Re: [RFC] [PATCH] [PR gdb/29796] Fix gdbserver delay before quitting in extended-remote

[Kevin Buettner <kevinb@redhat.com>]

On Sat, 14 Oct 2023 02:01:42 +0000
Shivam Saxena <saxens12@mcmaster.ca> wrote:

> Investigating PR29796, where it was noticed that there was a delay when trying to quit the gdb session if connected to gdbserver via stdio. It was also mentioned that using --once​ when launching gdbserver​ would fix this problem and a recommendation was made to always apply --once​ when launching gdbserver​ with stdio​.
> 
> I've explicitly set the run_once​ flag when stdio​ is detected at launch of gdbserver. This does fix the problem as suggested in the bug since the conditional at gdbserver/server.cc:3958​ is always triggered.
> ```
>          if (run_once || (!extended_protocol && !target_running ()))
>             throw_quit ("Quit");
> ```
> However, would it be better to create a new flag for this to facilitate quitting despite
> extended_protocol​ instead of piggybacking on --once​ logic?

I don't see a problem with using 'run_once' for this purpose.  But if there's
something I'm missing, please explain...

> 
> Tested on x86_64 Ubuntu 22.04 natively
> Testsuite had no regressions.
> 
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29796
> ---
> ```
> diff --git a/gdbserver/server.cc b/gdbserver/server.cc
> index e02cdb83b51..3c9e8bc3720 100644
> --- a/gdbserver/server.cc
> +++ b/gdbserver/server.cc
> @@ -3760,6 +3760,8 @@ captured_main (int argc, char *argv[])
>           /* "-" specifies a stdio connection and is a form of port
>              specification.  */
>           port = STDIO_CONNECTION_NAME;
> +        /* auto-imply --once if invoked via stdio. */

Comments are supposed to be sentence-like.  So the first word is
capitalized and it should end with a period (which it does here)
followed by two spaces.  (So... capitalize "auto" and add an extra
space after the period.)

Aside from this nit, your patch looks good to me.

> +        run_once = true;
>           next_arg++;
>           break;
>         }
> ```
> ---
>