Re: [PATCH v3 08/34] Always run async signal handlers in the main UI

Simon Marchi
2016-05-19T19:28:28Z

On 16-05-06 08:34 AM, Pedro Alves wrote:
> Async signal handlers have no connection to whichever was the current
> UI, and thus always run on the main one.
>
> gdb/ChangeLog:
> yyyy-mm-dd Pedro Alves <palves@redhat.com>
>
> * event-loop.c: Include top.h.
> (invoke_async_signal_handlers): Switch to the main UI.
> * event-top.c (main_ui_): Update comment.
> (main_ui): New global.
> * top.h (main_ui): Declare.
> ---
> gdb/event-loop.c | 4 ++++
> gdb/event-top.c | 5 ++---
> gdb/top.h | 5 +++++
> 3 files changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/gdb/event-loop.c b/gdb/event-loop.c
> index 60ef2a5..fe28305 100644
> --- a/gdb/event-loop.c
> +++ b/gdb/event-loop.c
> @@ -35,6 +35,7 @@
> #include "gdb_sys_time.h"
> #include "gdb_select.h"
> #include "observer.h"
> +#include "top.h"
>
> /* Tell create_file_handler what events we are interested in.
> This is used by the select version of the event loop. */
> @@ -967,6 +968,9 @@ invoke_async_signal_handlers (void)
> break;
> any_ready = 1;
> async_handler_ptr->ready = 0;
> + /* Async signal handlers have no connection to whichever was the
> + current UI, and thus always run on the main one. */
> + current_ui = main_ui;
> (*async_handler_ptr->proc) (async_handler_ptr->client_data);
> }
>
> diff --git a/gdb/event-top.c b/gdb/event-top.c
> index c6e3b7e..63f6896 100644
> --- a/gdb/event-top.c
> +++ b/gdb/event-top.c
> @@ -437,11 +437,10 @@ top_level_prompt (void)
> return xstrdup (prompt);
> }
>
> -/* The main UI. This is the UI that is bound to stdin/stdout/stderr.
> - It always exists and is created automatically when GDB starts
> - up. */
> +/* The main UI. */
> static struct ui main_ui_;
>
> +struct ui *main_ui = &main_ui_;

I'd suggest making the pointer const, to show (and make sure) that the main ui
never changes throughout the lifetime of the gdb instance:

+struct ui * const main_ui = &main_ui_;

> struct ui *current_ui = &main_ui_;
> struct ui *ui_list = &main_ui_;

ui_list could be const for the same reason, while we're at it.