Re: [PATCH 15/21] fbcon: Consistently protect deferred_takeover with console_lock()

Sam Ravnborg
2022-02-05T23:02:01Z

On Mon, Jan 31, 2022 at 10:05:46PM +0100, Daniel Vetter wrote:
> This shouldn't be a problem in practice since until we've actually
> taken over the console there's nothing we've registered with the
> console/vt subsystem, so the exit/unbind path that check this can't
> do the wrong thing. But it's confusing, so fix it by moving it a tad
> later.
>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Du Cheng <ducheng2@gmail.com>
> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Cc: Claudio Suarez <cssk@net-c.es>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>

It had helped me if the commitlog was explicit that the
deferred_takeover falg is moved to the worker function to reset it as
late as possible.

With the commit log updated:
Acked-by: Sam Ravnborg <sam@ravnborg.org>

> ---
> drivers/video/fbdev/core/fbcon.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index 496bc5f2133e..11b9f962af6f 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -3247,6 +3247,9 @@ static void fbcon_register_existing_fbs(struct work_struct *work)
>
> console_lock();
>
> + deferred_takeover = false;
> + logo_shown = FBCON_LOGO_DONTSHOW;
> +
> for_each_registered_fb(i)
> fbcon_fb_registered(registered_fb[i]);
>
> @@ -3264,8 +3267,6 @@ static int fbcon_output_notifier(struct notifier_block *nb,
> pr_info("fbcon: Taking over console\n");
>
> dummycon_unregister_output_notifier(&fbcon_output_nb);
> - deferred_takeover = false;
> - logo_shown = FBCON_LOGO_DONTSHOW;
>
> /* We may get called in atomic context */
> schedule_work(&fbcon_deferred_takeover_work);
> --
> 2.33.0