RE: [PATCH v7 5/5] gdb/infrun: handle already-exited threads when attempting to stop

["Aktemur, Tankut Baris" <tankut.baris.aktemur@intel.com>]

On Wednesday, April 22, 2020 5:01 PM, Aktemur, Tankut Baris wrote:
> diff --git a/gdb/infrun.c b/gdb/infrun.c
> index 167d50ff3ab..93169269553 100644
> --- a/gdb/infrun.c
> +++ b/gdb/infrun.c
> @@ -4781,7 +4781,47 @@ stop_all_threads (void)
>  	{
>  	  int need_wait = 0;
> 
> -	  update_thread_list ();
> +	  for (inferior *inf : all_non_exited_inferiors ())
> +	    {

Sorry.  There is a 'switch_to_inferior_no_thread (inf);', here.

> +	      update_thread_list ();
> +
> +	      /* After updating the thread list, it's possible to end
> +		 up with pid != 0 but no threads, if the inf's process
> +		 has exited but we have not processed that event yet.
> +		 The exit event must be waiting somewhere in the queue
> +		 to be processed.  Silently add a thread so that we do
> +		 a wait_one() below to pick the pending event.  */
> +
> +	      bool has_threads = false;
> +	      for (thread_info *tp ATTRIBUTE_UNUSED
> +		     : inf->non_exited_threads ())
> +		{
> +		  has_threads = true;
> +		  break;
> +		}
> +
> +	      if (has_threads)
> +		continue;
> +
> +	      ptid_t ptid (inf->pid, inf->pid, 0);
> +
> +	      /* Re-surrect the thread, if not physically deleted.
> +		 Add a new one otherwise.  */
> +	      thread_info *t = find_thread_ptid (inf->process_target (), ptid);
> +	      gdb_assert (t == nullptr || t->state == THREAD_EXITED);
> +
> +	      if (debug_infrun)
> +		fprintf_unfiltered (gdb_stdlog, "infrun: stop_all_threads,"
> +				    " inf (pid %d): %s a thread", inf->pid,
> +				    (t == nullptr)
> +				    ? "adding" : "resurrecting");
> +
> +	      if (t == nullptr)
> +		t = add_thread_silent (inf->process_target (), ptid);
> +
> +	      set_executing (inf->process_target (), ptid, true);
> +	      t->state = THREAD_STOPPED;
> +	    }

Thanks.
-Baris


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