linux-kernel - Re: [RFC 1/1] tty: vt.c: Fix TIOCL_BLANKSCREEN VT console blanking if blankinterval == 0

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Message-ID: <20190226112026.GA21300@localhost.localdomain>
Date:   Tue, 26 Feb 2019 19:20:26 +0800
From:   Tom Li <tomli@...li.me>
To:     Nicolas Pitre <nicolas.pitre@...aro.org>,
        linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Adam Borowski <kilobyte@...band.pl>,
        Mikulas Patocka <mpatocka@...hat.com>,
        Alexander Potapenko <glider@...gle.com>,
        Yifeng Li <tomli@...li.me>,
        Mike Frysinger <vapier@...omium.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>
Subject: Re: [RFC 1/1] tty: vt.c: Fix TIOCL_BLANKSCREEN VT console blanking
 if blankinterval == 0

> Wouldn't this problem be fixed simply by the following:
> 
> diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
> index 9646ff63e7..41b17c4b5a 100644
> --- a/drivers/tty/vt/vt.c
> +++ b/drivers/tty/vt/vt.c
> @@ -4151,8 +4151,6 @@ void do_blank_screen(int entering_gfx)
>  		return;
>  	}
>  
> -	if (blank_state != blank_normal_wait)
> -		return;
>  	blank_state = blank_off;
>  
>  	/* don't blank graphics */
> 
> I just can't find a logical reason for that conditional return.
> 
> 
> Nicolas

I see. I was concerned about the possibly unwanted effect if the function
is reentered, but it seems that there's no logic reason to worry at all.

I'll send a new patch according to your suggestion.

Thanks,
Tom Li