wed, 10 Jun 2015 18:50:13 +0300
> > From: Eli Zaretskii <eliz@gnu.org>
> > Cc: gdb@sourceware.org
> > 
> > So 'set_running' is called, and it is called with minus_one_ptid,
> > which then has the effect of marking all the threads as running.
> > 
> > What I don't understand is why doesn't the breakpoint we set at exit
> > from the inferior function countermand that.  I do see the effect of
> > that breakpoint if I turn on infrun debugging:
> > 
> >   infrun: target_wait (-1, status) =
> >   infrun:   4608 [Thread 4608.0x4900],
> >   infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
> >   infrun: TARGET_WAITKIND_STOPPED
> >   infrun: stop_pc = 0x88ba9f
> >   infrun: BPSTAT_WHAT_STOP_SILENT
> >   infrun: stop_waiting
> > 
> > Why don't we mark all threads as stopped when we hit the breakpoint?
> > is that because of #3 above?
> 
> Answering myself: yes.
> 
> > Any ideas how to solve this annoying problem?
> 
> One idea is implemented in the patch below.  I tested it in a
> MinGW-compiled GDB doing native debugging, and it completely solved
> the problem for me: I see additional threads started during an
> infcall, but none of those dreaded "the selected thread is running"
> error messages.
> 
> OK to commit (with a suitable ChangeLog entry)?
> 
> --- gdb/infrun.c~0	2015-01-13 15:14:47 +0200
> +++ gdb/infrun.c	2015-06-11 07:13:54 +0300
> @@ -6508,8 +6508,14 @@ normal_stop (void)
>       running, all without informing the user/frontend about state
>       transition changes.  If this is actually a call command, then the
>       thread was originally already stopped, so there's no state to
> -     finish either.  */
> -  if (target_has_execution && inferior_thread ()->control.in_infcall)
> +     finish either.  Howevever, if target doesn't support asynchronous
> +     execution, we must mark all of its threads as stopped, because
> +     that's what such targets do when the thread running in an infcall
> +     stops.  (The cleanup will call finish_thread_state with
> +     minus_one_ptid in that case.)  */
> +  if (target_has_execution
> +      && inferior_thread ()->control.in_infcall
> +      && target_can_async_p ())
>      discard_cleanups (old_chain);
>    else
>      do_cleanups (old_chain);
>