Re: [PATCH] gdbserver/linux-low: carry over stop_expected flag after exec (avoid spurious SIGSTOPs)

[Pedro Alves <pedro@palves.net>]

On 2026-06-26 19:00, Simon Marchi wrote:
> On 2026-06-26 13:35, Pedro Alves wrote:
>>> +      unsigned long execing_tid = event_ptid.lwp ();
>>> +      if (ptrace (PTRACE_GETEVENTMSG, event_ptid.lwp (), (PTRACE_TYPE_ARG3) 0,
>>> +		  &execing_tid) != 0)
>>> +	execing_tid = event_ptid.lwp ();
>>
>> This gave me pause -- this is setting execing_tid to the event lwp if ptrace fails.
>> But execing_tid is already initialized to the event lwp.  I think it'd be clearer not
>> to initialize it, like:
>>
>>       unsigned long execing_tid;
>>       if (ptrace (PTRACE_GETEVENTMSG, event_ptid.lwp (), (PTRACE_TYPE_ARG3) 0,
>> 		  &execing_tid) != 0)
>> 	execing_tid = event_ptid.lwp ();
> 
> Well, the question then is: what if the ptrace call fails?  It probably
> never fails, but we still have to think about it.  execing_tid would be
> used uninitialized.  I see three options:

I'm confused with the question.  In the snippet I proposed, if ptrace fails,
then we set execing_tid:

      unsigned long execing_tid;
      if (ptrace (PTRACE_GETEVENTMSG, event_ptid.lwp (), (PTRACE_TYPE_ARG3) 0,
		  &execing_tid) != 0)
	execing_tid = event_ptid.lwp ();  <<< ptrace failed.

So this behaves exactly like your original code, just without the redundant
initialization.

Am I missing something?